Speed of sound: Wikis

  
  
  

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Sound measurements
Sound pressure p
Sound pressure level (SPL)
Particle velocity v
Particle velocity level (SVL)
   (Sound velocity level)
Particle displacement ξ
Sound intensity I
Sound intensity level (SIL)
Sound power Pac
Sound power level (SWL)
Sound energy density E
Sound energy flux q
Surface S
Acoustic impedance Z
Speed of sound c
.The speed of sound is the rate of travel of a sound wave through an elastic medium.^ Sound can travel through any medium, but it cannot travel through a vacuum.
  • The Nature of Sound - The Physics Hypertextbook 14 January 2010 20:24 UTC physics.info [Source type: Academic]

^ The speed of sound in a medium is given by: .
  • The Sounds of Teacups and Glasses 14 January 2010 20:24 UTC www.drphysics.com [Source type: FILTERED WITH BAYES]

^ Sound waves do not travel at the same speed through gases, liquids, and solids.
  • NASA Quest > Aerospace Team Online 14 January 2010 20:24 UTC quest.arc.nasa.gov [Source type: Original source]

.In dry air at 20 °C (68 °F), the speed of sound is 343 meters per second (1,125 ft/s).^ Speed in feet per second .

^ The SI unit of speed and velocity is the meter per second .
  • Speed & Velocity - The Physics Hypertextbook 14 January 2010 20:24 UTC physics.info [Source type: FILTERED WITH BAYES]

^ Speed in meters per second .

.This equates to 1,236 kilometers per hour (768 mph), or about one kilometer in three seconds and about one mile in five seconds.^ One meter per second is 3.6 kilometers-per-hour and 2.2374 miles-per-hour.
  • 3D sound effect for 3D Rad 14 January 2010 20:24 UTC www.3drad.com [Source type: Reference]

^ Sound waves travel one mile in about five seconds.
  • Snowmobiling Fact book: Sound- ISMA (International Snowmobile Manufacturers Association)-Information for snowmobilers: snowmobiling trails and safety; facts and trends 14 January 2010 20:24 UTC www.snowmobile.org [Source type: FILTERED WITH BAYES]

^ That means it travels about one mile in five seconds!
  • NASA Quest > Aerospace Team Online 14 January 2010 20:24 UTC quest.arc.nasa.gov [Source type: Original source]

.This figure for air (or any given gas) increases with gas temperature (equations are given below), but is much less dependent of pressure or density for a given gas.^ The air pressure and the density of air (air density) are proportional to each other at the same temperature.
  • Speed of sound in air and the temperature calculator air pressure - table density of air calculation acoustic impedance air density sea level velocity ideal gas 20 degrees or 21 degrees Celsius C - sengpielaudio Sengpiel Berlin 14 January 2010 20:24 UTC www.sengpielaudio.com [Source type: Academic]

^ The speed of sound is dependent on the density of the air and the density of the air is dependent on the temperature of the air.
  • Calculate Speed of Sound wave - Online Physics Calculators 14 January 2010 20:24 UTC www.easycalculation.com [Source type: Academic]

^ Notice: Air pressure p and air density ρ are not the same.
  • Speed of sound in air and the temperature calculator air pressure - table density of air calculation acoustic impedance air density sea level velocity ideal gas 20 degrees or 21 degrees Celsius C - sengpielaudio Sengpiel Berlin 14 January 2010 20:24 UTC www.sengpielaudio.com [Source type: Academic]

.For different gases, the speed of sound is dependent on the mean molecular weight of the gas, and to a lesser extent upon the ways in which the molecules of the gas can store heat energy from compression (since sound in gases is a type of compression).^ The speed of sound for various gases at 0° C: .
  • Speed of Sound in a Gas - Succeed in Understanding Physics: School for Champions 14 January 2010 20:24 UTC www.school-for-champions.com [Source type: FILTERED WITH BAYES]

^ To demonstrate the dependance of the velocity of sound upon the density of the carrier gas.
  • Wa-5 Speed of Sound (Density Dependence) : Wave properties : Wave motion : Home : Physics Lecture Demo : The University of Melbourne 14 January 2010 20:24 UTC lecturedemo.ph.unimelb.edu.au [Source type: Academic]

^ The speed of sound in a gas is a function of its temperature.
  • Speed of Sound in a Gas - Succeed in Understanding Physics: School for Champions 14 January 2010 20:24 UTC www.school-for-champions.com [Source type: FILTERED WITH BAYES]

.The speed of sound in air is referred to as Mach 1 by aerospace physics.^ Sound Speed [at 20°C in dry air] .
  • Atmospheric Science Program, UC Davis 14 January 2010 20:24 UTC atm.ucdavis.edu [Source type: Academic]

^ What is the speed of sound in air?
  • Speed of sound in air and the temperature calculator air pressure - table density of air calculation acoustic impedance air density sea level velocity ideal gas 20 degrees or 21 degrees Celsius C - sengpielaudio Sengpiel Berlin 14 January 2010 20:24 UTC www.sengpielaudio.com [Source type: Academic]

^ In air, the speed of sound at 20C is 343ms -1 .
  • Speed of Sound - DiracDelta Science & Engineering Encyclopedia 14 January 2010 20:24 UTC www.diracdelta.co.uk [Source type: Academic]

.Although "the speed of sound" is commonly used to refer specifically to the speed of sound waves in air, the speed of sound can be measured in virtually any substance.^ Measurement at speed of sound .
  • ISA | Measurement at speed of sound 14 January 2010 20:24 UTC www.isa.org [Source type: Academic]

^ It is the specific number used to measure Film Speed .

^ What causes the SPEED of a sound wave?

.Sound travels faster in liquids and non-porous solids (5,120 m/s in iron) than it does in air, traveling about 4.3 times faster in water (1,484 m/s) than in air at 20 degrees Celsius.^ Sound Speed [at 20°C in dry air] .
  • Atmospheric Science Program, UC Davis 14 January 2010 20:24 UTC atm.ucdavis.edu [Source type: Academic]

^ Sound can also travel through solids and liquids, not just gases.
  • Lesson 49: Properties of Sound 14 January 2010 20:24 UTC www.studyphysics.ca [Source type: FILTERED WITH BAYES]

^ Reflecting Excellence Kids ask: Why does sound travel faster in water?
  • Daily Herald | Kids ask: Why does sound travel faster in water? 14 January 2010 20:24 UTC www.dailyherald.com [Source type: General]

.Additionally, in solids, there occurs the possibility of two different types of sound waves: one type (called "longitudinal waves" when in solids) is associated with compression (the same as all sound waves in fluids) and the other is associated with shear stresses, which cannot occur in fluids.^ This is called a longitudinal or compression wave .
  • Lab III-9 Waves: Speed of Sound 14 January 2010 20:24 UTC web.me.com [Source type: FILTERED WITH BAYES]

^ We also restrict ourselves to sound in a fluid medium, which cannot support shear stresses.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ Sound is a longitudinal wave.
  • Lesson 49: Properties of Sound 14 January 2010 20:24 UTC www.studyphysics.ca [Source type: FILTERED WITH BAYES]

.These two types of waves have different speeds, and (for example in an earthquake) may thus be initiated at the same time but arrive at distant points at appreciably different times.^ These two waves have the same frequency but different amplitudes.
  • NOAA Ocean Explorer: Sound in the Sea: Background 14 January 2010 20:24 UTC oceanexplorer.noaa.gov [Source type: FILTERED WITH BAYES]

^ These two waves have the same amplitude but different frequencies.
  • NOAA Ocean Explorer: Sound in the Sea: Background 14 January 2010 20:24 UTC oceanexplorer.noaa.gov [Source type: FILTERED WITH BAYES]

^ High speed ferries operate under the same right-of-way rules that all boats must obey. Recreational boaters that may have forgotten these rules should relearn them in then interest of total boating safety.
  • Home Page 14 January 2010 20:24 UTC fastferryinfo.org [Source type: FILTERED WITH BAYES]

.The speed of compression-type waves in all media is set by the medium's compressibility and density, and the speed of shear waves in solids is set by the material's rigidity, compressibility and density.^ A medium is a material (solid, liquid or gas) which a wave travels through.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

^ The density of the medium will affect the speed the wave will travel at.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

^ B y e r i n M c n a l l y Mechanical waves are waves which propagate through a material medium (solid, liquid or gas) at a speed which depends on the elastic and inertial properties of the medium.

Contents

Basic concept

.
U.S. Navy F/A-18 breaking the sound barrier.
^ Was the German jet interceptor Messerschmidt 262 the first airplane in the world to break the sound barrier?
  • TR 1/2003: A. Chelain: Was the Me262 the First Airplane to Break the Sound Barrier? 14 January 2010 20:24 UTC vho.org [Source type: FILTERED WITH BAYES]

^ The battle to break the sound barrier on land was won exactly 50 years after Chuck Yeager broke it in the air ...
  • NOVA Online | Faster Than Sound | Speed Machines 14 January 2010 20:24 UTC www.pbs.org [Source type: News]

^ In early September of 1997, the stage was finally set for the ultimate car race — to be the first to officially break the sound barrier in a race car.
  • ThrustSSC - The fastest car in the world 14 January 2010 20:24 UTC www.roadsters.com [Source type: News]

.The white halo is formed by condensed water droplets, a result of sudden drop in air pressure behind the shock cone around the aircraft (see Prandtl-Glauert singularity).^ To describe the first perturbation, a decrease in pressure due to the ionization part in the reflected shock structure, the flow equations are linearized but the rate equations are used in nonlinear form.
  • Crespo-Martinez, Antonio (1968-05-07) I. Theoretical investigation of the reflection of ionizing shocks. II. Theoretical study of sound and shock waves in a two-phase flow. http://resolver.caltech.edu/CaltechETD:etd-05102005-094142 14 January 2010 20:24 UTC etd.caltech.edu [Source type: Academic]

^ If the humidity level is high enough (e.g., just above sea surface on a warm Pacific Ocean afternoon), the humidity in the air may condense in that trough of low pressure and form a cloud, only to be reabsorbed by the air when pressure returns to normal.
  • Pictures of the sound barrier-Disputed! 14 January 2010 20:24 UTC www.truthorfiction.com [Source type: FILTERED WITH BAYES]

^ A key sensor is a pitot tube protruding from the nose cone, which has small air inlets that are used to measure air pressure and thus airspeed.
  • Vehicle Positioning with GNSS — at the Speed of Sound | Inside GNSS 14 January 2010 20:24 UTC www.insidegnss.com [Source type: FILTERED WITH BAYES]

[1][2]
.The transmission of sound can be illustrated by using a toy model consisting of an array of balls interconnected by springs.^ Two models exist: One for straight cuts used for picture, and one for slanted cuts used for sound.

^ It will be useful to think of a model where the air molecules are connected to each other by springs, as indicated in the above figure.

^ Replacement transformer for sound conditioner model #1200A. 110/120 volt for domestic use.
  • Get Sound Screen Sleep Mate Sound Machines, White Noise Conditioners, Sleep Machines from Marpac offering the SleepMate, Sound Screen, and the Marsona 14 January 2010 20:24 UTC www.marpac.com [Source type: FILTERED WITH BAYES]

.For real material the balls represent molecules and the springs represent the bonds between them.^ More molecules are squeezed into the same volume, therefore, the molecules are closer together and their bonds are stronger (think tight springs).
  • The Speed of Sound in Other Materials 14 January 2010 20:24 UTC www.ndt-ed.org [Source type: FILTERED WITH BAYES]

^ Since sound is more easily transmitted between particles with strong bonds (tight springs), sound travels faster through denser air.
  • The Speed of Sound in Other Materials 14 January 2010 20:24 UTC www.ndt-ed.org [Source type: FILTERED WITH BAYES]

^ In general, the bond strength between particles is strongest in solid materials and is weakest in the gaseous state.
  • The Speed of Sound in Other Materials 14 January 2010 20:24 UTC www.ndt-ed.org [Source type: FILTERED WITH BAYES]

.Sound passes through the model by compressing and expanding the springs, transmitting energy to neighboring balls, which transmit energy to their springs, and so on.^ Only through his skill in compositional development do the motivic fragments remain fresh with each passing measure - while preserving the characteristic sound of SPEED RACER. .
  • ScoreKeeper Talks About Michael Giacchino's SPEED RACER Music!! -- Ain't It Cool News: The best in movie, TV, DVD, and comic book news. 14 January 2010 20:24 UTC www.aintitcool.com [Source type: General]

^ This has the important consequence that microscopic rotational motion cannot arise if it was initially absent (as is the case when a sound wave passes through the medium).
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ As mentioned at the beginning of this document, sound can be altered by its immediate environment and any further physical mediums it passes through after initial excitation.
  • JISC Digital Media - Audio: The Physical Principles of Sound 14 January 2010 20:24 UTC www.jiscdigitalmedia.ac.uk [Source type: FILTERED WITH BAYES]

.The speed of sound through the model depends on the stiffness of the springs (stiffer springs transmit energy more quickly).^ Speed of Sound through Materials Velocity of Materials .
  • Velocity Materials Speed of Sound through Materials Velocity of Materials 14 January 2010 20:24 UTC www.bamr.co.za [Source type: Academic]

^ The sound is transmitted much more quickly."
  • Daily Herald | Kids ask: Why does sound travel faster in water? 14 January 2010 20:24 UTC www.dailyherald.com [Source type: General]

^ The speed of sound can vary, depending on the material through which the sound waves move.

.Effects like dispersion and reflection can also be understood using this model.^ One tricky thing is that as you can see in the table, all 16 possible effects are used, so we have no extra value to use for no-effect like we do with notes and samples.
  • Sound Mixing - Deku's Tree of Art 14 January 2010 20:24 UTC deku.rydia.net [Source type: FILTERED WITH BAYES]

^ Detailed car models, well designed tracks, damage effects (like an engine catching fire), and there is very little, if any, pop up.
  • Spirit of Speed 1937 Review (Dreamcast) - Gaming Age 14 January 2010 20:24 UTC www.gaming-age.com [Source type: General]

^ Non-literal Effects - are sounds used to indicate an event, without being "like" the actual sound of it.

.In a real material, the stiffness of the springs is called the elastic modulus, and the mass corresponds to the density.^ Elastic Properties and Young Modulus for some Materials Young Modulus (Tensile Modulus) for common materials - steel, glass, wood and more ..

^ Speed of Sound in some common Solids Elastic Properties and Young Modulus for some Materials The Bulk Modulus for Elasticity Material Properties Subsonic and Supersonic speed .

^ FIG. 4 shows the bulk modulus, density, and sound speed for a number of granular materials; .
  • Low sound speed damping materials and methods of use - Patent 6237302 23 September 2009 2:36 UTC www.freepatentsonline.com [Source type: Academic]

.All other things being equal, sound will travel more slowly in denser materials, and faster in stiffer ones.^ Traveling Faster than Sound .
  • Traveling Faster than Sound - Succeed in Understanding Physics: School for Champions 14 January 2010 20:24 UTC www.school-for-champions.com [Source type: General]

^ A sound wave will travel faster in a less dense material than a more dense material.

^ A sound wave will travel faster in a less dense material rather than in a more dense material.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

.For instance, sound will travel much faster in steel than soft iron, due to the greater stiffness of steel at about the same density.^ Traveling Faster than Sound .
  • Traveling Faster than Sound - Succeed in Understanding Physics: School for Champions 14 January 2010 20:24 UTC www.school-for-champions.com [Source type: General]

^ Depending on the density of the medium, sound travels through some mediums faster than others.
  • Some Basic Principles 14 January 2010 20:24 UTC harada-sound.com [Source type: FILTERED WITH BAYES]

^ Dislocations Faster than the Speed of Sound .
  • Dislocations Faster than the Speed of Sound -- Gumbsch and Gao 283 (5404): 965 -- Science 14 January 2010 20:24 UTC www.sciencemag.org [Source type: Academic]

.Similarly, sound travels about \sqrt{2} = about 1.41 times faster in light hydrogen (protium) gas than in heavy hydrogen (deuterium) gas, since deuterium has similar properties but twice the density.^ Dark is also heavier than light.
  • speed of dark 14 January 2010 20:24 UTC www.freakface.com [Source type: Original source]

^ The speed of sound is about a million times slower than the speed of light.
  • 03.04.03: Physics of Sound: How We Hear Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: FILTERED WITH BAYES]

^ Traveling Faster than Sound .
  • Speed of Sound in a Gas - Succeed in Understanding Physics: School for Champions 14 January 2010 20:24 UTC www.school-for-champions.com [Source type: FILTERED WITH BAYES]
  • Traveling Faster than Sound - Succeed in Understanding Physics: School for Champions 14 January 2010 20:24 UTC www.school-for-champions.com [Source type: General]

.At the same time, "compression-type" sound will travel faster in solids than in liquids, and faster in liquids than in gases, because the solids are more difficult to compress than liquids, while liquids in turn are more difficult to compress than gases.^ Sound can also travel through solids and liquids, not just gases.
  • Lesson 49: Properties of Sound 14 January 2010 20:24 UTC www.studyphysics.ca [Source type: FILTERED WITH BAYES]

^ As a result, sound waves travel faster is solids than in liquids, and faster in liquids than in gasses.
  • The Speed of Sound in Other Materials 14 January 2010 20:24 UTC www.ndt-ed.org [Source type: FILTERED WITH BAYES]

^ Traveling Faster than Sound .
  • Speed of Sound in a Gas - Succeed in Understanding Physics: School for Champions 14 January 2010 20:24 UTC www.school-for-champions.com [Source type: FILTERED WITH BAYES]

.Some textbooks mistakenly state that the speed of sound increases with increasing density.^ Air density or density of air ρ , air impedance Z , speed of sound c .
  • Speed of sound in air and the temperature calculator air pressure - table density of air calculation acoustic impedance air density sea level velocity ideal gas 20 degrees or 21 degrees Celsius C - sengpielaudio Sengpiel Berlin 14 January 2010 20:24 UTC www.sengpielaudio.com [Source type: Academic]

^ State your value for the speed of sound.
  • The Science House - Speed of Sound 14 January 2010 20:24 UTC www.science-house.org [Source type: FILTERED WITH BAYES]

^ Several homogeneous Lodengraf™ materials are identified in FIG. 4, all of which have sound speeds near 100 m/s (although their densities range over three orders of magnitude).
  • Low sound speed damping materials and methods of use - Patent 6237302 23 September 2009 2:36 UTC www.freepatentsonline.com [Source type: Academic]

.This is usually illustrated by presenting data for three materials, such as air, water and steel, which also have vastly different compressibilities which more than make up for the density differences.^ Suppose that two volumes of a substance such as air have different densities.
  • The Speed of Sound in Other Materials 14 January 2010 20:24 UTC www.ndt-ed.org [Source type: FILTERED WITH BAYES]

^ Also, the density of air was neglected compared to that of water.
  • The Sounds of Teacups and Glasses 14 January 2010 20:24 UTC www.drphysics.com [Source type: FILTERED WITH BAYES]

^ The more the air is compressed, the greater the error.
  • Measuring and Calculating Air Speed: 14 January 2010 20:24 UTC womanpilot.com [Source type: FILTERED WITH BAYES]

.An illustrative example of the two effects is that sound travels only 4.3 times faster in water than air, despite enormous differences in compressibility of the two media.^ Traveling Faster than Sound .
  • Speed of Sound in a Gas - Succeed in Understanding Physics: School for Champions 14 January 2010 20:24 UTC www.school-for-champions.com [Source type: FILTERED WITH BAYES]

^ Sound travels faster through solids than liquids and faster through liquids than gases.
  • 03.04.03: Physics of Sound: How We Hear Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: FILTERED WITH BAYES]

^ Kids ask: Why does sound travel faster in water?
  • Daily Herald | Kids ask: Why does sound travel faster in water? 14 January 2010 20:24 UTC www.dailyherald.com [Source type: General]

.The reason is that the larger density of water, which works to slow sound in water relative to air, nearly makes up for the compressibility in the two media.^ Also, the density of air was neglected compared to that of water.
  • The Sounds of Teacups and Glasses 14 January 2010 20:24 UTC www.drphysics.com [Source type: FILTERED WITH BAYES]

^ Slow down or speed up the sounds.

^ We discussed sound waves as waves of compression in air.

Basic formula

In general, the speed of sound c is given by
 c = \sqrt{\frac{C}{\rho}}
where
C is a coefficient of stiffness, the bulk modulus (or the modulus of bulk elasticity for gas mediums),
ρ is the density
.Thus the speed of sound increases with the stiffness (the resistance of an elastic body to deformation by an applied force) of the material, and decreases with the density.^ Thus the speed of sound increases with the stiffness of the material.
  • Speed of sound in air and the temperature calculator air pressure - table density of air calculation acoustic impedance air density sea level velocity ideal gas 20 degrees or 21 degrees Celsius C - sengpielaudio Sengpiel Berlin 14 January 2010 20:24 UTC www.sengpielaudio.com [Source type: Academic]

^ Approximate speed of sound in common materials .
  • Speed of sound in air and the temperature calculator air pressure - table density of air calculation acoustic impedance air density sea level velocity ideal gas 20 degrees or 21 degrees Celsius C - sengpielaudio Sengpiel Berlin 14 January 2010 20:24 UTC www.sengpielaudio.com [Source type: Academic]

^ As the speed decreases, the amplitude increases.

For general equations of state, if classical mechanics is used, the speed of sound c is given by
 c^2=\frac{\partial p}{\partial\rho}
where differentiation is taken with respect to adiabatic change.
.If relativistic effects are important, the speed of sound may be calculated from the relativistic Euler equations.^ What is the equation for the speed of sound in any gas?
  • Speed of Sound in a Gas - Succeed in Understanding Physics: School for Champions 14 January 2010 20:24 UTC www.school-for-champions.com [Source type: FILTERED WITH BAYES]

^ Calculate the speed of sound.

^ Calculating the speed of sound .
  • Speed of Sound in a Gas - Succeed in Understanding Physics: School for Champions 14 January 2010 20:24 UTC www.school-for-champions.com [Source type: FILTERED WITH BAYES]

.In a non-dispersive medium sound speed is independent of sound frequency, so the speeds of energy transport and sound propagation are the same.^ The speed of sound in a medium is given by: .
  • The Sounds of Teacups and Glasses 14 January 2010 20:24 UTC www.drphysics.com [Source type: FILTERED WITH BAYES]

^ The speed of sound is often confused with the frequency of a sound.
  • 03.04.03: Physics of Sound: How We Hear Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: FILTERED WITH BAYES]

^ Sound propagates through the medium with a speed independent of the motions of source and observer, of course.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

.For audible sounds air is a non-dispersive medium.^ Air, for example, is a sound medium.

^ Photo: You'll only hear an alarm clock if there's air or some other medium to carry its sound to your ears.
  • How sound works: A simple introduction to the science of sound for kids 14 January 2010 20:24 UTC www.explainthatstuff.com [Source type: General]

^ The medium need not be air; metal, wood, stone, glass, water, and many other substances conduct sound, many of them better than air.

.But air does contain a small amount of CO2 which is a dispersive medium, and it introduces dispersion to air at ultrasonic frequencies (> 28 kHz).^ A precise value of c = 331.46 m/s for dry air containing 0.03% CO 2 at 0 °C is given in tables, but the actual velocity is affected by vibrational relaxation in O 2 , the presence of H 2 O, and other small factors, so the precision is somewhat illusory.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ This implies that when a sound moves from air to water or vice versa, the frequency of the sound will be the same in each medium.

^ For the lowest frequencies, the maximum amplitude as measured by the microphone does not occur at the position of the loudspeaker, but a noticeable and measurable amount down the tube away from it.

[3]
.In a dispersive medium sound speed is a function of sound frequency, through the dispersion relation.^ Divide the speed of sound by the frequency (in hz) and divide again by 2.
  • Wind Instrument Mathematics 14 January 2010 20:24 UTC www.mimf.com [Source type: FILTERED WITH BAYES]

^ The speed of sound in a medium is given by: .
  • The Sounds of Teacups and Glasses 14 January 2010 20:24 UTC www.drphysics.com [Source type: FILTERED WITH BAYES]

^ Speed of sound in various mediums .

The spatial and temporal distribution of a propagating disturbance will continually change. .Each frequency component propagates at its own phase velocity, while the energy of the disturbance propagates at the group velocity.^ Each component has a distinct frequency, amplitude and phase.
  • JISC Digital Media - Audio: The Physical Principles of Sound 14 January 2010 20:24 UTC www.jiscdigitalmedia.ac.uk [Source type: FILTERED WITH BAYES]

^ Multiple frequencies will combine in the air, creating a complex mix of sound, the nature of which depends upon the ratios of energy and phase of the combined sounds.
  • Measurement and Characterization of Sound Systems Sound System Characterization and Measurement 14 January 2010 20:24 UTC digitalcontentproducer.com [Source type: FILTERED WITH BAYES]

^ This key piece of mathematics proved that any sound was a combination of various singular frequency components in a mix of relative levels and phases.
  • Measurement and Characterization of Sound Systems Sound System Characterization and Measurement 14 January 2010 20:24 UTC digitalcontentproducer.com [Source type: FILTERED WITH BAYES]

.The same phenomenon occurs with light waves; see optical dispersion for a description.^ Doppler effect the phenomenon, called the Doppler Effect, is a shift in the frequency and wavelength of waves, including sound and light, resulting from relative motion between the source of the wave and the medium.
  • Physics of sound 14 January 2010 20:24 UTC www.educypedia.be [Source type: Academic]

^ From our construction, we see that the incident and refracted wave normals, and the normal to the interface, all lie in the same plane, the plane of incidence .
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ In answer to the question of the speed of Light and Gravity - yes, they are the same, as they are simply the velocity of the Spherical In-Waves flowing through Space.
  • Speed of Gravity / Speed of Light 14 January 2010 20:24 UTC www.spaceandmotion.com [Source type: FILTERED WITH BAYES]

Dependence on the properties of the medium

.The speed of sound is variable and depends on the properties of the substance through of which the wave is travelling.^ Speed of Sound through Materials Velocity of Materials .
  • Velocity Materials Speed of Sound through Materials Velocity of Materials 14 January 2010 20:24 UTC www.bamr.co.za [Source type: Academic]

^ The speed of sound for various gases at 0° C: .
  • Speed of Sound in a Gas - Succeed in Understanding Physics: School for Champions 14 January 2010 20:24 UTC www.school-for-champions.com [Source type: FILTERED WITH BAYES]

^ Speed of sound in various mediums .

.In solids, the speed of longitudinal waves depend on the stiffness to tensile stress, and the density of the medium.^ The speed of any wave depends upon the properties of the medium through which the wave is traveling.
  • The Speed of Sound 14 January 2010 20:24 UTC www.physicsclassroom.com [Source type: FILTERED WITH BAYES]
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

^ Speed and attenuation of waves in solids .
  • The speed and attenuation of sound 2.4.1 14 January 2010 20:24 UTC www.kayelaby.npl.co.uk [Source type: Academic]

^ The density of the medium will affect the speed the wave will travel at.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

.In fluids, the medium's compressibility and density are the important factors.^ The density and compressibility of the composite medium are where the a  and w  subscripts refer to air and water, respectively.
  • The Sounds of Teacups and Glasses 14 January 2010 20:24 UTC www.drphysics.com [Source type: FILTERED WITH BAYES]

^ Compressibility of a fluid directly relates to the speed of sound and density of the fluid.
  • ISA | Measurement at speed of sound 14 January 2010 20:24 UTC www.isa.org [Source type: Academic]

^ The speed of dilatational waves in unbounded fluids is c = (β a ρ ) −1/2 , β a being the adiabatic compressibility and ρ the density.
  • The speed and attenuation of sound 2.4.1 14 January 2010 20:24 UTC www.kayelaby.npl.co.uk [Source type: Academic]

.In gases, compressibility and density are related, making other compositional effects and properties important, such as temperature and molecular composition.^ In non-ideal gases, such as a van der Waals gas, the proportionality is not exact, and there is a slight dependence on the gas pressure, even at a constant temperature.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ Although the equation for the speed of sound (speed = frequency x wavelength) is constant, the speed is affected by the medium through which the sound waves are propagated, as well as other conditions such as temperature and humidity.
  • Fascinating Facts About The Speed Of Sound 14 January 2010 20:24 UTC www.proavmagazine.com [Source type: General]

^ For example, in low molecular weight gases, such as helium, sound propagates faster compared to heavier gases, such as xenon.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

.In low molecular weight gases, such as helium, sound propagates faster compared to heavier gases, such as xenon (for monatomic gases the speed of sound is about 68% of the mean speed that molecules move in the gas).^ The speed of sound for various gases at 0° C: .
  • Speed of Sound in a Gas - Succeed in Understanding Physics: School for Champions 14 January 2010 20:24 UTC www.school-for-champions.com [Source type: FILTERED WITH BAYES]

^ What happens when the object moves at the speed of sound?
  • Traveling Faster than Sound - Succeed in Understanding Physics: School for Champions 14 January 2010 20:24 UTC www.school-for-champions.com [Source type: General]

^ The speed of sound in a gas is a function of its temperature.
  • Speed of Sound in a Gas - Succeed in Understanding Physics: School for Champions 14 January 2010 20:24 UTC www.school-for-champions.com [Source type: FILTERED WITH BAYES]

.For a given ideal gas the sound speed depends only on its temperature.^ The speed of sound in a medium is given by: .
  • The Sounds of Teacups and Glasses 14 January 2010 20:24 UTC www.drphysics.com [Source type: FILTERED WITH BAYES]

^ The speed of sound in air actually depends on the temperature of the air.
  • Lesson 49: Properties of Sound 14 January 2010 20:24 UTC www.studyphysics.ca [Source type: FILTERED WITH BAYES]

^ The speed of sound in a gas is a specific fraction of the average speed of the gas molecules at the given temperature.
  • Speed of Sound in a Gas - Succeed in Understanding Physics: School for Champions 14 January 2010 20:24 UTC www.school-for-champions.com [Source type: FILTERED WITH BAYES]

.At a constant temperature, the ideal gas pressure has no effect on the speed of sound, because pressure and density (also proportional to pressure) have equal but opposite effects on the speed of sound, and the two contributions cancel out exactly.^ The speed of sound is not influenced by the temperature.

^ The speed of sound decreases as the temperature increases.

^ Increasing the pressure increases the speed of sound and shifts the maximum to higher temperatures, both in line with the effect on the density.
  • Explanation of the Density Anomalies of Water (D1-D19) 14 January 2010 20:24 UTC www.lsbu.ac.uk [Source type: Academic]

.In a similar way, compression waves in solids depend both on compressibility and density—just as in liquids—but in gases the density contributes to the compressibility in such a way that some part of each attribute factors out, leaving only a dependence on temperature, molecular weight, and heat capacity (see derivations below).^ Sound can also travel through solids and liquids, not just gases.
  • Lesson 49: Properties of Sound 14 January 2010 20:24 UTC www.studyphysics.ca [Source type: FILTERED WITH BAYES]

^ They compress and form a shock wave (see “Piling On,” below).
  • Mach 1: Assaulting the Barrier | History of Flight | Air & Space Magazine 14 January 2010 20:24 UTC www.airspacemag.com [Source type: FILTERED WITH BAYES]

^ In non-ideal gases, such as a van der Waals gas, the proportionality is not exact, and there is a slight dependence on the gas pressure, even at a constant temperature.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

.Thus, for a single given gas (where molecular weight does not change) and over a small temperature range (where heat capacity is relatively constant), the speed of sound becomes dependent on only the temperature of the gas.^ The speed of sound in air actually depends on the temperature of the air.
  • Lesson 49: Properties of Sound 14 January 2010 20:24 UTC www.studyphysics.ca [Source type: FILTERED WITH BAYES]

^ The correct answer is: The speed of sound does not depend on air pressure, but on temperature.
  • Speed of sound in air and the temperature calculator air pressure - table density of air calculation acoustic impedance air density sea level velocity ideal gas 20 degrees or 21 degrees Celsius C - sengpielaudio Sengpiel Berlin 14 January 2010 20:24 UTC www.sengpielaudio.com [Source type: Academic]

^ What is the equation for the speed of sound in any gas?
  • Speed of Sound in a Gas - Succeed in Understanding Physics: School for Champions 14 January 2010 20:24 UTC www.school-for-champions.com [Source type: FILTERED WITH BAYES]

.In non-ideal gases, such as a van der Waals gas, the proportionality is not exact, and there is a slight dependence of sound velocity on the gas pressure.^ In non-ideal gases, such as a van der Waals gas, the proportionality is not exact, and there is a slight dependence on the gas pressure, even at a constant temperature.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ In a given ideal gas the speed of sound depends only on its temperature.
  • Speed of sound in air and the temperature calculator air pressure - table density of air calculation acoustic impedance air density sea level velocity ideal gas 20 degrees or 21 degrees Celsius C - sengpielaudio Sengpiel Berlin 14 January 2010 20:24 UTC www.sengpielaudio.com [Source type: Academic]

^ In a given ideal gas the sound speed depends only on its temperature.
  • Speed of sound in air and the temperature calculator air pressure - table density of air calculation acoustic impedance air density sea level velocity ideal gas 20 degrees or 21 degrees Celsius C - sengpielaudio Sengpiel Berlin 14 January 2010 20:24 UTC www.sengpielaudio.com [Source type: Academic]
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

.Humidity has a small, but measurable effect on sound speed (causing it to increase by about 0.1%-0.6%), because oxygen and nitrogen molecules of the air are replaced by lighter molecules of water.^ Measurement at speed of sound .
  • ISA | Measurement at speed of sound 14 January 2010 20:24 UTC www.isa.org [Source type: Academic]

^ Calculate the speed of sound in air for each of the measurements you made.

^ What is the speed of sound in air?
  • Speed of sound in air and the temperature calculator air pressure - table density of air calculation acoustic impedance air density sea level velocity ideal gas 20 degrees or 21 degrees Celsius C - sengpielaudio Sengpiel Berlin 14 January 2010 20:24 UTC www.sengpielaudio.com [Source type: Academic]

This is a simple mixing effect.

Implications for atmospheric acoustics

.In the Earth's atmosphere, the most important factor affecting the speed of sound is the temperature (see Details below).^ The speed of sound is not influenced by the temperature.

^ The speed of sound decreases as the temperature increases.

^ The speed of sound in a gas is a function of its temperature.
  • Speed of Sound in a Gas - Succeed in Understanding Physics: School for Champions 14 January 2010 20:24 UTC www.school-for-champions.com [Source type: FILTERED WITH BAYES]

.Since temperature and thus the speed of sound normally decrease with increasing altitude, sound is refracted upward, away from listeners on the ground, creating an acoustic shadow at some distance from the source.^ The speed of sound in a gas is a function of its temperature.
  • Speed of Sound in a Gas - Succeed in Understanding Physics: School for Champions 14 January 2010 20:24 UTC www.school-for-champions.com [Source type: FILTERED WITH BAYES]

^ The presence of a tailwind or headwind will increase or decrease the ground speed.
  • Measuring and Calculating Air Speed: 14 January 2010 20:24 UTC womanpilot.com [Source type: FILTERED WITH BAYES]

^ Sound speed is the source of this information.
  • Dispersion Technology, Inc.- Instruments for Characterizing Concentrated Colloidal Dispersions. 23 September 2009 2:36 UTC www.dispersion.com [Source type: Academic]

[4] .The decrease of the sound speed with height is referred to as a negative sound speed gradient.^ The speed of sound decreases as the temperature increases.

^ The speed of sound increases as the temperature decreases.

^ This is a wind shear , that can be expressed by a gradient dU/dy, where U is the wind speed and y is the height.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

.However, in the stratosphere, the speed of sound increases with height due to heating within the ozone layer, producing a positive sound speed gradient.^ The speed of sound decreases as the temperature increases.

^ The speed of sound increases as the temperature decreases.

^ The speed of sound increases as the temperature increases.

Practical formula for dry air

The approximate speed of sound in dry (0% humidity) air, in meters per second (m·s−1), at temperatures near 0 °C, can be calculated from:
 c_{\mathrm{air}} = (331{.}3 + (0{.}606^{\circ}\mathrm{C}^{-1} \cdot \vartheta)) \ \mathrm{m \cdot s^{-1}}\,
where .\vartheta is the temperature in degrees Celsius (°C).^ T is the temperature of the air in degrees Celsius.

^ For example, zero degrees Celsius is equal to 273 K. The ratio of the local temperature to that of SSL is called theta or q.
  • Measuring and Calculating Air Speed: 14 January 2010 20:24 UTC womanpilot.com [Source type: FILTERED WITH BAYES]

^ At normal atmospheric pressure and a temperature of 20 degrees Celsius, a sound wave will travel at approximately 343 m/s; this is approximately equal to 750 miles/hour.

This equation is derived from the first two terms of the Taylor expansion of the following more accurate equation:
c_{\mathrm{air}} = 331.3 \mathrm{m \cdot s^{-1}} \sqrt{1+\frac{\vartheta}{273.15\;^{\circ}\mathrm{C}}}
.The value of 331.3 m/s, which represents the 0 °C speed, is based on theoretical (and some measured) values of the heat capacity ratio, γ, as well as on the fact that at 1 atm real air is very well described by the ideal gas approximation.^ In fact, its a very real and very common scenario.
  • The Court Reporting Students' Online Support Center 14 January 2010 20:24 UTC www.his.com [Source type: General]

^ The result is a value that closely approximates the measured speed of light.
  • Molecular Expressions Microscopy Primer: Physics of Light and Color - Speed of Light 14 January 2010 20:24 UTC micro.magnet.fsu.edu [Source type: FILTERED WITH BAYES]

^ This dependence also applies to air, in good approximation and can be regarded as an ideal gas.
  • Speed of sound in air and the temperature calculator air pressure - table density of air calculation acoustic impedance air density sea level velocity ideal gas 20 degrees or 21 degrees Celsius C - sengpielaudio Sengpiel Berlin 14 January 2010 20:24 UTC www.sengpielaudio.com [Source type: Academic]

.Commonly found values for the speed of sound at 0 °C may vary from 331.2 to 331.6 due to the assumptions made when it is calculated.^ Calculate the speed of sound.

^ The speed of sound varies depending...

^ The speed of the sound wave varies with the temperature.

.If ideal gas γ is assumed to be 7/5 = 1.4 exactly, the 0 °C speed is calculated (see section below) to be 331.3 m/s, the coefficient used above.^ Find out exactly what you need to run your successful basketball speed camp with these useful, easy-to-use checklist.
  • Basketball, basketball speed, basketball workouts, basketball drills for speed.... 14 January 2010 20:24 UTC mybasketballspeed.com [Source type: General]

^ Is there a formula that I could use to calculate the needed RPM and diameter of a large rod that would approach the speed of light at the tip of the rod?
  • NASA's Cosmicopia -- Ask Us - General Physics - Speed of Light 14 January 2010 20:24 UTC helios.gsfc.nasa.gov [Source type: Original source]

^ The volume elasticity κ is used for generality, instead of γp for an ideal gas.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

.This equation is correct to a much wider temperature range, but still depends on the approximation of heat capacity ratio being independent of temperature, and will fail, particularly at higher temperatures.^ It is often the case that one can make approximations that apply over a limited region of reality, but that fail when we examine a larger range.
  • The speed of light is constant (from Einstein Light) 14 January 2010 20:24 UTC www.phys.unsw.edu.au [Source type: Original source]

^ I recently (September 2005) discovered that due to the approximate nature of the linearized equations this value is correct to the first order, but leads to an error for the wave momentum.
  • Plane Waves (Sound) 14 January 2010 20:24 UTC www.silcom.com [Source type: FILTERED WITH BAYES]

^ To a first order approximation, in this temperature range the speed of sound increases at a rate of 1 foot per second per degree Fahrenheit.
  • AN ANALYSIS OF RECORDED SOUNDS RELATING TO THE ASSASSINATION OF PRESIDENT JOHN F. KENNEDY 14 January 2010 20:24 UTC mcadams.posc.mu.edu [Source type: FILTERED WITH BAYES]

.It gives good predictions in relatively dry, cold, low pressure conditions, such as the Earth's stratosphere.^ The lunar orbit relative to Earth is a low eccentricity ellipse.

^ At resonance the pressure variation within the pipe becomes quite large, and a relatively low sound intensity results in a large variation in flame intensity.
  • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

.A derivation of these equations will be given in the following section.^ These are the basic equations of hydrodynamics, and are derived in any fluid mechanics text.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ As discussed in a previous unit , the mathematical relationship between speed, frequency and wavelength is given by the following equation.

^ The general equation for momentum flux is given in Table 3 of section 1.
  • Plane Waves (Sound) 14 January 2010 20:24 UTC www.silcom.com [Source type: FILTERED WITH BAYES]

Details

Speed in ideal gases and in air

For a gas, K (the bulk modulus in equations above, equivalent to C, the coefficient of stiffness in solids) is approximately given by
 K = \gamma \cdot p
thus
 c = \sqrt{\gamma \cdot {p \over \rho}}
Where:
γ is the adiabatic index also known as the isentropic expansion factor. .It is the ratio of specific heats of a gas at a constant-pressure to a gas at a constant-volume(Cp / Cv), and arises because a classical sound wave induces an adiabatic compression, in which the heat of the compression does not have enough time to escape the pressure pulse, and thus contributes to the pressure induced by the compression.^ The ratio of specific heats is related to the specific heat at constant pressure, c p , and the specific head at constant volume, c V , according to: .

^ Sound is a pressure wave pressure waves .
  • Physics of sound 14 January 2010 20:24 UTC www.educypedia.be [Source type: Academic]

^ We discussed sound waves as waves of compression in air.

p is the pressure.
ρ is the density
Using the ideal gas law to replace p with nRT/V, and replacing ρ with nM/V, the equation for an ideal gas becomes:
 c_{\mathrm{ideal}} = \sqrt{\gamma \cdot {p \over \rho}} = \sqrt{\gamma \cdot R \cdot T \over M}= \sqrt{\gamma \cdot k \cdot T \over m}
where
.
  • cideal is the speed of sound in an ideal gas.
  • R (approximately 8.3145 J·mol−1·K−1) is the molar gas constant.^ The speed of sound in a gas is proportional to the square root of its density.
    • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

    ^ The speed of sound v in a pure gas is related to the pressure p and the density of the gas by: .

    ^ Water temperature deep in the oceans is very nearly constant and in such regions the sound speed is dominated by its dependence on depth, sound speed increasing with increasing depth.
    • Underwater Acoustics 23 September 2009 2:36 UTC www.arc.id.au [Source type: Academic]

    [1]
  • .
  • k is the Boltzmann constant
  • γ (gamma) is the adiabatic index (sometimes assumed 7/5 = 1.400 for diatomic molecules from kinetic theory, assuming from quantum theory a temperature range at which thermal energy is fully partitioned into rotation (rotations are fully excited), but none into vibrational modes.^ As the temperature increases above 3.984°C, the cluster equilibrium shifts towards the more collapsed structure (for example, CS ), which reduces any increase in volume due to the increased kinetic energy of the molecules.
    • Explanation of the Density Anomalies of Water (D1-D19) 14 January 2010 20:24 UTC www.lsbu.ac.uk [Source type: Academic]

    ^ This is in contrast to normal liquids where the increasing kinetic energy of molecules and space available due to expansion, as the temperature is raised, means that it becomes less likely that molecules will be found close to each other.
    • Explanation of the Density Anomalies of Water (D1-D19) 14 January 2010 20:24 UTC www.lsbu.ac.uk [Source type: Academic]

    ^ A correct theory should enable us to calculate a zeta potential which remains constant over a wide concentration range.
    • Dispersion Technology, Inc.- Instruments for Characterizing Concentrated Colloidal Dispersions. 23 September 2009 2:36 UTC www.dispersion.com [Source type: Academic]

    .Gamma is actually experimentally measured over a range from 1.3991 to 1.403 at 0 degrees Celsius, for air.^ Temperature will affect the speed of sound-- in air, the speed of sound increases approximately .60 m/s for each degree Celsius: .
    • Some Basic Principles 14 January 2010 20:24 UTC harada-sound.com [Source type: FILTERED WITH BAYES]

    .Gamma is assumed from kinetic theory to be exactly 5/3 = 1.6667 for monoatomic molecules such as noble gases).
  • T is the absolute temperature in kelvins.
  • M is the molar mass in kilograms per mole.^ V is the volume, n the number of moles of the gas, R the gas constant, and T the temperature in Kelvin .

    ^ In this case, c may not vary exactly as the square root of the absolute temperature.
    • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

    ^ The units of the constant are given in units such as: liter atmospheres per mole Kelvin joules per mole Kelvin meter cubed atmospheres per mole Kelvin etc.

    The mean molar mass for dry air is about 0.0289645 kg/mol.
  • m is the mass of a single molecule in kilograms.
.This equation applies only when the sound wave is a small perturbation on the ambient condition, and the certain other noted conditions are fulfilled, as noted below.^ The pressure variations in a sound wave are so rapid, however, that there is no time to reach isothermal conditions.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ The way I thought of it was that time is only the movement of particles in relation to other particles, and came up with equations to measure this which showed how time changes relative to the object being measured.
  • DailyTech - German Scientists Declare Speed of Light Broken 14 January 2010 20:24 UTC www.dailytech.com [Source type: General]

^ The vibration of the air moves outward in all directions in the form of a wave.5 The following are examples of how certain sounds are produced.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

.Calculated values for cair have been found to vary slightly from experimentally determined values.^ FIG. 6 plots the measured sound speed for various mixtures of perlite and LDPE and compares these to theoretically calculated values; and .
  • Low sound speed damping materials and methods of use - Patent 6237302 23 September 2009 2:36 UTC www.freepatentsonline.com [Source type: Academic]

^ In the air as an example the sonorous waves are generated from variations of the pressure to of over and to of under of the static value of the atmospheric pressure.
  • Music and Sound Blog » 2009 » January 14 January 2010 20:24 UTC www.jjcaas.org [Source type: FILTERED WITH BAYES]

[5]
.Newton famously considered the speed of sound before most of the development of thermodynamics and so incorrectly used isothermal calculations instead of adiabatic.^ Speed of sound calculator.
  • http://www.vibrationdata.com/acoustics_page.htm 14 January 2010 20:24 UTC www.vibrationdata.com [Source type: Academic]

^ Mach number Main article: Mach number Mach number, a useful quantity in aerodynamics, is the ratio of an object's speed to the speed of sound in the medium through which it is passing (again, usually air).
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ The remaining few cases where the present analysis cannot be applied could be tested by the thermodynamic calculation of critical sound speeds using crossover equations of state in conjunction with experimentally determined critical isochoric heat capacities.
  • Can the Speed of Sound Be Used for Detecting Critical States of Fluid Mixtures? - The Journal of Physical Chemistry B (ACS Publications) 14 January 2010 20:24 UTC pubs.acs.org [Source type: Academic]

His result was missing the factor of γ but was otherwise correct.
.Numerical substitution of the above values gives the ideal gas approximation of sound velocity for gases, which is accurate at relatively low gas pressures and densities (for air, this includes standard Earth sea-level conditions).^ The speed of sound v in a pure gas is related to the pressure p and the density of the gas by: .

^ At 0 °C the speed of sound in distilled water is 1482 m/s, in sea water of 3.5% salinity 1522 m/s, in mercury 1450 m/s, in steel rails 5050 m/s, and in bulk soft iron 5957 m/s, which should give some idea of the range of phase velocities.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ At low pressures, absorption occurs when the wavelength becomes comparable to the molecular mean free path (about 66nm in air at STP).
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

.Also, for diatomic gases the use of \ \gamma\, = 1.4000 requires that the gas exist in a temperature range high enough that rotational heat capacity is fully excited (i.e., molecular rotation is fully used as a heat energy "partition" or reservoir); but at the same time the temperature must be low enough that molecular vibrational modes contribute no heat capacity (i.e., insigificant heat goes into vibration, as all vibrational quantum modes above the minimum-energy-mode, have energies too high to be populated by a significant number of molecules at this temperature).^ That energy is the same thing as temperature.
  • Astronomy Cast - Questions Show: Hidden Fusion, the Speed of Neutrinos, and Hawking Radiation 14 January 2010 20:24 UTC www.astronomycast.com [Source type: General]

^ At the same time it does have energy.
  • Astronomy Cast - Questions Show: Hidden Fusion, the Speed of Neutrinos, and Hawking Radiation 14 January 2010 20:24 UTC www.astronomycast.com [Source type: General]

^ Sounds that vibrate many times per second are called "high-frequency" sounds, and those which vibrate less frequently are known as "low-frequency" sounds.
  • Some Basic Principles 14 January 2010 20:24 UTC harada-sound.com [Source type: FILTERED WITH BAYES]

.For air, these conditions are fulfilled at room temperature, and also temperatures considerably below room temperature (see tables below).^ This approach moves to lower temperatures at higher pressures, seemingly absent at ~200 MPa [ 561 ] (see below, D5 ).
  • Explanation of the Density Anomalies of Water (D1-D19) 14 January 2010 20:24 UTC www.lsbu.ac.uk [Source type: Academic]

^ Consequently, in the demonstrations described here, the sound intensity should always be kept at a level well below the threshold of pain (see Table 3.1).
  • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

See the section on gases in specific heat capacity for a more complete discussion of this phenomenon.
For air, we use a simplified symbol \ R_* = R/M_{\mathrm{air}}.
.Additionally, if temperatures in degrees Celsius(°C) are to be used to calculate air speed in the region near 273 kelvins, then Celsius temperature \vartheta = T - 273.15 may be used.^ The speed of sound in air depends on temperature but is near 340 m/s.
  • AAAS2001 14 January 2010 20:24 UTC www.exo.net [Source type: General]

^ Temperature will affect the speed of sound-- in air, the speed of sound increases approximately .60 m/s for each degree Celsius: .
  • Some Basic Principles 14 January 2010 20:24 UTC harada-sound.com [Source type: FILTERED WITH BAYES]

^ The calculator determines the speed of sound using the empirical formula developed by Chen and Millero in their 1977 publication "Speed of Sound in Seawater at High Pressures."
  • The NSDL Scout Report for Physical Sciences -- Volume 1, Number 24 23 September 2009 2:36 UTC scout.wisc.edu [Source type: FILTERED WITH BAYES]

Then:
c_{\mathrm{ideal}} = \sqrt{\gamma \cdot R_* \cdot T} = \sqrt{\gamma \cdot R_* \cdot (\vartheta + 273.15\;^{\circ}\mathrm{C})}
c_{\mathrm{ideal}} = \sqrt{\gamma \cdot R_* \cdot 273.15} \cdot \sqrt{1+\frac{\vartheta}{273.15\;^{\circ}\mathrm{C}}}
.For dry air, where \vartheta\, (theta) is the temperature in degrees Celsius(°C).^ In dry air with a temperature of 21 °C (70 °F) the speed of sound is 344 m/s (1230 km/h, or 770 mph, or 1130 ft/s).
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ Temperature will affect the speed of sound-- in air, the speed of sound increases approximately .60 m/s for each degree Celsius: .
  • Some Basic Principles 14 January 2010 20:24 UTC harada-sound.com [Source type: FILTERED WITH BAYES]

Making the following numerical substitutions: \ R = 8.314510 \cdot \mathrm{J \cdot mol^{-1}} \cdot K^{-1} is the molar gas constant in J/mole/Kelvin; \ M_{\mathrm{air}} = 0.0289645 \cdot \mathrm{kg \cdot mol^{-1}} is the mean molar mass of air, in kg; and using the ideal diatomic gas value of \ \gamma\, = 1.4000
Then:
c_{\mathrm{air}} = 331.3 \ \mathrm{m \cdot s^{-1}} \sqrt{1+\frac{\vartheta^{\circ}\mathrm{C}}{273.15\;^{\circ}\mathrm{C}}}
Using the first two terms of the Taylor expansion:
 c_{\mathrm{air}} = 331.3 \ \mathrm{m \cdot s^{-1}} (1 + \frac{\vartheta^{\circ}\mathrm{C}}{2 \cdot 273.15\;^{\circ}\mathrm{C}}) \,
 c_{\mathrm{air}} = ( 331{.}3 + 0{.}606\;^{\circ}\mathrm{C}^{-1} \cdot \vartheta)\ \mathrm{ m \cdot s^{-1}}\,
The derivation includes the two approximate equations which were given in the introduction.

Effects due to wind shear

.The speed of sound varies with temperature.^ The speed of the sound wave varies with the temperature.

^ Increasing the pressure increases the speed of sound and shifts the maximum to higher temperatures, both in line with the effect on the density.
  • Explanation of the Density Anomalies of Water (D1-D19) 14 January 2010 20:24 UTC www.lsbu.ac.uk [Source type: Academic]

^ Foot petals control motors for sound speed and variable speed viewing.

.Since temperature and sound velocity normally decrease with increasing altitude, sound is refracted upward, away from listeners on the ground, creating an acoustic shadow at some distance from the source.^ Since temperature and thus the speed of sound normally decrease with increasing altitude, sound is refracted upward, away from listeners on the ground, creating an acoustic shadow at some distance from the source.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ Humidity also has a small, but measurable effect on sound speed (increase of about 0.1%-0.6%), because some oxygen and nitrogen molecules of the air are replaced by the lighter molecules of water.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ Maximum intensity is directly beneath the aircraft, and decreases as the lateral distance from the flight path increases until it ceases to exist because the shock waves refract away from the ground.
  • The speed of sound - sonic boom (sound barrier) facts and pictures 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

[6] .Wind shear of 4 m·s−1·km−1 can produce refraction equal to a typical temperature lapse rate of 7.5 °C/km.^ Higher density produces higher refractive index such that the refractive index temperature maximum lies close to the density maximum, with the small difference due to the slightly different effect of temperature on the specific refractions of ES and CS .
  • Explanation of the Density Anomalies of Water (D1-D19) 14 January 2010 20:24 UTC www.lsbu.ac.uk [Source type: Academic]

[7] .Higher values of wind gradient will refract sound downward toward the surface in the downwind direction,[8] eliminating the acoustic shadow on the downwind side.^ I 0 is the sound intensity at the surface and atten(p) describes the attenuation due to geometric spreading and absorption along the acoustic path, p .
  • Using Ambient Sound to Passively Monitor Sea Surface Processes 14 January 2010 20:24 UTC staff.washington.edu [Source type: Academic]

^ If the sound source is uniform at the surface and absorption and refraction are neglected, the measurement should be independent of depth.
  • Using Ambient Sound to Passively Monitor Sea Surface Processes 14 January 2010 20:24 UTC staff.washington.edu [Source type: Academic]

^ Many performance halls have been found unsatisfactory on acoustic grounds, from unwanted resonances or focussing, improper reverberation time, and badly directed sound.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

This will increase the audibility of sounds downwind. .This downwind refraction effect occurs because there is a wind gradient; the sound is not being carried along by the wind.^ If a wind is blowing, but the source and observer are stationary, then there is no change in frequency of the observed sound.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ Gives you control over the sound, allowing you, for example, to use the same effect over again without it's being recognizable, or to lower the pitch of the sound to fit the situation.

^ In fact, a constant wind will have very little effect on the propagation of sound, not even affecting the frequency heard in different directions.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

[9]
For sound propagation, the exponential variation of wind speed with height can be defined as follows:[10]
\ U(h) = U(0) h ^ \zeta
\ \frac {dU} {dH} = \zeta \frac {U(h)} {h}
where:
 \ U(h) = speed of the wind at height  \ h, and  \ U(0) is a constant
 \ \zeta = exponential coefficient based on ground surface roughness, typically between 0.08 and 0.52
 \ \frac {dU} {dH} = expected wind gradient at height h
.In the 1862 American Civil War Battle of Iuka, an acoustic shadow, believed to have been enhanced by a northeast wind, kept two divisions of Union soldiers out of the battle,[11] because they could not hear the sounds of battle only six miles downwind.^ They could see because they were not blind.
  • speed of dark 14 January 2010 20:24 UTC www.freakface.com [Source type: Original source]

^ At a constant temperature, the ideal gas pressure has no effect on the speed of sound, because pressure and density (also proportional to pressure) have equal but opposite effects on the speed of sound, and the two contributions cancel out exactly.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ The only reason earlier mathematical models failed was because they assumed that all the matter was what we could directly detect/see.
  • DailyTech - German Scientists Declare Speed of Light Broken 14 January 2010 20:24 UTC www.dailytech.com [Source type: General]

[12]

Tables

.
  • T0 is 273.15 K (= 0 °C = 32 °F), giving a theoretical value of 331.3 m·s−1 (= 1086.9 ft/s = 1193 km·h−1 = 741.1 mph = 644.0 knots).^ The table gives values of attenuation in dB km −1 for a temperature of 20°C and a pressure of 101.325 kPa.
    • The speed and attenuation of sound 2.4.1 14 January 2010 20:24 UTC www.kayelaby.npl.co.uk [Source type: Academic]

    Values ranging from 331.3-331.6 may be found in reference literature, however.
  • T20 is 293.15 K (= 20 °C = 68 °F), giving a value of 343.2 m·s−1 (= 1126.0 ft/s = 1236 km·h−1 = 767.8 mph = 667.2 knots).
  • T25 is 298.15 K (= 25 °C = 77 °F), giving a value of 346.1 m·s−1 (= 1135.6 ft/s = 1246 km·h−1 = 774.3 mph = 672.8 knots).
.In fact, assuming an ideal gas, the speed of sound c depends on temperature only, not on the pressure or density (since these change in lockstep for a given temperature and cancel out).^ The speed of sound in a gas is proportional to the square root of its density.
  • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

^ The speed of sound v in a pure gas is related to the pressure p and the density of the gas by: .

^ What are the pressure, density and temperature variations in the wave?
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

Air is almost an ideal gas. .The temperature of the air varies with altitude, giving the following variations in the speed of sound using the standard atmosphere - actual conditions may vary.^ The speed of sound The speed of sound in air is primarily a function of the temperature of the air.
  • AN ANALYSIS OF RECORDED SOUNDS RELATING TO THE ASSASSINATION OF PRESIDENT JOHN F. KENNEDY 14 January 2010 20:24 UTC mcadams.posc.mu.edu [Source type: FILTERED WITH BAYES]

^ The speed of the sound wave varies with the temperature.

^ For helium the speed is 2.7 times the speed of sound in air.
  • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

Effect of temperature
Temperature Speed of sound Density of air Acoustic impedance
\vartheta in °C c in m·s−1 ρ in kg·m−3 Z in N·s·m−3
−25 315.8 1.423 449.4
−20 318.9 1.395 444.9
−15 322.1 1.368 440.6
−10 325.2 1.342 436.1
 −5 328.3 1.317 432.0
  0 331.3 1.292 428.4
 +5 334.3 1.269 424.3
+10 337.3 1.247 420.6
+15 340.3 1.225 416.8
+20 343.2 1.204 413.2
+25 346.1 1.184 409.8
+30 349.0 1.164 406.2
+35 351.9 1.146 403.3
Given normal atmospheric conditions, the temperature, and thus speed of sound, varies with altitude:
Altitude Temperature m·s−1 km·h−1 mph knots
Sea level 15 °C (59 °F) 340 1225 761 661
11 000 m−20 000 m
(Cruising altitude of commercial jets,
and first supersonic flight)
−57 °C (−70 °F) 295 1062 660 573
29 000 m (Flight of X-43A) −48 °C (−53 °F) 301 1083 673 585

Effect of frequency and gas composition

.The medium in which a sound wave is travelling does not always respond adiabatically, and as a result the speed of sound can vary with frequency.^ Dependence on the properties of the medium The speed of sound is variable and depends mainly on the temperature and the properties of the substance through which the wave is traveling.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ The speed of sound is often confused with the frequency of a sound.
  • 03.04.03: Physics of Sound: How We Hear Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: FILTERED WITH BAYES]

^ The speed of sound depends on the type of properties the wave is traveling through.
  • 03.04.03: Physics of Sound: How We Hear Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: FILTERED WITH BAYES]

[13]
.The limitations of the concept of speed of sound due to extreme attenuation are also of concern.^ However, in the stratosphere, the speed of sound increases with height due to heating within the ozone layer, producing a positive sound speed gradient.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ Water has a second sound 'anomaly' (called 'fast sound') concerning the speed of sound.
  • Explanation of the Density Anomalies of Water (D1-D19) 14 January 2010 20:24 UTC www.lsbu.ac.uk [Source type: Academic]

^ Furthermore, perhaps velocity c is limited due to electromagnetic principles, much like the speed of sound is related to air.
  • Damn Interesting • Prepare for Ludicrous Speed 14 January 2010 20:24 UTC www.damninteresting.com [Source type: Original source]

.The attenuation which exists at sea level for high frequencies applies to successively lower frequencies as atmospheric pressure decreases, or as the mean free path increases.^ Higher density means higher pressure, and lower density lower pressure.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ Maximum intensity is directly beneath the aircraft, and decreases as the lateral distance from the flight path increases until it ceases to exist because the shock waves refract away from the ground.
  • The speed of sound - sonic boom (sound barrier) facts and pictures 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ (The atmospheric model for the speed of sound at sea level is 761.18 mph (661.32 knots) - This speed is referred to as MACH 1) .
  • The speed of sound - sonic boom (sound barrier) facts and pictures 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

.For this reason, the concept of speed of sound (except for frequencies approaching zero) progressively loses its range of applicability at high altitudes.:[5] The standard equations for the speed of sound apply with reasonable accuracy only to situations in which the wavelength of the soundwave is considerably longer than the mean free path of molecules in a gas.^ The equation for the speed of sound is speed = distance/time.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

^ The sound propagation should cease when the mean free path for air molecules becomes longer than a few centimeters.
  • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

^ The speed of sound is often confused with the frequency of a sound.
  • 03.04.03: Physics of Sound: How We Hear Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: FILTERED WITH BAYES]

.The molecular composition of the gas contributes both as the mass (M) of the molecules, and their heat capacities, and so both have an influence on speed of sound.^ However, in the stratosphere, the speed of sound increases with height due to heating within the ozone layer, producing a positive sound speed gradient.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ Humidity also has a small, but measurable effect on sound speed (increase of about 0.1%-0.6%), because some oxygen and nitrogen molecules of the air are replaced by the lighter molecules of water.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ At a constant temperature, the ideal gas pressure has no effect on the speed of sound, because pressure and density (also proportional to pressure) have equal but opposite effects on the speed of sound, and the two contributions cancel out exactly.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

.In general, at the same molecular mass, monatomic gases have slightly higher sound speeds (over 9% higher) because they have a higher γ (5/3 = 1.66...^ In general, solids will have a higher speed of sound than liquids, and liquids will have a higher speed of sound than gases.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ Humidity also has a small, but measurable effect on sound speed (increase of about 0.1%-0.6%), because some oxygen and nitrogen molecules of the air are replaced by the lighter molecules of water.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ For example, in low molecular weight gases, such as helium, sound propagates faster compared to heavier gases, such as xenon.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

) than diatomics do (7/5 = 1.4). Thus, at the same molecular mass, the sound speed of a monatomic gas goes up by a factor of
{ c_{\mathrm{gas: monatomic}} \over c_{\mathrm{gas: diatomic}} } = \sqrt{{{{5 / 3} \over {7 / 5}}}} = \sqrt{25 \over 21} = 1.091...
This gives the 9 % difference, and would be a typical ratio for sound speeds at room temperature in helium vs. deuterium, each with a molecular weight of 4. Sound travels faster in helium than deuterium because adiabatic compression heats helium more, since the helium molecules can store heat energy from compression only in translation, but not rotation. .Thus helium molecules (monatomic molecules) travel faster in a sound wave and transmit sound faster.^ All other things being equal, sound will travel more slowly in denser materials, and faster in stiffer ones.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ For example, in low molecular weight gases, such as helium, sound propagates faster compared to heavier gases, such as xenon.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ Sound is a vibration that travels through an elastic medium as a wave.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

.(Sound generally travels at about 70% of the mean molecular speed in gases).^ Speed of sound in gases and vapours .
  • The speed and attenuation of sound 2.4.1 14 January 2010 20:24 UTC www.kayelaby.npl.co.uk [Source type: Academic]

^ In general, solids will have a higher speed of sound than liquids, and liquids will have a higher speed of sound than gases.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ Sound travels a mile in about 5 seconds.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

.Note that in this example we have assumed that temperature is low enough that heat capacities are not influenced by molecular vibration (see heat capacity).^ For example, in low molecular weight gases, such as helium, sound propagates faster compared to heavier gases, such as xenon.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ One interesting effect is that the temperature changes in the adiabatic processes may equilibrate with molecular internal degrees of freedom at low frequencies, while at higher frequencies equilibration does not occur.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ For example thunder is caused when lightning heats the air, causing the air to vibrate.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

.However, vibrational modes simply cause gammas which decrease toward 1, since vibration modes in a polyatomic gas gives the gas additional ways to store heat which do not affect temperature, and thus do not affect molecular velocity and sound velocity.^ Since temperature and thus the speed of sound normally decrease with increasing altitude, sound is refracted upward, away from listeners on the ground, creating an acoustic shadow at some distance from the source.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ The beating of two identical organ pipes can be used to illustrate the variation of the velocity of sound with temperature[1].
  • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

^ To begin we must understand that vibrations cause all sounds.
  • 03.04.03: Physics of Sound: How We Hear Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: FILTERED WITH BAYES]

Thus, the effect of higher temperatures and vibrational heat capacity acts to increase the difference between sound speed in monatomic vs. polyatomic molecules, with the speed remaining greater in monatomics.

Mach number

.Mach number, a useful quantity in aerodynamics, is the ratio of air speed to the local speed of sound.^ Mach number Main article: Mach number Mach number, a useful quantity in aerodynamics, is the ratio of an object's speed to the speed of sound in the medium through which it is passing (again, usually air).
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ For helium the speed is 2.7 times the speed of sound in air.
  • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

^ Humidity also has a small, but measurable effect on sound speed (increase of about 0.1%-0.6%), because some oxygen and nitrogen molecules of the air are replaced by the lighter molecules of water.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

.At altitude, for reasons explained, Mach number is a function of temperature.^ At altitude, for reasons explained, Mach number is a function of temperature.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ Aircraft flight instruments, however, operate using pressure differential to compute Mach number; not temperature.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ One reason for this is that the temperature of the atmosphere decreases rapidly with altitude (roughly 6 °C for each 1000 m).
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

.Aircraft flight instruments, however, operate using pressure differential to compute Mach number; not temperature.^ Aircraft flight instruments, however, operate using pressure differential to compute Mach number; not temperature.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ Aircraft flight instruments need to operate this way because the impact pressure sensed by a Pitot tube is dependent on altitude as well as speed.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ Mach number Main article: Mach number Mach number, a useful quantity in aerodynamics, is the ratio of an object's speed to the speed of sound in the medium through which it is passing (again, usually air).
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

.The assumption is that a particular pressure represents a particular altitude and, therefore, a standard temperature.^ The assumption is that a particular pressure represents a particular altitude and, therefore, a standard temperature.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

.Aircraft flight instruments need to operate this way because the stagnation pressure sensed by a Pitot tube is dependent on altitude as well as speed.^ Aircraft flight instruments need to operate this way because the impact pressure sensed by a Pitot tube is dependent on altitude as well as speed.
  • The speed of sound facts pictures and information | Mach 1 = 761.18 mph 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

^ As the moon acquires more energy from Earth's spin it does not actually speed up, instead it slows down because it orbits at a higher altitude (R' increases).

^ They are usually of similar strength and the time interval between the two as they reach the ground is primarily dependent on the size of the aircraft and its altitude.
  • The speed of sound - sonic boom (sound barrier) facts and pictures 14 January 2010 20:24 UTC www.aviationexplorer.com [Source type: FILTERED WITH BAYES]

Assuming air to be an ideal gas, the formula to compute Mach number in a subsonic compressible flow is derived from Bernoulli's equation for M<1:[14]
{M}=\sqrt{5\left[\left(\frac{q_c}{P}+1\right)^\frac{2}{7}-1\right]}
where
M is Mach number
qc is dynamic pressure and
P is static pressure.
The formula to compute Mach number in a supersonic compressible flow is derived from the Rayleigh Supersonic Pitot equation:
{M}=0.88128485\sqrt{\left[\left(\frac{q_c}{P}+1\right)\left(1-\frac{1}{[7M^2]}\right)^{2.5}\right]}
where
M is Mach number
qc is dynamic pressure measured behind a normal shock
P is static pressure.
As can be seen, M appears on both sides of the equation. .The easiest method to solve the supersonic M calculation is to enter both the subsonic and supersonic equations into a computer spreadsheet such as Microsoft Excel, OpenOffice.org Calc, or some equivalent program.^ Most astronomers calculate the length of the lunar orbit manually by the following equivalent circle method: .

^ Such a method was provided by a computation of the binary correlation coefficient of the two sequences.
  • AN ANALYSIS OF RECORDED SOUNDS RELATING TO THE ASSASSINATION OF PRESIDENT JOHN F. KENNEDY 14 January 2010 20:24 UTC mcadams.posc.mu.edu [Source type: FILTERED WITH BAYES]

^ For with this method of calculation, Planck introduced into physics the quantum hypothesis, which has since received brilliant confirmation.
  • Speed of Gravity / Speed of Light 14 January 2010 20:24 UTC www.spaceandmotion.com [Source type: FILTERED WITH BAYES]

.First determine if M is indeed greater than 1.0 by calculating M from the subsonic equation.^ It’s not that air forms a wall of any sort—a “sound barrier”—though it is indeed compressed to a greater density than the ambient atmosphere.
  • Mach 1: Assaulting the Barrier | History of Flight | Air & Space Magazine 14 January 2010 20:24 UTC www.airspacemag.com [Source type: FILTERED WITH BAYES]

.If M is greater than 1.0 at that point, then use the value of M from the subsonic equation as the initial condition in the supersonic equation.^ From masher2's point of view, however, it would be slightly longer, because the train is moving, and so the light must travel a distance that is slightly greater than 2h (say 2h+e).
  • DailyTech - German Scientists Declare Speed of Light Broken 14 January 2010 20:24 UTC www.dailytech.com [Source type: General]

^ Internegative - An intermediate copy of a film, made on a very fine-grained stock, and used to make a greater number of prints than it is practical to make from the A&B Rolls.

.Then perform a simple iteration of the supersonic equation, each time using the last computed value of M, until M converges to a value—usually in just a few iterations.^ Just before leaving, he decided to go and catch the last few mins of the show.

^ Last time I uses Safari, it wouldn’t load images when I pressed the back button.
  • Speed of dialouge in tv shows « GraphJam: Music and Pop Culture in Charts and Graphs. Let us explain them. 14 January 2010 20:24 UTC graphjam.com [Source type: FILTERED WITH BAYES]

^ By using a simple computer programme various straight lines were checked for their best fit.
  • Reports of the Death of Speed of Light Decay are Premature 14 January 2010 20:24 UTC www.ldolphin.org [Source type: FILTERED WITH BAYES]

[14]

Experimental methods

.A range of different methods exist for the measurement of sound in air.^ How could you measure a sound system's response if it did not already exist?
  • Measurement and Characterization of Sound Systems Sound System Characterization and Measurement 14 January 2010 20:24 UTC digitalcontentproducer.com [Source type: FILTERED WITH BAYES]

^ Students will conduct hands-on experiments that will explore the different measures of sound as one of their five senses.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

^ The measurement of the speed of sound took a step back in 1709, when Newton developed the first predictive formula for sound transmission in error (I mean, in air .
  • Measurement and Characterization of Sound Systems Sound System Characterization and Measurement 14 January 2010 20:24 UTC digitalcontentproducer.com [Source type: FILTERED WITH BAYES]

.The earliest, reasonably accurate estimate of the speed of sound in air was made by William Derham, and acknowledged by Isaac Newton.^ Speed of sound in air .
  • The speed and attenuation of sound 2.4.1 14 January 2010 20:24 UTC www.kayelaby.npl.co.uk [Source type: Academic]

^ When a sound is made such as a bell or a hand clapping, the vibrations from the sound bounce off surrounding particles such as air.
  • 03.04.03: Physics of Sound: How We Hear Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: FILTERED WITH BAYES]

^ The current age holds that sound is transmitted as a wave of pressure variations through the medium of air at a speed of approximately 1,130 fps (time).
  • Measurement and Characterization of Sound Systems Sound System Characterization and Measurement 14 January 2010 20:24 UTC digitalcontentproducer.com [Source type: FILTERED WITH BAYES]

Derham had a telescope at the top of the tower of the Church of St Laurence in Upminster, England. .On a calm day, a synchronized pocket watch would be given to an assistant who would fire a shotgun at a pre-determined time from a conspicuous point some miles away, across the countryside.^ I would any day choose the Pre over the iPhone 3GS. Something new to toy around with.
  • Say Hello To The iPhone 3G S — “S” Is For Speed 14 January 2010 20:24 UTC www.techcrunch.com [Source type: General]

^ This is because time would be slowed down in your frame of reference by half, compared to the observer who is “standing still” and watching you pass.
  • Damn Interesting • Prepare for Ludicrous Speed 14 January 2010 20:24 UTC www.damninteresting.com [Source type: Original source]

^ Some students are "tortoises" who realize that speed without clean notes is totally worthless, and that the shortest route between two points is a straight line.
  • The Court Reporting Students' Online Support Center 14 January 2010 20:24 UTC www.his.com [Source type: General]

This could be confirmed by telescope. .He then measured the interval between seeing gunsmoke and arrival of the noise using an half-second pendulum.^ The relationship between sound intensity and perceived sound is measured logarithmically (which is a method used to scale a large range of values), using a unit called the decibel or db.
  • JISC Digital Media - Audio: The Physical Principles of Sound 14 January 2010 20:24 UTC www.jiscdigitalmedia.ac.uk [Source type: FILTERED WITH BAYES]

^ When the crude methods of prediction and measurement employed in the past are viewed through the eyes of the present, one can see a huge gap between the predicted response and that which would be measured.
  • Measurement and Characterization of Sound Systems Sound System Characterization and Measurement 14 January 2010 20:24 UTC digitalcontentproducer.com [Source type: FILTERED WITH BAYES]

^ Because we knew that the range of the correction was 1.03 to 1.07, theoretically we could use any value between 1.03 and 1.07 to adjust the measured time intervals between the impulses on the DPD recording.
  • AN ANALYSIS OF RECORDED SOUNDS RELATING TO THE ASSASSINATION OF PRESIDENT JOHN F. KENNEDY 14 January 2010 20:24 UTC mcadams.posc.mu.edu [Source type: FILTERED WITH BAYES]

.The distance from where the gun was fired was found by triangulation, and simple division (time / distance) provided velocity.^ The muzzle blast travel time is obtained by dividing the distance between the gun and the microphone in Dealey Plaza (213 feet) by the speed of sound.
  • AN ANALYSIS OF RECORDED SOUNDS RELATING TO THE ASSASSINATION OF PRESIDENT JOHN F. KENNEDY 14 January 2010 20:24 UTC mcadams.posc.mu.edu [Source type: FILTERED WITH BAYES]

^ Similarly, assuming a fixed location of the gun, any change in the location of the listener will change the distances between him and the echo-producing structures, and thus the timing of the pattern of sounds he hears.
  • AN ANALYSIS OF RECORDED SOUNDS RELATING TO THE ASSASSINATION OF PRESIDENT JOHN F. KENNEDY 14 January 2010 20:24 UTC mcadams.posc.mu.edu [Source type: FILTERED WITH BAYES]

^ The time taken for the muzzle blast echoes to be heard also depends on the speed of sound and on the total distance each echo must travel, which is the total of the distance from the gun to the echo-producing object and then to the listener.
  • AN ANALYSIS OF RECORDED SOUNDS RELATING TO THE ASSASSINATION OF PRESIDENT JOHN F. KENNEDY 14 January 2010 20:24 UTC mcadams.posc.mu.edu [Source type: FILTERED WITH BAYES]

.Lastly, by making many observations, using a range of different distances, the inaccuracy of the half-second pendulum could be averaged out, giving his final estimate of the speed of sound.^ The equation for the speed of sound is speed = distance/time.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

^ At 0 °C the speed of sound in distilled water is 1482 m/s, in sea water of 3.5% salinity 1522 m/s, in mercury 1450 m/s, in steel rails 5050 m/s, and in bulk soft iron 5957 m/s, which should give some idea of the range of phase velocities.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ The total distance of the echo path divided by the speed of sound was the echo travel time.
  • AN ANALYSIS OF RECORDED SOUNDS RELATING TO THE ASSASSINATION OF PRESIDENT JOHN F. KENNEDY 14 January 2010 20:24 UTC mcadams.posc.mu.edu [Source type: FILTERED WITH BAYES]

Modern stopwatches enable this method to be used today over distances as short as 200 - 400 metres, and not needing something as loud as a shotgun.

Single-shot timing methods

.The simplest concept is the measurement made using two microphones and a fast recording device such as a digital storage scope.^ The delay times of the impulse sounds on the DPD recording were measured directly from a graph of the sequence of impulse waveforms, such as the one shown in figure 3.
  • AN ANALYSIS OF RECORDED SOUNDS RELATING TO THE ASSASSINATION OF PRESIDENT JOHN F. KENNEDY 14 January 2010 20:24 UTC mcadams.posc.mu.edu [Source type: FILTERED WITH BAYES]

^ It is best to find the proper frequency beforehand using a digital frequency meter and to record the value (to a precision of at least one Hertz).
  • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

^ Can either of you use a digital output of the CD and record tracks back to PC for analysis?
  • CDR Burn Speed and Audio Quality 14 January 2010 20:24 UTC forums.afterdawn.com [Source type: General]

This method uses the following idea.
If a sound source and two microphones are arranged in a straight line, with the sound source at one end, then the following can be measured:
.1. The distance between the microphones (x), called microphone basis.^ The muzzle blast travel time is obtained by dividing the distance between the gun and the microphone in Dealey Plaza (213 feet) by the speed of sound.
  • AN ANALYSIS OF RECORDED SOUNDS RELATING TO THE ASSASSINATION OF PRESIDENT JOHN F. KENNEDY 14 January 2010 20:24 UTC mcadams.posc.mu.edu [Source type: FILTERED WITH BAYES]

2. The time of arrival between the signals (delay) reaching the different microphones (t)
Then v = x / t

Other methods

.In these methods the time measurement has been replaced by a measurement of the inverse of time (frequency).^ Each of these affected either the results of the analysis or the method by which the required echo-delay time sequences were obtained.
  • AN ANALYSIS OF RECORDED SOUNDS RELATING TO THE ASSASSINATION OF PRESIDENT JOHN F. KENNEDY 14 January 2010 20:24 UTC mcadams.posc.mu.edu [Source type: FILTERED WITH BAYES]

.Kundt's tube is an example of an experiment which can be used to measure the speed of sound in a small volume.^ The relationship between sound intensity and perceived sound is measured logarithmically (which is a method used to scale a large range of values), using a unit called the decibel or db.
  • JISC Digital Media - Audio: The Physical Principles of Sound 14 January 2010 20:24 UTC www.jiscdigitalmedia.ac.uk [Source type: FILTERED WITH BAYES]

^ II. Sound Production III. Sound Waves IV. Speed of Sound V. Echoes Each of the topics covered in this unit will be explored through hands-on experiments and demonstrations.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

^ The decibel is a unit used in consumer and professional audio equipment, be it hi-hi amps or mixing desks, as it allows us to apply a standard measurement for the volume of sounds we listen to.
  • JISC Digital Media - Audio: The Physical Principles of Sound 14 January 2010 20:24 UTC www.jiscdigitalmedia.ac.uk [Source type: FILTERED WITH BAYES]

.It has the advantage of being able to measure the speed of sound in any gas.^ The speed of sound in a gas is proportional to the square root of its density.
  • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

^ The “sound barrier” speed is created by the density of the atmosphere being travelled through.
  • Damn Interesting • Prepare for Ludicrous Speed 14 January 2010 20:24 UTC www.damninteresting.com [Source type: Original source]

^ The theoretical value of sound speed matched the measured with the critical insertions of temperature and transmission medium.
  • Measurement and Characterization of Sound Systems Sound System Characterization and Measurement 14 January 2010 20:24 UTC digitalcontentproducer.com [Source type: FILTERED WITH BAYES]

This method uses a powder to make the nodes and antinodes visible to the human eye. This is an example of a compact experimental setup.
.A tuning fork can be held near the mouth of a long pipe which is dipping into a barrel of water.^ He then stretched smaller wires until they matched the tuning of an organ pipe and scaled up the numbers from the long wire and correctly calculated its frequency.
  • Measurement and Characterization of Sound Systems Sound System Characterization and Measurement 14 January 2010 20:24 UTC digitalcontentproducer.com [Source type: FILTERED WITH BAYES]

^ Sine waves can be produced with tuning forks or organ pipes or with an electronic function generator.
  • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

^ The bottom can be cut out of a Coke bottle, and different notes played by blowing over the top while it is dipped different depths into a beaker of water.
  • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

.In this system it is the case that the pipe can be brought to resonance if the length of the air column in the pipe is equal to ({1+2n}λ/4) where n is an integer.^ A resonance will occur in the pipe when the length of the pipe is an odd multiple of a quarter wavelength.
  • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

.As the antinodal point for the pipe at the open end is slightly outside the mouth of the pipe it is best to find two or more points of resonance and then measure half a wavelength between these.^ Take a piece of paper and roll it into a cone, with the small end a half- inch opening or larger.
  • 03.04.03: Physics of Sound: How We Hear Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: FILTERED WITH BAYES]

^ If the frequencies/Shapes correctly match, then these two resonators can 'resonantly couple' like two tuning forks and exchange vibrational energy.
  • Speed of Gravity / Speed of Light 14 January 2010 20:24 UTC www.spaceandmotion.com [Source type: FILTERED WITH BAYES]

^ Similarly, two identical organ pipes can be used if one is detuned by partially covering its mouth or by adjusting a movable plug if the pipe is so equipped.
  • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

Here it is the case that v =

Non-gaseous media

Speed of sound in solids

In a solid, there is a non-zero stiffness both for volumetric and shear deformations. .Hence, it is possible to generate sound waves with different velocities dependent on the deformation mode.^ Another reason for carrying the stroke as far through the sound as possible is that it may prevent conflicts which exist in a spelling-dependent theory--and conflicts are the nightmare of the realtime writer.
  • The Court Reporting Students' Online Support Center 14 January 2010 20:24 UTC www.his.com [Source type: General]

^ Under the conditions we have assumed, sound waves travel without dispersion at the phase velocity c = sqrt(γp 0 /ρ 0 ), and obey the principle of superposition.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ Hence the difference between "special" relativity and general relativity.
  • DailyTech - German Scientists Declare Speed of Light Broken 14 January 2010 20:24 UTC www.dailytech.com [Source type: General]

.Sound waves generating volumetric deformations (compressions) and shear deformations are called longitudinal waves and shear waves, respectively.^ The manner in which an acoustic wave is propagated, as characterized by the particle motion in the wave (shear, Lamb, surface or longitudinal).RW .
  • JISC Digital Media - Audio: The Physical Principles of Sound 14 January 2010 20:24 UTC www.jiscdigitalmedia.ac.uk [Source type: FILTERED WITH BAYES]

^ A tuning fork propagates sound waves longitudinally.
  • JISC Digital Media - Audio: The Physical Principles of Sound 14 January 2010 20:24 UTC www.jiscdigitalmedia.ac.uk [Source type: FILTERED WITH BAYES]

^ Although similar in shape to a sine wave, the diagram represents the displacement from equilibrium over time creating a longitudinal sound wave.
  • JISC Digital Media - Audio: The Physical Principles of Sound 14 January 2010 20:24 UTC www.jiscdigitalmedia.ac.uk [Source type: FILTERED WITH BAYES]

In earthquakes, the corresponding seismic waves are called P-waves and S-waves, respectively. The sound velocities of these two type waves are respectively given by[15]:
 c_{\mathrm{l}} = \sqrt {\frac{K+\frac{4}{3}G}{\rho}} = \sqrt {\frac{E (1-
u)}{\rho (1+
u)(1 - 2 
u)}}
 c_{\mathrm{s}} = \sqrt {\frac{G}{\rho}},
where K and G are the bulk modulus and shear modulus of the elastic materials, respectively. .Note that the speed of longitudinal/compression waves depends both on the compression and shear resistance properties of the material, while the speed of shear waves depends on the shear properties only.^ The speed of any wave depends upon the properties of the medium through which the wave is traveling.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

^ The speed of sound depends on the type of properties the wave is traveling through.
  • 03.04.03: Physics of Sound: How We Hear Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: FILTERED WITH BAYES]

^ Only gravitational waves (changes in gravitational potential) propagate at light speed.
  • Meaning of the "speed of gravity" 14 January 2010 20:24 UTC www.metaresearch.org [Source type: Original source]

.Typically, compression or P-waves travel faster in materials than do shear waves, and in earthquakes this is the reason that onset of an earthquake is often preceded by a quick upward-downward shock, before arrival of waves that produce a side-to-side motion.^ A sound wave will travel faster in a less dense material rather than in a more dense material.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

^ After we have observed how waves travel, we will go out side to experiment with this concept.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

^ I’m just waiting to see what happens to the materials the craft is made of and the people in side it when there subjected to the G-forces of faster than light travel.
  • Damn Interesting • Prepare for Ludicrous Speed 14 January 2010 20:24 UTC www.damninteresting.com [Source type: Original source]

.E is the Young's modulus, and ν is Poisson's ratio.^ The velocity of shear waves in an extensive medium is c S = √( Gρ ) = √{ E /2 ρ (1 + σ )}, E being Young’s modulus, G the rigidity modulus and σ Poisson’s ratio, and this is also the velocity of torsional waves in thin cylindrical bars.
  • The speed and attenuation of sound 2.4.1 14 January 2010 20:24 UTC www.kayelaby.npl.co.uk [Source type: Academic]


For example, for a typical steel alloy, K = 170 GPa, G = 80 GPa and ρ = 7700 kg/m3, yielding a longitudinal velocity cl of 6000 m/s.[15] .This is in reasonable agreement with cl=5930 m/s measured experimentally for a (possibly different) type of steel.^ I am mearly suggesting a possibly scenario for experimentation and the rough logistics of launching a vehicle of this type and how it is immensly different from anything else to date.
  • Damn Interesting • Prepare for Ludicrous Speed 14 January 2010 20:24 UTC www.damninteresting.com [Source type: Original source]

[16]
The shear velocity cs is estimated at 3200 m/s using the same numbers.

Speed of sound in liquids

.In a fluid the only non-zero stiffness is to volumetric deformation (a fluid does not sustain shear forces).^ What only one of us seems to appreciate is that gravitational force does not have the general property of Lorentz invariance, whatever its aesthetic appeal.
  • Meaning of the "speed of gravity" 14 January 2010 20:24 UTC www.metaresearch.org [Source type: Original source]

^ Bulk longitudinal waves in solids are a little faster than longitudinal waves in fluids, because of the additional shear forces.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

Hence the speed of sound in a fluid is given by
 c_{\mathrm{fluid}} = \sqrt {\frac{K}{\rho}}
where
K is the bulk modulus of the fluid

Water

.The speed of sound in water is of interest to anyone using underwater sound as a tool, whether in a laboratory, a lake or the ocean.^ It's audio master technilogy aims at minimizing the error rate by using 1) low write speeds 2) increasing the length of pits and gaps (by using a slightly higher rotation speed) That sounds interesting.
  • CDR Burn Speed and Audio Quality 14 January 2010 20:24 UTC forums.afterdawn.com [Source type: General]

^ He has spent more than 20 years aligning sound systems using high-resolution acoustic measurement tools.
  • Measurement and Characterization of Sound Systems Sound System Characterization and Measurement 14 January 2010 20:24 UTC digitalcontentproducer.com [Source type: FILTERED WITH BAYES]

^ Crystal Sync - Specifically, a way of recording Sync Sound where the camera runs at correct speed with a quartz crystal-governed motor, and tape recorder records its pilottone using a built-in quartz crystal pilottone generator.

Examples are sonar, acoustic communication and acoustical oceanography. .See Discovery of Sound in the Sea for other examples of the uses of sound in the ocean (by both man and other animals).^ There are several techniques we use to both simplify the sound and reduce the number of strokes.
  • The Court Reporting Students' Online Support Center 14 January 2010 20:24 UTC www.his.com [Source type: General]

^ Nature uses both sea salt and land dust to trigger rain: Wind at the surface of the seas causes waves to roll.

^ The two discoveries, however, do not apply to filmmakers, who are consistently able to produce sound at the speed of light in a vacuum (see Star Wars ).
  • Measurement and Characterization of Sound Systems Sound System Characterization and Measurement 14 January 2010 20:24 UTC digitalcontentproducer.com [Source type: FILTERED WITH BAYES]

.In fresh water, sound travels at about 1497 m/s at 25 °C. See Technical Guides - Speed of Sound in Pure Water for an online calculator.^ The total distance of the echo path divided by the speed of sound was the echo travel time.
  • AN ANALYSIS OF RECORDED SOUNDS RELATING TO THE ASSASSINATION OF PRESIDENT JOHN F. KENNEDY 14 January 2010 20:24 UTC mcadams.posc.mu.edu [Source type: FILTERED WITH BAYES]

^ The speed of sound is about a million times slower than the speed of light.
  • 03.04.03: Physics of Sound: How We Hear Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: FILTERED WITH BAYES]

^ The microphone that picked up the sounds of the probable gunshot was on Elm Street and was moving at a speed of about 11 miles Der hour in the same direction as the motorcade.
  • AN ANALYSIS OF RECORDED SOUNDS RELATING TO THE ASSASSINATION OF PRESIDENT JOHN F. KENNEDY 14 January 2010 20:24 UTC mcadams.posc.mu.edu [Source type: FILTERED WITH BAYES]

Seawater

.
Sound speed as a function of depth at a position north of Hawaii in the Pacific Ocean derived from the 2005 World Ocean Atlas.
^ The speed of sound The speed of sound in air is primarily a function of the temperature of the air.
  • AN ANALYSIS OF RECORDED SOUNDS RELATING TO THE ASSASSINATION OF PRESIDENT JOHN F. KENNEDY 14 January 2010 20:24 UTC mcadams.posc.mu.edu [Source type: FILTERED WITH BAYES]

^ Functions and their derivatives are *not* constrained to have the same properties, such as propagation speed.
  • Meaning of the "speed of gravity" 14 January 2010 20:24 UTC www.metaresearch.org [Source type: Original source]

The SOFAR channel is centered on the minimum in sound speed at ca. 750-m depth.
.In salt water that is free of air bubbles or suspended sediment, sound travels at about 1560 m/s.^ Sound travels a mile in about 5 seconds.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

^ At low pressures, absorption occurs when the wavelength becomes comparable to the molecular mean free path (about 66nm in air at STP).
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ Sound travelling through air is proportional to the square root of the absolute temperature.
  • JISC Digital Media - Audio: The Physical Principles of Sound 14 January 2010 20:24 UTC www.jiscdigitalmedia.ac.uk [Source type: FILTERED WITH BAYES]

.The speed of sound in seawater depends on pressure (hence depth), temperature (a change of 1 °C ~ 4 m/s), and salinity (a change of 1‰ ~ 1 m/s), and empirical equations have been derived to accurately calculate sound speed from these variables.^ The equation for the speed of sound is speed = distance/time.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

^ What are the pressure, density and temperature variations in the wave?
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ The speed of sound is taken as 750 mph in these calculations.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

[17] .Other factors affecting sound speed are minor.^ Elastic properties also affect the speed of sound.
  • 03.04.03: Physics of Sound: How We Hear Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: FILTERED WITH BAYES]

^ In the South Sound, millions of dollars would be spent laying track and other infrastructure needed for high-speed passenger trains.
  • Lakewood questions high-speed train plan | Local News - The News Tribune | Seattle-Tacoma News, Weather, Sports, Jobs, Homes and Cars | South Puget Sound's Destination 14 January 2010 20:24 UTC www.thenewstribune.com [Source type: News]

^ Air pressure is an elastic property that affects the speed of sound.
  • 03.04.03: Physics of Sound: How We Hear Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: FILTERED WITH BAYES]

.For more information see Dushaw et al.^ If I see a presentation that is confusing (or even contains some error), and I have an opportunity to help by presenting more, or other, information, I try to do so.
  • Damn Interesting • Prepare for Ludicrous Speed 14 January 2010 20:24 UTC www.damninteresting.com [Source type: Original source]

[18]
A simple empirical equation for the speed of sound in sea water with reasonable accuracy for the world's oceans is due to Mackenzie:[19]
c(T, S, z) = a1 + a2T + a3T2 + a4T3 + a5(S - 35) + a6z + a7z2 + a8T(S - 35) + a9Tz3
where .T, S, and z are temperature in degrees Celsius, salinity in parts per thousand and depth in metres, respectively.^ To a first order approximation, in this temperature range the speed of sound increases at a rate of 1 foot per second per degree Fahrenheit.
  • AN ANALYSIS OF RECORDED SOUNDS RELATING TO THE ASSASSINATION OF PRESIDENT JOHN F. KENNEDY 14 January 2010 20:24 UTC mcadams.posc.mu.edu [Source type: FILTERED WITH BAYES]

The constants a1, a2, ..., a9 are:
a1 = 1448.96, a2 = 4.591, a3 = -5.304×10-2, a4 = 2.374×10-4, a5 = 1.340,
a6 = 1.630×10-2, a7 = 1.675×10-7, a8 = -1.025×10-2, a9 = -7.139×10-13
with check value 1550.744 m/s for T=25 °C, S=35‰, z=1000 m. This equation has a standard error of 0.070 m/s for salinities between 25 and 40 ppt. .See Technical Guides - Speed of Sound in Sea-Water for an online calculator.^ At 0 °C the speed of sound in distilled water is 1482 m/s, in sea water of 3.5% salinity 1522 m/s, in mercury 1450 m/s, in steel rails 5050 m/s, and in bulk soft iron 5957 m/s, which should give some idea of the range of phase velocities.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ This was a problem that baffled Newton, when the calculated and measured speeds of sound did not agree, and was only settled later by Laplace.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ If light and sound have a measurable speed doesn't that mean that everything we see or hear has already happened?
  • speed of dark 14 January 2010 20:24 UTC www.freakface.com [Source type: Original source]

.Other equations for sound speed in sea water are accurate over a wide range of conditions, but are far more complicated, e.g., that by V. A. Del Grosso[20] and the Chen-Millero-Li Equation.^ The equation for the speed of sound is speed = distance/time.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

^ At 0 °C the speed of sound in distilled water is 1482 m/s, in sea water of 3.5% salinity 1522 m/s, in mercury 1450 m/s, in steel rails 5050 m/s, and in bulk soft iron 5957 m/s, which should give some idea of the range of phase velocities.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ The range of human hearing is usually taken to be about 20 Hz to 20 kHz, although it is more accurate to say that the ear is most sensitive to frequencies around 4000 Hz and becomes progressively less sensitive at higher and lower frequencies requiring greater sound intensity to produce a detectable response.
  • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

[18][21]

Speed in plasma

The speed of sound in a plasma for the common case that the electrons are hotter than the ions (but not too much hotter) is given by the formula (see here)
c_s = (\gamma ZkT_e/m_i)^{1/2} = 9.79	imes10^3\,(\gamma ZT_e/\mu)^{1/2}\,\mbox{m/s}
.In contrast to a gas, the pressure and the density are provided by separate species, the pressure by the electrons and the density by the ions.^ The peculiar sound of one's voice after breathing helium or sulfur hexafluoride provides an amusing demonstration of the variation of the velocity of sound with the density of a gas.
  • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

^ In an ideal gas, the pressure is proportional to the density when the temperature is held constant, so in this case the fractional change in pressure will be equal to the fractional change in density, or the condensation.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ We further restrict ourselves to propagation in a gas, with a density ρ 0 and a pressure p 0 when at rest.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

The two are coupled through a fluctuating electric field.

Gradients

.When sound spreads out evenly in all directions in three dimensions, the intensity drops in proportion to the inverse square of the distance.^ Most sounds spread out in all directions from the source of the sound.
  • AN ANALYSIS OF RECORDED SOUNDS RELATING TO THE ASSASSINATION OF PRESIDENT JOHN F. KENNEDY 14 January 2010 20:24 UTC mcadams.posc.mu.edu [Source type: FILTERED WITH BAYES]

^ Well this is exactly how the universe expands around us: All distances increase however they remain proportional.

^ The speed of sound in a gas is proportional to the square root of its density.
  • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

.However, in the ocean there is a layer called the 'deep sound channel' or SOFAR channel which can confine sound waves at a particular depth.^ The pressure variations in a sound wave are so rapid, however, that there is no time to reach isothermal conditions.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ Soundstage depth wasn’t as deep as very good single-ended amps, but layering was portrayed well.
  • Ray of Sound Audion Reviews 14 January 2010 20:24 UTC www.rayofsound.com [Source type: General]

.In the SOFAR channel, the speed of sound is lower than that in the layers above and below.^ The speed of sound is about a million times slower than the speed of light.
  • 03.04.03: Physics of Sound: How We Hear Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: FILTERED WITH BAYES]

^ Consequently, when the recording is played back at the faster, correct speed, the recorded impulse sounds will be heard closer together than they actually were at the time the recording was made.
  • AN ANALYSIS OF RECORDED SOUNDS RELATING TO THE ASSASSINATION OF PRESIDENT JOHN F. KENNEDY 14 January 2010 20:24 UTC mcadams.posc.mu.edu [Source type: FILTERED WITH BAYES]

^ In 1947, no airplane had ever gone faster than the speed of sound.
  • Mach 1: Assaulting the Barrier | History of Flight | Air & Space Magazine 14 January 2010 20:24 UTC www.airspacemag.com [Source type: FILTERED WITH BAYES]

.Just as light waves will refract towards a region of higher index, sound waves will refract towards a region where their speed is reduced.^ The speed of that wave is limited by the speed of light.
  • DailyTech - German Scientists Declare Speed of Light Broken 14 January 2010 20:24 UTC www.dailytech.com [Source type: General]

^ Just like this sound waves can also be reflected.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

^ Its something 30 seconds from earth to mars if I remember right for a radio wave moving at light speed.
  • DailyTech - German Scientists Declare Speed of Light Broken 14 January 2010 20:24 UTC www.dailytech.com [Source type: General]

.The result is that sound gets confined in the layer, much the way light can be confined in a sheet of glass or optical fiber.^ I’m not trying to sound sarcastic or mean, but the way you said it was like it took so much thought and it was so far out there that it was a feat just to type it out.
  • Damn Interesting • Prepare for Ludicrous Speed 14 January 2010 20:24 UTC www.damninteresting.com [Source type: Original source]

^ Sound travels at 330 meters per second or 740 miles per hour.16 It is very interesting that sound travels much slower than light.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

^ The ear has an acoustic reflex that protects the inner ear from loud sounds in the same way that the pupil of the eye protects the eye by contracting in the presence of bright lights.
  • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

.Thus, the sound is confined in essentially two dimensions.^ Thus two sounds of frequency w 1 and w 2 will be perceived as a single frequency (w 1 +w 2 )/2 but with an intensity that reaches a maximum twice during each cycle of the frequency (w 1 -w 2 )/2.
  • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

.In two dimensions the intensity drops in proportion to only the inverse of the distance.^ Since the force pushing the moon is gravitational, then it is inversely proportional to the square of the distance to the moon.

^ As in optics, the scattered amplitude is proportional to the inverse square of the wavelength, so the scattered intensity is inversely proportional to the fourth power.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

.This allows waves to travel much further before being undetectably faint.^ If the wave is anything but tangential, the wave front will travel much faster than the wave as viewed on the surface, if the wave front is normal, the wave front travels along the surface at a speed of infinity.
  • DailyTech - German Scientists Declare Speed of Light Broken 14 January 2010 20:24 UTC www.dailytech.com [Source type: General]

^ These waves spread out from the vibration and travel away allowing the sound to be heard.
  • 03.04.04: The Physics of Sound: How We Produce Sounds 14 January 2010 20:24 UTC www.yale.edu [Source type: General]

.A similar effect occurs in the atmosphere.^ A similar effect occurs for the wave velocity, as a result of the neglected terms in the substantial derivative, making strong waves travel faster than weak ones.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

.Project Mogul successfully used this effect to detect a nuclear explosion at a considerable distance.^ A strong temperature inversion, or a wind blowing from the source of sound towards the observer, will have the opposite effect, and sound may be heard at a considerable distance.
  • Sound Waves 14 January 2010 20:24 UTC mysite.du.edu [Source type: FILTERED WITH BAYES]

^ The designers of Project Prometheus want to go this route, using a reactor’s energy to power an advanced ion drive (”nuclear electric propulsion”).
  • Damn Interesting • Prepare for Ludicrous Speed 14 January 2010 20:24 UTC www.damninteresting.com [Source type: Original source]

^ The Doppler effect is used in the determination of the distance of galaxies[5,6] (the Hubble constant) and in the Messbauer effect.
  • Physics Demonstrations - Sound 14 January 2010 20:24 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

See also

References

  1. ^ APOD: 19 August 2007- A Sonic Boom
  2. ^ http://www.eng.vt.edu/fluids/msc/gallery/conden/mpegf14.htm
  3. ^ Dean, E. A. (August 1979). Atmospheric Effects on the Speed of Sound, Technical report of Defense Technical Information Center
  4. ^ Everest, F. (2001). The Master Handbook of Acoustics. New York: McGraw-Hill. pp. 262–263. ISBN 0071360972. 
  5. ^ a b U.S. Standard Atmosphere, 1976, U.S. Government Printing Office, Washington, D.C., 1976.
  6. ^ Everest, F. (2001). The Master Handbook of Acoustics. New York: McGraw-Hill. pp. 262–263. ISBN 0071360972. 
  7. ^ Uman, Martin (1984). Lightning. New York: Dover Publications. ISBN 0486645754. 
  8. ^ Volland, Hans (1995). Handbook of Atmospheric Electrodynamics. Boca Raton: CRC Press. pp. 22. ISBN 0849386470. 
  9. ^ Singal, S. (2005). Noise Pollution and Control Strategy. Alpha Science International, Ltd. pp. 7. ISBN 1842652370. "It may be seen that refraction effects occur only because there is a wind gradient and it is not due to the result of sound being convected along by the wind." 
  10. ^ Bies, David (2003). Engineering Noise Control; Theory and Practice. London: Spon Press. pp. 235. ISBN 0415267137. "As wind speed generally increases with altitude, wind blowing towards the listener from the source will refract sound waves downwards, resulting in increased noise levels." 
  11. ^ Cornwall, Sir (1996). Grant as Military Commander. Barnes & Noble Inc. ISBN 1566199131 pages = p. 92. 
  12. ^ Cozzens, Peter (2006). The Darkest Days of the War: the Battles of Iuka and Corinth. Chapel Hill: The University of North Carolina Press. ISBN 0807857831. 
  13. ^ A B Wood, A Textbook of Sound (Bell, London, 1946)
  14. ^ a b Olson, Wayne M. (2002). "AFFTC-TIH-99-02, Aircraft Performance Flight Testing." (PDF). Air Force Flight Test Center, Edwards AFB, CA, United States Air Force.
  15. ^ a b L. E. Kinsler et al. (2000), Fundamentals of acoustics, 4th Ed., John Wiley and sons Inc., New York, USA
  16. ^ J. Krautkrämer and H. Krautkrämer (1990), Ultrasonic testing of materials, 4th fully revised edition, Springer-Verlag, Berlin, Germany, p. 497
  17. ^ APL-UW TR 9407 High-Frequency Ocean Environmental Acoustic Models Handbook, pp. I1-I2.
  18. ^ a b Dushaw, Brian D.; Worcester, P.F.; Cornuelle, B.D.; and Howe, B.M. (1993). "On equations for the speed of sound in seawater". Journal of the Acoustical Society of America 93 (1): 255–275. doi:10.1121/1.405660. 
  19. ^ Mackenzie, Kenneth V. (1981). "Discussion of sea-water sound-speed determinations". Journal of the Acoustical Society of America 70 (3): 801–806. doi:10.1121/1.386919. 
  20. ^ Del Grosso, V. A. (1974). "New equation for speed of sound in natural waters (with comparisons to other equations)". Journal of the Acoustical Society of America 56 (4): 1084–1091. doi:10.1121/1.1903388. 
  21. ^ Meinen, Christopher S.; Watts, D. Randolph (1997). "Further evidence that the sound-speed algorithm of Del Grosso is more accurate than that of Chen and Millero". Journal of the Acoustical Society of America 102 (4): 2058–2062. doi:10.1121/1.419655. 
  • Applied Physics Laboratory – University of Washington, 1994

External links


Simple English

The speed of sound is 1,235 kilometres (767 mi) per hour or 330 metres (1,083 ft) per second in dry air. Sound moves faster through water and solids than air. sound cannot travel through vaccum. The speed of sound is based on temperature. It is lower at low temperatures.

You can calculate the speed of sound like this:

a = \sqrt{\gamma*R*T}

Where: \gamma is the ratio of specific heats (1.4 for air) R is the gas constant (287 N*m/kg*K for air) T is temperature (in Kelvins) sound cannot travel through vaccum. The speed of sound is also known as Mach 1.

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Up to date as of December 23, 2010

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