SPEED OF SOUND
The speed of a SOUND WAVE varies greatly when propagated in different media, the PROPAGATION velocity depending on the elasticity (or compressibility), temperature and density of the medium in question.
See also: ACOUSTIC IMPEDANCE, PARTICLE VELOCITY, REFRACTION, SOUND PROPAGATION.
In air, for instance, temperature and atmospheric pressure are significant factors. At 0° Centigrade and 1.013 x 105 Newtons per square meter (normal atmospheric pressure), the speed of sound is 331.5 meters/sec, i.e. 1087 ft/sec or 740 miles/hour. At 20°C (68°F) the speed is 1130 ft/sec or 344 m/sec. Propagation speeds for other media are given in the chart below. For each degree Centigrade increase in temperature, the speed of sound increases by 0.61 m/sec or 2.0 ft/sec.
See: DOPPLER EFFECT, ECHOLOCATION, SONAR, SONIC BOOM, SUBSONIC, SUPERSONIC, SUPERSONIC TRANSPORT, WAVELENGTH.
Speed of Sound in Various Substances
Substance Temperature (°C) Speed (m/sec) Speed (ft/sec) CO2 0 258 816 CO2 35 274 900 Air 0 331.5 1,087 Air 20 344 1,130 Water Vapor 35 402 1,320 Helium 20 927 3,040 Hydrogen 0 1,270 4,165 Water 15 1,437 4,714 Steel - 5,000 16,400