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Speed of Sound

Depends on the elastic and inertial properties of the particular medium. It also depends on the temperature of the medium. In air, the speed of sound at 20°C is 343ms^-1.

Gases In a perfect gas where γ = ratio of specific heats P₀ = pressure [Pa] ρ₀ = density [kgm^-3] T = temperature [K] r = specific gas constant [JK^-1kg^-1]
The speed of sound is proportional to the square root of the absolute temperature. where T₀ = 273K c₀ = 331ms^-1 T = gas temperature [K] t_c = gas temperature [°C]

For liquids, the speed of sound is much higher than it is for gases because the density increase for a given pressure increase is much smaller in liquids than in gases. For a pure substance near its critical temperature and pressure, however, the sound speeds of the vapour and liquid phases are not very different.

See also: Sound, Specific Gas Constant.

Subjects: Audio Noise & Vibration Physics

Weblinks:

NPL: Kaye and Laby The speed and attenuation of sound.