Speed of Sound in Air

The speed of sound in a gas depends primarily on the temperature, and can be estimated using the following formula from the kinetic theory of gases:^F.13

where the adiabatic gas constant is for air at standard temperature and pressure (STP) (standard temperature is zero degrees centigrade), is the ideal gas constant for air (in meters-squared per second-squared per degrees-Kelvin-squared), and is absolute temperature in degrees Kelvin (which equals degrees centigrade + 273.15). For example, at zero degrees centigrade (32 degrees Fahrenheit), the speed of sound is calculated to be 1085.1 feet per second. At 20 degrees centigrade, we get 1124.1 feet per second.

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written by Julius Orion Smith III
Julius Smith's background is in electrical engineering (BS Rice 1975, PhD Stanford 1983). He is presently Professor of Music and Associate Professor (by courtesy) of Electrical Engineering at Stanford's Center for Computer Research in Music and Acoustics (CCRMA), teaching courses and pursuing research related to signal processing applied to music and audio systems. See http://ccrma.stanford.edu/~jos/ for details.