 Speed of sound

The speed of sound is the propagation speed of a small mechanical pressure disturbance through a medium. Compression creates a restoring pressure gradient, while the medium's mass density supplies inertia. For an inviscid fluid undergoing locally isentropic disturbances,A stiffer pressure response increases the speed. For a perfect gas, this becomes $c_s^2=\gamma p/\rho$, with $\gamma$ the heat capacity ratio.

The disturbance travels while individual fluid parcels undergo much smaller oscillatory motions; acoustic particle velocity and propagation speed are different quantities. Timing a short sound pulse between two sensors a known distance apart gives a direct measurement after accounting for electronic delays. If heat exchange maintains a different thermodynamic response during compression, the relevant derivative changes, as in the isothermal sound speed. The formula also presumes a wavelength and timescale for which the continuum model is appropriate.

The speed of sound is the distance that sound waves travel through a medium (such as air, water, or solid materials) in a given period of time. In general, the speed of sound varies depending on the medium through which it is traveling, as well as environmental conditions such as temperature and pressure. In air at sea level and at a temperature of about 20 degrees Celsius (68 degrees Fahrenheit), the speed of sound is approximately 343 meters per second (1,125 feet per second).