Sound Engineering Explained, 2nd Edition

1   Sound waves

Part 2

The velocity of sound waves

This varies slightly with the temperature of the air but not, as is often supposed, with the air pressure, at least not over all normally encountered ranges of temperature and pressure.

At 0°C, the velocity of sound waves in air can be taken as 331 m/s, and this increases by 0.6 m/s for every 1°C rise in temperature.

Thus:

at –10°C the velocity is 325 m/s

at +10°C it is 337 m/s

at +20°C it is 343 m/s.

340 m/s is a reasonable figure to use for normal room temperatures.

In substances other than air, sound waves travel at quite different velocities (Table 1.1).

The high velocity of sound in helium, about three times that in ordinary air, accounts for the high-pitched voices of divers and others ...