Laplace’s formula, for the speed of sound in air (and other gases) is
\(v=\sqrt{\frac{γP}{ρ}}\)
From this formula, and the known formulae for gases, we can conclude that
(i) Speed of sound, in a given gas, does not change with ‘change in pressures’ (This is because a change of pressure causes a proportionate change in density; the ratio p/ρ , therefore, remains constant).
(ii) The speed of sound, in a given gas, depends on its temperature (on the kelvin scale) as per the relation
i.e., the speed of sound, in a given gas, is directly proportional to the square root of its absolute (or kelvin) temperature.
One can also conclude that the presence of humidity (i.e., water vapour), in air, leads to an increase in the speed of sound.
