| medium | v/m s–1 |
| air at 0 °C | 331 |
| helium at 0 °C | 965 |
| fresh water at 20 °C | 1480 |
| steel | 5960 |
The
speed of sound depends on the
medium through which the sound is transmitted.
Sound travels
faster through media that are
more rigid (less elastic).
Even though more rigid materials are more difficult to deform, the deformation snaps back to the equilibrium position more readily.
In general sound travels faster in solids than in liquids than in gases.
Compare the speed of sound in the gases air and helium with the speed in water and steel.
Sound travels
faster through media that have
lighter particles.
Note that the speed of sound is slower in the gas air than in helium.
This is because air has heavier particles (N2 and O2 molecules) than the gas helium (He).
The speed of sound does
NOT depend on the frequency of the sound.
The wavelength is different for transmission of sound of the same frequency through a given medium.
The wavelength can be calculated from the velocity and frequency of the sound using the same relationship as for other waves (v = f λ).
The speed of sound in gases
depends on the temperature as shown by the relationship below that derives from the ideal gass equation.
| v = | √ | γP | = | √ | γRT | | γ ratio of heat capacities
T temperature in kelvin | R ideal gas constant
M molar mass in kg mol–1 |
| ρ | M |
The particles in the gases are moving more rapidly at higher temperatures, and this increases the speed at which the sound waves are propagated