Which factor does NOT influence sound propagation speed?

Sound propagation speed is determined by several factors, primarily those related to the medium through which the sound is traveling. The properties of the medium, such as its density and elastic characteristics, play a significant role in determining how quickly sound waves can travel.

The structure of the medium influences sound speed since different materials, such as solids, liquids, and gases, have distinct densities and elastic moduli. For instance, sound travels faster in solids than in liquids, and faster in liquids than in gases.

Humidity in the environment can also affect sound speed, particularly in air. Higher humidity increases the amount of water vapor in the air, which is less dense than the nitrogen and oxygen it replaces. This change leads to an increase in sound speed, as sound travels faster in less dense mediums.

Density of the medium is a critical factor; as it increases, sound speed typically decreases in certain contexts or based on the elastic properties of the medium. However, for gases, if the density changes due to temperature or pressure while maintaining similar elastic properties, the speed can also be influenced.

In contrast, the frequency of sound waves does not affect the speed of sound propagation in a given medium. While frequency may influence the pitch of the sound and affects various phenomena like