What is the main factor that determines how fast sound travels in a medium?

The speed of sound in a medium is fundamentally influenced by its density and elasticity. Density refers to how tightly packed the particles are within the medium, while elasticity indicates how easily the medium can be deformed and return to its original shape.

When comparing different media, sound travels faster in materials that have a high elasticity because the particles can transmit the sound waves more quickly. Likewise, in denser materials, sound can also travel faster because the increased particle interactions facilitate the transfer of sound energy.

For instance, sound travels faster in solids than in liquids and faster in liquids than in gases. This is primarily due to solids having both higher density and greater elasticity than the other states of matter.

Other factors such as frequency, temperature, pressure, and wavelength play roles in sound behavior and propagation but do not directly determine the speed of sound in a medium itself. Frequency relates to the pitch of the sound created, while wavelength is the distance between successive peaks of the sound wave. Temperature and pressure can affect sound speed to some extent, particularly in gases, but the core attributes defining how fast sound travels are primarily the medium's density and its elasticity.