The speed of the sound depends on the density of the medium through which it is travelling.
The particles in the solid medium are closely packed. Hence, the density is high. Information from one molecule to another molecule travels faster in the solid medium.
In liquid, the molecules are farther apart than in solids. Hence, the density is low for liquids.
In gas, the molecules are very loosely dispersed. The speed of the sound wave will be maximum in steel.
Explanation:
Sound is a mechanical wave that needs a medium to travel.
The speed of sound is maximum in solid, then it is in liquid and it is the slowest in gases.
The speed of sound remains almost the same for all frequencies in a given medium under the same physical conditions.