You should know that the mechanichal waves are those waves which require a medium for propogation. Sound needs a medium (solid, liquid or gas) for their propogation and can't travel without a medium.Therefore sound wave is a mechanical wave.

Introduction:
Sound waves are a type of wave that require a medium to propagate. They are called mechanical waves because they require the displacement of particles in a medium to travel from one point to another. Sound waves are commonly found in our everyday lives and are responsible for our ability to hear.

Definition of mechanical waves:
Mechanical waves are waves that require a medium to propagate. They are characterized by the transfer of energy through the motion of particles in the medium. These waves cause the particles in the medium to oscillate back and forth, without actually displacing the particles permanently.

Propagation of sound waves:
Sound waves are produced by a vibrating source, such as a person speaking or a musical instrument. The source creates vibrations that are transferred to the surrounding particles in the medium, usually air. These particles then pass the vibrations to the adjacent particles, creating a domino effect that leads to the propagation of the sound wave.

Medium as a requirement:
Sound waves cannot travel in a vacuum because they require a medium to transmit the vibrations. In a vacuum, there are no particles to vibrate and carry the sound wave. However, sound waves can travel through various mediums such as air, water, and solids. The speed of sound varies depending on the properties of the medium it is traveling through.

Particle displacement:
As sound waves propagate through a medium, the particles in the medium vibrate in a back-and-forth motion. However, these particles do not permanently move from their original position. Instead, they oscillate around their equilibrium position, returning to their original position after the wave passes through. This characteristic of mechanical waves distinguishes them from other types of waves, such as electromagnetic waves.

Conclusion:
In conclusion, sound waves are called mechanical waves because they require a medium to propagate and rely on the displacement of particles in that medium to transmit energy. They travel through a series of particle interactions, causing the particles to oscillate without permanently displacing them. Understanding the nature of sound waves as mechanical waves helps us appreciate the mechanisms by which sound is produced, transmitted, and eventually heard by our ears.