Question

The phenomenon of sound wave propagation has two main features.

• The change in density corresponds to a change in pressure.why?

Answer 1

Sound is a longitudinal wave and moves forward by compression and rarefaction of the particles in a medium. This compression and rarefaction is indeed seen as variations in density or pressure in the medium due to the compressions.
The pressure is some function of the density. The density of the medium is directly proportional to the sound pressure.So we say that the change in density corresponds to a change in pressure.