ICSE Class 9 Answered

A sound wave is the pattern of disturbance caused by the mechanical vibration .

For example , the organs like lips, tongue, jaw, and teeth are used to give shape to the sound produced

or the correct word produced by the human.In string instruments, vibration of strings give sound.

Vibration of air column gives sound in the pipe instruments.

This energy of mechanical vibration travelling away from the source of the sound.

Sound waves are longitudinal waves. This means that the propagation of vibration of particles is parallel to

the energy wave propagation direction. Hence a medium is required to propagate the sound wave.

When the molecules/atoms in the medium are set in vibration due to sound wave, then they move back and forth.

This continuous back and forth motion results  in a high-pressure and a low-pressure region in the medium.

These high- pressure and low-pressure regions are termed compressions and rarefactions, respectively.

These regions are transported to the surrounding medium resulting in the sound waves travelling in the medium.