Sound is a mechanical disturbance produced by passage of energy through a medium which may be gas, liquid or solid. Every sound has a particular frequency, a wavelength, its own velocity and an intensity.

Sound energy is transmitted through a medium in the form of cycles or waves. Each wave consists of a peak and a trough. The peak coincides with an adjacent group of molecules moving towards each other (compression phase). The trough coincides with adjacent group of molecules moving away from each other (rarefaction phase).

Frequency of sound is the number of times per second, sound undergoes a cycle of rise and fall. It is expressed in cycles per second, or hertz (Hz) and multi