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Chapter 15 Sound

Sound is a mechanical wave that is responsible for the sensory experience of hearing. We can hear a sound wave in air if its frequency lies between \(20\text{ Hz}\) and \(20\text{ kHz}\text{.}\) This range of frequencies is called the audible range. Sound waves of frequencies above \(20\text{ kHz}\) are called ultrasound, and those below \(20\text{ Hz}\) the infrasound.

At the source, sound waves are generated by vibrating objects, such as the vocal chord, a guitar string, membrane of a drum, spaker, etc., and propagate through a medium, most commonly air, from one location to another. Sound is also detected by sound vibrating a membrane, e.g., in the ear drum and in microphone. Since sound is a mechanical wave, it has all the properties of mechanical waves we have described in a previous chapter.