AUDIBLE, INFRASONIC AND ULTRASONIC WAVES
Sound of Class 9
The human ear is sensitive to sound waves of frequency between 20Hz to 20 kHz. This range is known as audible range.
e.g. By vibrating sitar, guitar, organ pipes, flutes, shehnai etc.
A longitudinal elastic wave whose frequency is below the audible range i.e. 20 Hz, is called an infrasonic wave.
it is generally generated by a large source.
e.g. : Earthquake.