Audible and Inaudible sounds

Audible and Inaudible sounds

               We know that sound is produced by vibrating bodies. The number of vibrations produced in one second is called the frequency of vibrations. the unit of frequency is hertz(Hz).

Audible sound

              Sound waves of frequencies ranging from 20 Hz to 20,000 Hz are audible to human ear. This is known as the 'audible frequency range'.

Inaudible sound

              Vibrations having frequencies below 20 Hz are called 'infrasonic'. The vibrations of the earth produced during an earthquake are infrasonic waves.

               Sounds of frequencies greater than 20,000 Hz are known as 'ultrasonic'. These vibrations are not audible to the human ear. Some animals such as bats and dogs can hear ultrsonic frequencies.

                 Bats can produce sounds of frequencies above 70,000 Hz.