Range of Hearing

(i) Range of hearing in human is 20 Hz to 20000 Hz.

→ Children younger than 5 years and dogs can hear upto 25 Khz.

(ii) The sounds of frequencies lower than 20 Hz are

known as ‘infrasonic sounds’

→ A vibrating simple pendulum produces infrasonic sounds.

→ Rhinoceroses communicate each other using frequencies as low as 5 Hz.

→ Elephants and whales produces infrasonic waves.

→ Earthquakes produces infrasonic waves (before shock waves)

which some animals can hear and get disturbed.

(iii) The sounds of frequencies higher than 20 KHz are known as ‘ultrasonic waves’.

→ Dogs, parpoises, dolphins, bats and rats can hear ultrasonic sounds.

→ Bats and rats can produce ultrasonic sounds.