MP Board · Class 9 · Science · SoundWhat is the audible range of hearing for human beings? Explain infrasonic and ultrasonic sounds with appropriate examples.

Audible Range of Hearing:\nThe range of sound frequencies that a normal human ear can detect ranges from $20\text{ Hz}$ to $20,000\text{ Hz}$ ($20\text{ kHz}$).

Infrasonic Sound (Infrasound):\nSound waves having frequencies below $20\text{ Hz}$ are called infrasonic sounds. Humans cannot hear infrasound.

• Examples/Sources: Produced by natural phenomena like earthquakes, volcanic eruptions, and ocean waves. Animals like elephants, rhinoceroses, and whales produce infrasound to communicate over long distances.

Ultrasonic Sound (Ultrasound):\nSound waves having frequencies above $20,000\text{ Hz}$ are called ultrasonic sounds.

• Examples/Sources: Produced naturally by bats, dolphins, and porpoises for navigation and prey location. Used artificially in medical ultrasonography and non-destructive testing.