Sounds of which frequencies are called infrasonic sounds or infrasound?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Below 20 Hz
The human ear hears sounds of frequencies from about 20 Hz to 20,000 Hz (20 kHz). Sounds below this range, below 20 Hz, are called infrasonic sounds (infrasound): a vibrating pendulum, earthquakes and whales produce them, and elephants and rhinoceroses use them to call to one another. Sounds above 20 kHz are ultrasonic (ultrasound), used by bats and dolphins and in medical scans.