Sound having a frequency below 20 Hz is known as

Options

  • A. Ultrasonic sound
  • B. Infrasonic sound
  • C. Supersonic sound
  • D. More than one of the above
  • E. None of the above

Correct Answer (Detailed Explanation is Below)

B. Infrasonic sound

Detailed Explanation

Infrasonic sound has a frequency below approximately 20 Hz. Humans generally cannot hear such sounds, although some animals can detect low-frequency sounds. Natural sources include earthquakes, volcanic activity and some atmospheric phenomena. Remember the distinction: infrasonic < 20 Hz, audible ≈ 20 Hz–20 kHz, ultrasonic > 20 kHz.