Sound of frequency below 20 Hz are called (A) Audio sounds (B) Infrasonics (C) Ultrasonics (D) Supersonics

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Points to Remember:

  • Sound is a form of energy that travels as waves.
  • The frequency of a sound wave determines its pitch.
  • Human hearing range is typically 20 Hz to 20,000 Hz.
  • Sounds outside this range have specific names.

Introduction:

Sound is a longitudinal wave that propagates through a medium (like air, water, or solids). It’s characterized by its frequency (measured in Hertz, Hz), which corresponds to the pitch, and its amplitude, which corresponds to the loudness. The human ear can typically detect sounds within a frequency range of approximately 20 Hz to 20,000 Hz. Sounds outside this range are imperceptible to humans but have important applications and implications in various fields. The question asks us to identify the term for sounds with frequencies below 20 Hz.

Body:

Understanding Sound Frequency Ranges:

The audible range of human hearing is limited. Sounds with frequencies below the human hearing threshold (20 Hz) are called infrasound, while those above the upper threshold (20,000 Hz) are called ultrasound. Supersonic refers to speeds exceeding the speed of sound, not frequencies. Audio sounds encompass the entire range of frequencies audible to humans.

  • Infrasonics (Below 20 Hz): These low-frequency sounds are produced by various natural phenomena like earthquakes, volcanoes, and ocean waves. They can also be generated by human activities such as explosions and heavy machinery. While inaudible to humans, infrasound can have physiological effects, causing feelings of unease, pressure, or even nausea. Some animals, like elephants and whales, can perceive and use infrasound for communication over long distances.

  • Audio Sounds (20 Hz – 20,000 Hz): This is the range of frequencies that humans can hear. This range encompasses the sounds we experience daily, from speech and music to environmental noises.

  • Ultrasonics (Above 20,000 Hz): These high-frequency sounds are used in various applications, including medical imaging (ultrasound scans), industrial cleaning, and sonar. Bats and dolphins use ultrasound for echolocation.

  • Supersonics: This term refers to speeds faster than the speed of sound, not frequencies. It’s commonly used in the context of aircraft and projectiles.

Correct Answer:

The correct answer is (B) Infrasonics. Sounds with frequencies below 20 Hz are called infrasonics.

Conclusion:

The question tested the understanding of sound frequency ranges. We learned that sounds below 20 Hz are classified as infrasonics, those between 20 Hz and 20,000 Hz are audio sounds, and those above 20,000 Hz are ultrasonics. Supersonics refers to speed, not frequency. Understanding these different frequency ranges is crucial in various scientific and technological fields, from understanding animal communication to developing advanced medical imaging techniques. Further research into the effects of infrasound on human health and the potential applications of ultrasound technology continues to be an area of active exploration, highlighting the ongoing importance of understanding the physics of sound.

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