Question

71) Sounds of frequency below 20Hz is called​

Answer 1

INFRASOUND :

• Sound of frequency below 20Hz is called infrasound.
• Infrasound is too low-pitched for humans to hear.
• People use this frequency range for monitoring earthquakes and volcanoes, charting rock and petroleum formations below the earth.

Answer 2

Infrasonic

Explanation:

• Low-frequency sound is often described as Infrasound.  It explains sound waves which are a frequency below the lower limit of sound frequency which is generally 20 Hz.
• At this frequency hearing becomes less sensitive as frequency decreases. So for humans to hear infrasound, the sound pressure must be higher than 20Hz.
• The ear is the primary organ for sensing infrasound, but at higher frequencies it is possible to feel the sound vibrations in various parts of the body.  
• The study of these low sound waves is known as infrasonic .

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