Question

Sound of frequency below 20 Hz is called:

• A. Audio sounds
• B. Infrasonic
• C. Ultrasonic
• D. Supersonics

Hint:

Compare the given frequency with the normal human hearing range of 20 hertz to 20000 hertz.

Answer 1

The Correct Option is B

Step 1: State the hearing range.
The human ear can normally detect sound frequencies from about 20 hertz up to about 20000 hertz.
Step 2: Name the range inside hearing.
Sound with frequency inside 20 hertz to 20000 hertz is called audible or audio sound, since humans can hear it directly.
Step 3: Name the range below hearing.
Sound with frequency below 20 hertz is too low for the human ear to detect, and this range is called infrasonic sound, or infrasound.
Step 4: Separate it from the other terms.
Sound above 20000 hertz is called ultrasonic sound, which is also outside human hearing but on the high end. Supersonic describes a speed greater than the speed of sound, not a frequency at all.
Final Answer: B) Infrasonic.