Sound waves with a frequency below 20 Hz are called
(a) infrasonic waves
(b) ultrasonic waves
(c) ultrasound
(d) none of these

Sound waves whose frequency is greater than 20000 Hz is called ___.

Sounds having frequencies lower than 20 Hz are called:

What is : periodic time, simple harmonic motion , wave, wave length, amplitude, frequency, wave velocity, audible sound, infrasonic sound, ultrasonic sound, echo and reverberation

Sound of the frequency below 20 Hz is known as