Question

multiple choice question
sound waves with frequencies greater than 20,000 hz are known as __, whereas those with frequencies of less than 20 hz are known as __
constructive; destructive
reverberations; echoes
ultrasonic; infrasonic
subsonic; supersonic

Explanation:

Ultrasonic sound waves have frequencies above 20,000 Hz. Infrasonic sound waves have frequencies below 20 Hz. Constructive and destructive refer to wave interference. Reverberations and echoes relate to sound reflection. Subsonic and supersonic are about speed relative to the speed of sound.

Answer:

ultrasonic; infrasonic