A source emits sound at a fixed constant frequency f .
If the source moves away from you faster than the speed of sound in air, you do not hear any frequency but instead a 'sonic boom.'

Question

A source emits sound at a fixed constant frequency f . 
If the source moves away from you faster than the speed of sound in air, you do not hear any frequency but instead a 'sonic boom.'

Quizplus · Accepted Answer

When a source moves faster than the speed of sound, it creates a shock wave, resulting in a sonic boom, and the sound waves do not reach the observer until the source has passed.

A Source Emits Sound at a Fixed Constant Frequency F