Question

Explain why a sound is heard when a person snaps their fingers.

Answer 1

There is a good explanation of the physics related to the sound made when snapping the fingers ar this link:
http://en.wikipedia.org/wiki/Finger_snapping

Answer 2

It is because we have the MALLEUS, INCUS, and STAPES in our ear. They process sound vibrations or frequencies, which allows us to hear the sound and allows our brain to recognize the sound.

Answer 3

@suchandrarao is describing the popping sound when someone cracks their knuckles, not the snapping of fingers. The snap is heard when the middle finger hits the base of the thumb.