Drums are able to produce sound when the stretched layer on top, the head, vibrates and amplifies the hollow center. Drums of different sizes produce different sounds due to varied hollow volumes.
Drums are one of the oldest instruments known to humans. Little is required to construct a drum, making it exceptionally easy for ancient civilizations to create and use.
A basic drum consists of two parts: the tightly stretched membrane covering the top of the drum (the head), and the hollow casing underneath. When the head of a drum is struck, it vibrates and moves air around it, creating sound waves. Normally, the sound would be somewhat dull and quiet, no matter how tightly stretched the head. However, the hollow body, beneath the head, amplifies the sound by creating a miniature echo chamber. The sound waves vibrate through the body and, upon exiting, are noticeably louder.
It is possible to achieve various types of sounds from a drum through the use of different size and shape bodies, as well as hitting it with different instruments.
A standard drum set includes a smaller drum, called the snare drum, that produces a loud sharp sound, as well as a large piece, called a bass drum, that produces a deep, low sound.