A membranophone, in the Hornbostel-Sachs classification system, is an instrument that produces sound through the vibrations of a membrane. Membranophones, in some form, have existed for more than 4,000 years. Usually a membranophone is a drum which makes a sound when the membrane is hit by hands or sticks. Some drums can be set to different pitches by tightening or loosing the tension on the skin.
There are four basic types of drums:
· Barrel: a drum with bulging sides such as the conga.
· Conical: a drum whose head is larger than its base.
· Cylindrical: a drum with a long, narrow body and straight, even sides, like the timbales.
· Waisted: a drum that is narrower in the center than at both ends.
· Goblet: a drum that stands on a narrow base.
· Footed: a drum with feet carved from its body.
· Long: a drum whose length significantly exceeds its diameter.
Kazoos are also considered among the membranophones because the sounds they generate are the result of a vibrating membrane stretched. This places in a class of instruments known as mirlitons.