<P> The drum is a member of the percussion group of musical instruments . In the Hornbostel - Sachs classification system, it is a membranophone . Drums consist of at least one membrane, called a drumhead or drum skin, that is stretched over a shell and struck, either directly with the player's hands, or with a drum stick, to produce sound . There is usually a resonance head on the underside of the drum, typically tuned to a slightly lower pitch than the top drumhead . Other techniques have been used to cause drums to make sound, such as the thumb roll . Drums are the world's oldest and most ubiquitous musical instruments, and the basic design has remained virtually unchanged for thousands of years . </P> <P> Drums may be played individually, with the player using a single drum, and some drums such as the djembe are almost always played in this way . Others are normally played in a set of two or more, all played by the one player, such as bongo drums and timpani . A number of different drums together with cymbals form the basic modern drum kit . </P>

A drum skin is stretched over one end of a pipe