All true drums belong to the membranophones. A drum has one or two heads of skin or plastic stretched over a resonator or over a narrow frame. Kettledrums, having a single head over a bowl-shaped resonator, are produced in all sizes. Orchestral kettledrums are tuned by means of hand screws or pedals, whereas some non-Western types are tuned with paste or heat applied to the head, or by manipulating the lacing which attaches to the head or heads. Hard and soft beaters offer tonal variety. In India the technique of playing small kettledrums (the baya in the pair called tabla) with the hands is a subtle art. Cylindrical drums, usually unpitched, vary in size from huge basses drawn on wagons in parades, to shallow, waist-slung drums equipped with snares that intensify the sound. In parts of Africa and the Pacific Islands sacred drums are taboo to the uninitiated; their wood bodies are elaborately carved and decorated, and revered drums occupy huts to which votive offerings are brought. Slender, elongated drums with reptile-skin heads glued on with human blood accompany male ritual dances in New Guinea. Some Native Americans accompany tribal dances and chants on broad, shallow drums beaten by several players at once. A light hand-held frame drum is played by Eskimo shamans; it resembles Asian shamans' drums. The tambourine is a frame drum that usually has rattles attached to the frame; it is both struck and shaken and is sometimes rubbed.
The rommelpot is a Flemish friction drum played as a toy; rubbing a stick or string protruding through its head causes the head to vibrate. A more important membranophone is the mirliton. Not actually an instrument in its own right, but rather a tone modifier, the mirliton is a thin membrane attached over a hole in a resonator, adding a buzzing quality to the sound. One popular mirliton, the kazoo, disguises the voice. Other mirlitons enrich the tone of instruments as diverse as African xylophones, drums, and Chinese flutes.