A slit drum is a hollow percussion instrument. In spite of the name, it is not a true drum but an idiophone, usually carved or constructed from bamboo or wood into a box with one or more slits in the top. Most slit drums have one slit, though two and three slits (cut into the shape of an "H") occur. If the resultant tongues are different width or thicknesses, the drum will produce two different pitches. It is used throughout Africa, Southeast Asia, and Oceania. In Africa such drums, strategically situated for optimal acoustic transmission (e.g., along a river or valley), have been used for long-distance communication.