Percussion

The two major categories are membranophones, which add timbre to the sound of being struck, such as drums, and idiophones, which sound of themselves, such as the triangle.

The tambourine is both membranophone and idiophone.

Most percussion instruments have a distinct tone; even drums are tuned. However, a distinction is usually made based on whether the instrument can play a definite pitch or not.

The timpani, xylophone, vibraphone, triangle, tubular bells and glockenspiel all play a definite pitch. The snare drum, bass drum, cymbal, maracas, claves[?], castanets, washboard and wood block[?] do not. However, some percussionists tune drum heads to specific pitches when recording albums or in preparation for specific composer requirements.