Percussion instruments produce sound when struck, shaken, or scraped. They fall into two broad categories: those that produce definite pitch and those that produce sound without a definite pitch. The Timpani, Celesta, and Xylophone belong to the first category of pitched instruments. The Snare Drum and Cymbals belong to the second category of unpitched instruments. The Celesta uses a keyboard as a control device to create the sounds of a glockenspiel. That is why it is traditionally thought of as a member of the percussion family. Click the Play button for a demonstration.