Timpani
Timpani are different from other drums because they are tuned to certain musical notes. A timpanist will often describe the drum as being "in voice" (or out of voice, as the case may be) when it is correctly tuned. To play it, it is hit with a special drumstick or "timpani mallet". Other drums that are used in orchestras and bands make a sound rather than a note, and are not tuned. A player normally sits with a group of two, three or four timpani around him, which is why the name timpani is in the plural.