Timpani are the big drums you see at the back of an orchestra. They look like huge copper or fibreglass bowls with skin stretched over the top, so people also call them kettledrums. Two things make them special. First, each one is tuned to a note, so a timpani player is not just keeping time — they are playing pitches, and they change the pitch with a foot pedal while the music goes on. Second, they usually come in a set of two, three, four or more, played by one person with soft-headed sticks. That is why the word is almost always plural: you say 'the timpani are' and 'he plays timpani', not 'a timpani'. The single drum is a timpano, but honestly, most musicians never say that word out loud. In a school or a shop you will more often hear 'kettledrums', and in rock or film-music talk people just say 'the big drums'. When writers use the word outside music, they use it for a deep rolling sound — thunder, or a heavy heartbeat — because that low boom is what timpani are famous for.

定音鼓（管弦樂團裡那種大銅鍋鼓，可以調音高）