The timpani, also known as kettledrums, are constructed of a large copper bowl with a drumhead made of animal skin stretched across the top. They are struck with felt tipped wooden sticks. Timpani were the first drums to be used in the orchestra, joining the ensemble over 300 years ago. Timpani are a tuned instrument and produce a specific pitch that is determined by the drum's size. Most orchestras use three or four timpani of varying sizes. The pitch is fine-tuned by tightening the drumhead with keys and foot pedals.