Bells
A bell is a directly struck idiophone percussion instrument. Most bells have the shape of a hollow cup that when struck vibrates in a single strong strike tone, with its sides forming an efficient resonator. Bells are usually cast from bell metal (a type of bronze) for its resonant properties, but can also be made from other hard materials; this depends on the function. Some small bells such as ornamental bells or cow bells can be made from cast or pressed metal, glass or ceramic, but large bells such as church, clock and tower bells are normally cast from bell metal.