The drummer may choose to strike the head, the rim, or the shell. If you strike the head, a cracking sound is produced because the bottom head is against which the snares vibrate. The snares could be controlled with a lever placed on the strainer so that the sound produced will only be like a tom-tom. They were also often used for dances about unpleasant ideas such as nightmares or demons. It was also mentioned in the Lully s ballet Flore in 1669 that castanets were also used for African Dances. Castanets were played to evoke or give out a Spanish aura in many works such as in Carmen by Georges Bizet and Espa a by Emmanual Chabrier. The increase of volume is done by the sound box consisting of a resonant cavity and a soundboard. The vibration of the strings also causes vibration of the soundboard. It has a much larger area than the strings which means that is also produces a louder sound. Sound waves are created coming from the back and front panels as the soundboard is vibrating. Shapes of didgeridoos Didgeridoos do not have a standard or uniform size or shape. The tube s length and its almost conical shape affect the acoustic performance of every individual instrument. The didgeridoos that are in demand are those measuring from 1 meter to 1.6 meters. The lowest tones that could be heard from these are in the range of 70 to 100 Hertz. The Clarinet is usually wooden and vertically played. It has a wider bore which has a single reed and this, when activated, vibrates against a removable mouthpiece. Traditionally, the wood used is granadilla wood from South America, Africa, or Asia. Nowadays, it is most common as a B-flat clarinet which is about sixty centimeters in length. The virginals is a simpler and smaller harpsichord with only a string for every note while the ottavino are similar to virginals but are at four foot pitch. It is sometimes referred to as double virginals. The clavicytherium has its strings and soundboard placed perpendicularly in front of the player just like the upright piano.