The Basics: for any sound to be made air has to vibrate! Something has to move back and forth to cause the air to vibrate. A good example is a guitar string which vibrates at certain frequency which causes the air to move at that frequency. Middle C has a frequency of 261.63Hz, which means the air vibrates 261.63 times per second. This principle applies to all instruments. The reason why different instruments sound different at the same frequency is because there are other frequencies in the sound. It sounds like a middle C because that frequency is the loudest amongst the other frequencies. Each instrument has a unique profile which colors the sound and give them unique character and timbre. buku mimpi
Applied to acoustic drum kits the drum head creates the sound. There are a few ways in which the vibrating head creates vibrating air. The drum head itself immediately vibrates the air. Then there is the reflected sound off the inside surface of the drum, normally plain wood, treated wood or lacquer. The third way is the sound that the drum shell emits because it is vibrating caused by the vibrating drum head. This third type of sound creation, the shell vibration, is of importance in this article. Just like the guitar string we know, the harder the wood (think tighter) and more rigid it is the higher the frequency the better the resonance (the sound lasts longer) and the softer the wood the lower the frequency damped quicker.