Basic Physics of Sound http://1.bp.blogspot.com/_4-6muvFIO_0/SZokCX7Hq5I/AAAAAAAAAKQ/Huc4EguWbM0/s400/anatomy.gif What we perceive as sound is simply defined as sound waves traveling through the air, being received by our ears, and then recognized as various sounds by the human brain. As seen in the picture above however, a sound wave has quite a few different parts which are defined below. Crest: The topmost point of the wave medium or greatest positive distance from the rest position. Trough: The bottommost point of the wave medium or greatest negative distance from the rest position. Wavelength (L): The distance from crest to adjacent crest or from trough to adjacent trough or from any point on the wave medium to the adjacent corresponding point on the wave medium. Amplitude (A): The distance from the rest position to either the crest or the trough. More vocabulary! Frequency (f): The number of wavelengths to pass a point per second. Period (T): The time it takes for one full wavelength to pass a certain point. Since period and frequency are reciprocals of each other. They can be defined as: T = 1/f & f = 1/T The speed of a sound wave is always a ratio of distance to time. It can be expressed as below. v = L/t or v = Lf