Phase

Phase, in sound theory at least, describes the time relationship between two or more waveforms. Phase is measured in degrees, and can be easily demonstrated using sine waves. A sine wave starts when its cycle starts. This is denoted by 0°. One complete cycle signifies 360° (which is also 0°), half a cycle 180°, a quarter of a cycle 90° and so forth. If one sine wave reaches a quarter of its cycle when a cycle begins on an identical waveform, the two are said to be 90° out of phase (Figure 11.1).