An inaccuracy in the reproduction of a signal. In the case of audio, it is normally regarded as being composed of harmonic distortion and intermodulation distortion. But used more broadly, it can also encompass frequency response variations and noise. In the case of lossy compression technologies, some distortion consists of spurious noise (not harmonically related) surrounding the signal. When 'distortion' is quoted as a specification without qualification, it normally refers only to harmonic distortion.