- A form of distortion in which harmonics which were not present in an input signal are present in the output signal.
- A form of distortion in which harmonics which were not present in a sinusoidal input signal are present in the output signal. This results in the alteration of the original waveform. The generation of such undesired harmonics is a result of non-linearity of the component, circuit, device, piece of equipment, system, or transmission line in question.
- A measured amount of harmonic distortion (2). It is usually expressed as the ratio of the amplitude of a given harmonic to the amplitude of the fundamental frequency, multiplied by 100 to obtain a percentage. If the squared amplitudes of each of these ratios of distorting harmonics are added, the square root is taken from the result, and this number is then multiplied by 100 to obtain a percentage, it is called total harmonic distortion. This value is frequently used as an expression of the performance of audio components, especially amplifiers.
- A form of distortion in which there is a disproportionate reproduction of harmonics.