distortion

distortion, in electronics, undesired change in an electric signal waveform as it passes from the input to the output of some system or device. In an audio system, distortion results in poor reproduction of recorded or transmitted sound. In passing through an electronic device, the amplitude of an input signal may be changed. For example, any voltage that is applied to an amplifier may be increased by a factor of 10. Amplitude distortion occurs when this factor is not the same for all input voltages. Frequency distortion occurs when the amplitudes of the different frequency components of an input signal are changed by a factor that is not the same for all frequencies. Phase distortion occurs when there is a phase shift between a system's output- and its input-signal components. It occurs because the time of propagation through a system can vary with frequency. Intermodulation distortion, also known as cross modulation, results from the mixing of signals in a non-linear system; the output will contain the sums and differences of the input signals' harmonics. Some kinds of distortion are subjectively more objectionable than others.