A reference distortion system using modulated noise
H.B. Law, Robert A. Seymour · Proceedings of the IEE Part B Electronic and Communication Engineering · 1962
A reference distortion device has been developed, initially for use in the subjective assessment of pulse-code-modulated telephony links. Noise is amplitude-modulated by the speech signal, and then added to the signal in variable proportion, to produce controllable distortion comparable with the effect of quantizing noise.