Permissible Amplitude Distortion of Speech in an Audio Reproducing System

This paper gives the experimental results of a brief study of permissible amplitude distortion in an audio reproducing system having a relatively flat frequency-response characteristic, from 80 to 14,000 cycles. The effect of distortion on the character of reproduction was observed when the transmission band was cut off at 5000 cycles, 8000 cycles, and 14,000 cycles. Distortion was introduced by overloading an amplifier so calibrated that the amount of harmonic outupt being generated was known for various input intensities and attenuator settings. A cathode ray oscillograph was used across the input as a peak indicating voltmeter. It was found that the permissible amount of distortion is lower, the greater the frequency range of the reproducing system, and also that a certain amount of second harmonic is less objectionable than the same amount of third harmonic distortion.