Intelligibility of Frequency-Shifted Speech
W. H. Darnall, Jens Birch · The Journal of the Acoustical Society of America · 1963
An electronic system has been developed that allows a speech spectrum, initially confined to a band of frequencies from 300 to 3300 cps, to be deviated from its normal spectral location. The perturbation is sinusoidal in nature and controls both the amount of deviation and the rate of deviation of the spectrum about its normal position. This system, in conjunction with an appropriate psycho-acoustical test, provides a functional relationship between intelligibility and the independent variables, deviation and rate of deviation.