Ward, W.D. (1963). Diplacusis and auditory theory. J. Acoust. Soc. Am. 35, 1746-1747

Following exposure to a series of high-intensity pulses that produced a marked auditory fatigue at 1000 cps and above, significant tonal binaural diplacusis was found to exist at even lower frequencies. The mean shift, for 6 listeners, in the frequency of a tone in the fatigued ear required to match the pitch of a fixed tone in the unexposed ear, was 6.5% at 500 cps, 4.5% at 200 cps, 2.5% at 150 cps, and zero at 100 cps. It is concluded that the perception of the pitch of pure tones can be mediated by the frequency of neural discharge only when the tonal frequency is 100 cps or lower.