The Lateralization of the Residue for Preselected Interaural Phase Disparities

Abstract

Three signal types were employed binaurally as stimuli on a lateralization experiment: a 200-Hz pure tone, a 2400-Hz sinusoid, and an AM waveform created by modulating 2400 Hz with 200 Hz. The latter signal type gave rise to a low-pitched residue. The subjects were required to achieve a midline image by altering the intensity of the signal at one ear to compensate for preselected phase delays in the stimulus routed to the contralateral ear. When statistical comparisons were made between the results for (1) the AM signal (residue) and the 200-Hz tone, (2) the AM stimulus (residue) and the 2400-Hz signal, and (3) the 200-Hz sinusoid and the 2400-Hz pure tone, the residue and the 200-Hz signal required similar compensatory intensity changes for the interaural phase difference to achieve a centered tone image, whereas the disparate phase conditions did not affect the intensity relationship required for a midline experience for the 2400-Hz binaural signals. The fact that both time and intensity alterations shift the perceptual location of the residue and the 200-Hz tone in the same way implies that the moment of neural excitation is mediated for the residue by the same rules that govern a comparable low-frequency sinusoid.