RELATIONSHIP BETWEEN PSYCHOPHYSICAL TUNING CURVES AND SUPPRESSION

This study examined two tone unmasking and auditory frequency selectivity about 3 kHz for the purpose of demonstrating a qualitative relationship between the two. An adaptive 2IFC forward masking procedure was used to collect psychophysical tuning curves (PTCs) and two tone masking data under a quiet and noise condition for the same normal hearing listeners. In the noise condition, a narrowband noise masker, centered one decade down from the probe, was gated on with the tonal masker(s). Kiang and Moxon [J. Acoust. Soc. Am. 55, 620–630 (1974)] have found that low frequency narrowband noise serves to decrease the sharpness of electrophysiological tuning curves by affecting only the tip segments. The data for four highly practiced listeners indicate that the gated noise masker was effective in broadening the PTCs and in lessening the magnitude of two tone unmasking. The mutually reflected changes in tuning curves and in two tone unmasking indicate a close relationship between frequency selectivity and unmasking: the greater the magnitude of unmasking above the center frequency of the PTC, the sharper the tuning of the PTC. © 1979, American Association of Physics Teachers. All rights reserved.