PSYCHOPHYSICAL TUNING CURVES - RESTRICTING THE LISTENING BAND TO THE SIGNAL REGION

Psychophysical tuning curves were generated for three listeners by determining threshold for a 2.0-kHz sinusoid fixed at 20 dB SPL as a function of the level and frequency of a narrow-band noise masker. Then the listening band available to the listeners was restricted by inserting a low-level (≃18 dB SPL) stationary masker at 1.8 kHz. The stationary masker alone did not mask the signal but it depressed the upper branch of the tuning curve by as much as 20 dB. The lower branch of the curve was essentially unaffected. When the low-level stationary masker was repositioned to 2.2 kHz the effect was reversed; the lower branch of the tuning curve was depressed but the upper branch was little changed. The combined results show that the thresholds on the two branches of the tuning curve are based on information in different frequency regions and indicate that even at reasonably low signal levels the traditional psychophysical tuning curve overestimates the frequency selectivity of the ear. © 1979, Acoustical Society of America. All rights reserved.