Off-frequency listening: Effects on psychoacoustical tuning curves obtained in simultaneous and forward masking

Abstract

Off‐frequency listening—the use of information in different frequency regions to improve performance in masking tasks—has been reported to influence psychoacoustical tuning curves measured in simultaneous masking. The present experiment was designed to establish whether suppression has an effect on off‐frequency listening. Psychoacoustical tuning curves were obtained from three observers in both simultaneous and forward masking, by determining the masker level needed to mask a 2.0‐kHz probe as a function of the masker frequency. A probe level of 10 dB SL and narrowband noise maskers were used. After obtaining the conventional tuning curves, a fixed masker, at either 1.8 or 2.2 kHz and 10 dB below the corresponding tuning‐curve threshold, was added to limit off‐frequency listening. In both simultaneous and forward masking, the branch of the tuning curve opposite the fixed masker was shifted downwards, but to a greater extent in forward masking. The suppression of the probe in tuning curves measured in simultaneous masking appears to constrain off‐frequency listening. In forward‐masking tuning curves, off‐frequency listening has a greater effect, and may explain to a large extent the very sharp tuning which has been found in some studies.