Suprathreshold perception under a masking release condition using categorical scaling

Abstract

Masking experiments provide important information on how the auditory system processes sounds. For example, a tone is less masked by a modulated sound than by an unmodulated sound with the same long-term spectrum, indicating the ability of the auditory system to use modulation as a cue. In general, studies on this modulated-unmodulated difference (MUD) focus on the thresholds, whereas little is known about suprathreshold perception under these conditions of masking release. In the present study, loudness growth functions of a masked 1000-Hz tone are measured for two different masker types: (i) amplitude modulated broadband noise with a square-wave modulator and (ii) an unmodulated noise with the same spectral content and level. A categorical loudness scaling procedure (ISO 16832) is used to measure loudness of the masked tone over a large level range. The accuracy of the procedure is quantified by comparing the scaling results with loudness matching data for the same masker types. It is investigated (i) up to which suprathreshold level a masking release is still observed and (ii) whether the effect of the reduced masking for the modulated masker is equivalent to a condition where the unmodulated masker is reduced in level by the magnitude of the MUD.