Masker envelopes and simultaneous‐masking psychophysical tuning curves

Abstract

Recent reports demonstrate that the temporal envelope of a masking stimulus can influence its effectiveness. To examine the probable effects of masker envelope on psychophysical measures of tuning, simultaneous‐masking psychophysical tuning curves (PTCs) were obtained from two normal‐hearing listeners. The probe was a 250‐ms 1‐kHz tone burst presented at 60 dB SPL, which was temporally centered within the 500‐ms maskers. Maskers included SAM and QFM tones, narrow‐band noise, and pure tones. PTCs were obtained in quiet and in the presence of a continuous broadband noise to mask combination tones. Results indicate that fluctuating envelope maskers are less effective than flat envelope maskers only on the low‐frequency side of the PTC. These data suggest that the listener is able to listen for the presence of a probe during periods of low masker energy. Four of the six maskers interacted with the probe producing audible combination tones that could be masked by the broadband noise. Combination tones were most pronounced for the QFM and pure tone maskers, which have similar envelopes. The significance of these data will be discussed in terms of frequency and temporal resolution, particularly with regard to the hearing‐impaired population. [Work supported by NINCDS.]