Frequency correlation functions for the detection of a tone added to modulated noise maskers.

Abstract

Psychophysical experiments using reproducible stimuli were completed for the detection of a 1000-Hz tone added to a masker. The noise masker was either sinusoidally amplitude modulated or not, and masker bandwidths of 100, 300, and 900 Hz were tested. The masker was centered at 1000 Hz and the rate of amplitude modulation, when present, was 29 Hz. On average, comodulation masking release values of 10 and 16 dB were obtained for the 300- and 900-Hz-wide maskers, respectively. No release from masking was obtained for the 100-Hz-wide maskers. Data analysis consisted of computing the correlation coefficient between the level of each spectral component of each stimulus token and the observers’ responses to that token. The resulting correlation functions estimate the relative contribution or weight of different frequency regions to the observers’ responses. While the correlation functions for the modulated and unmodulated maskers share some features, differences in both the pattern and quality of fit are apparent for wideband maskers. For two of the observers, however, restricting the region of comparison to the region surrounding the signal frequency led to increased similarity of the correlation functions.