FREQUENCY CORRELATION-FUNCTIONS FOR THE DETECTION OF A TONE ADDED TO MODULATED NOISE MASKERS

Psychophysical experiments using reproducible stimuli were completed f or the detection of a 1000-Hz tone added to a masker. The noise masker was either sinusoidally amplitude modulated or not, and masker bandwi dths of 100, 300, and 900 Hz were tested. The masker was centered at 1 000 Hz and the rate of amplitude modulation, when present, was 29 Hz. On average, comodulation masking release values of 10 and 16 dB were o btained 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 o f each spectral component of each stimulus token and the observers' re sponses to that token. The resulting correlation functions estimate th e relative contribution or weight of different frequency regions to th e observers' responses. While the correlation functions for the modula ted and unmodulated maskers share some features, differences in both t he pattern and quality of fit are apparent for wideband maskers. For t wo of the observers, however, restricting the region of comparison to the region surrounding the signal frequency led to increased similarit y of the correlation functions. (C) 1996 Acoustical Society of America .