John R. Carter
Patrick W. Rappold
Dept. of Speech Pathol. and Audiol., Univ. of South Alabama, Mobile, AL 36688
Madhuri S. Muelkar
Univ. of South Alabama, Mobile, AL 36688
The effects of incremental changes in degree of temporal envelope correlation on the auditory fusion of narrow-band noise (NBN) pairs were examined by placing fusion in competition with sequential streaming for one component of a NBN pair. Seven levels of envelope correlation were represented (r=1.0, 0.75, 0.50, 0.25, 0.00, -0.25, -0.35) by three sets of NBN pairs, for a total of 21 NBN pairs. A NBN pair consisted of a target band spectrally centered at 2000 Hz, and a flanker band centered at 1500 Hz. A NBN pair was played alternately with the target band alone (captor band) at an initial interstimulus interval (ISI) of 500 ms. The ISI decreased automatically in 5- or 2-ms increments until a subject exited the program when judging the perceptual prominence of sequential streaming as greater than that of fusion. The ISI at exit was used to infer strength of fusion for the NBN pair. Shorter ISIs suggested stronger fusion; longer ISIs suggested weaker fusion. Results showed a trend for ISI to increase with a decrease in the degree of envelope correlation, which suggested a gradual decline in fusion strength as envelope correlation was incremented downward from perfect correlation.