ASA 124th Meeting New Orleans 1992 October

1pPP3. Spectral-shape discrimination of 3-component complexes as a function of the center frequency.

Huanping Dai

David M. Green

Psychoacoust. Lab., Psychol. Dept., Univ. of Florida, Gainesville, FL 32611

Thresholds for profile detection using 3-component complexes were measured at different frequency regions. The frequency ratio of adjacent components was fixed at 1.37. In the standard spectrum, all components were equal in level. In the standard-plus-signal spectrum, the center component was increased in level. The overall level of the standard was randomly selected from the range 45--65 dB SPL on each presentation. Thresholds were estimated using a maximum-likelihood procedure in a two-alternative, forced-choice task. The center frequency of the complex was varied from 250 to 4000 Hz. The results from three observers show that as the center frequency of the complex increases it is more difficult to detect the signal---the threshold at 4000 Hz was nearly 20 dB above that at 250 Hz. Possible explanation for these results are discussed. [Research supported by NIH and AFOSR.]