ASA 125th Meeting Ottawa 1993 May

3aMU2. Identification of a single modulated component in a complex sound.

Brian C. J. Moore

Dept. of Exp. Psychol., Univ. of Cambridge, Downing St., Cambridge CB2 3EB, England

Sid P. Bacon

Arizona State Univ., Tempe, AZ 85287-1908

In experiment 1, subjects were required to decide whether the frequency of a single-modulated carrier (with a suprathreshold modulation depth) in a complex sound was the same as or different from the frequency of a probe composed of a single-modulated carrier. They were able to perform well above chance, i.e., they could identify the modulated carrier. Performance was not greatly affected by whether the probe was presented before or after the complex or by the modulation depth used. Experiment 2 was similar to experiment 1, except that the level of each carrier in the complex was varied randomly from trial to trial. This produced only a very slight impairment of performance, indicating that short-term across-frequency differences in level were not used to identify the modulated component in experiment 1. In both experiments 1 and 2, the identification of a 1000-Hz carrier was best when that carrier was part of a six-carrier harmonic complex, less good when it was part of a six-carrier inharmonic complex, and worst when it was part of a two-carrier complex. The results are interpreted in terms of perceptual grouping. [Work supported by MRC, UK, and NIH.]