3aPP5. Effect of perceptually separating spectral components on profile discrimination.

Session: Wednesday Morning, December 4

Time: 9:05

Author: Huanping Dai
Location: Boys Town Natl. Res. Hospital, 555 N. 30th St., Omaha, NE 68131


In spectral-shape discrimination [D. M. Green, Profile Analysis (Oxford U.P., Oxford, UK, 1988)], listeners discriminate a standard spectrum in which all components are equal in level, from a signal-plus-standard spectrum in which the level of one component (the signal component) is higher than the level of other nonsignal components. Because the overall level is randomly selected from a wide range of values on each stimulus presentation, the absolute level of the signal component is not a reliable cue for discrimination. Instead, listeners must make a relative level comparison between the signal and nonsignal components. Under normal conditions of profile experiments, listeners can detect signal increments as small as 1 dB. To be discussed here are special cases where the signal component is perceived as a separate sound from the nonsignal components. Perceptual separation between the signal and nonsignal components was achieved by introducing asynchrony in their onsets and offsets, by modulating them differently, or by presenting them in separate ears. Experimental results showed that such separation made spectral-shape discrimination very difficult. Thus optimum performance requires that the signal and nonsignal components be perceived as belonging to a single auditory object. [Work supported by NIH.]

ASA 132nd meeting - Hawaii, December 1996