Abstract:
In these experiments on spectral-shape discrimination [D. M. Green, Profile Analysis (Oxford U.P., New York, 1988)], the listener's task was to discriminate a standard spectrum in which all components were equal in level, from a signal-plus-standard spectrum in which the level of one component (the signal component) was higher than the level of other components. The threshold was measured as a function of center frequency (250 to 16 000 Hz) for complexes having two or three components. The frequency components were spaced equally on either a logarithmic (f[inf i+1]/f[inf i]=1.38) or linear ((Delta)f=150 Hz) scale. For all the three-component complexes, in which the signal was added to the center component, discrimination was difficult for frequencies above 2 kHz. For the two-component complexes, discrimination was difficult for the logarithmic but not for the linear spacing. In the latter case, a change in spectral shape caused a change in the center of gravity of the stimulus power spectra, which was perceived by listeners as a change in pitch. The availability of the pitch cue made the discrimination possible for the narrowband two-tone complexes at frequencies up to 8 kHz. [Work supported by NIH.]