Salience of virtual formants as a function of the frequency separation between spectral components

Abstract

The center-of-gravity (COG) hypothesis proposed by Chistovich and others for the perception of static vowels suggests that auditory spectral integration may occur when two or more formants fall within a 3.5 bark bandwidth. While several studies have examined the bandwidth limits of such integration, this study examines the extent to which spectral integration is uniform within this putative 3.5-bark range. We examine the perceptual salience of virtual formants produced by modifying the spectral COG of two closely spaced narrow-bandwidth resonances. Three different vowel series were created: [i-■], [■-■] and [■-■]. A second set of vowels was then created in which one of the formants (F1 in [i-■], F2 in [■-■] and F3 in [■-■]) was replaced by a virtual formant whose COG matched that of the formant that had been removed. The frequency separation between the two component resonances was then systematically varied between 1.5 and 3.5 barks and a singleinterval 2AFC vowel identification task was used to obtain estimates of vowel quality for each series step. Results will be discussed in terms of whether the spectral integration effects within the 3.5 bark decline as the frequency separation between the resonance components increases. [Work supported by NIDCD R01DC00679-01A1.]