Salience of dynamic virtual formants in diphthongs

Abstract

Variations in the quality of a synthesized vowel can be produced by changing the frequency of its steady-state formants or the amplitude of closely-spaced static spectral components—the latter effect a function of auditory spectral integration. Recent studies have demonstrated that dynamic modification of the amplitude ratios of these spectral components can give rise to the perception of virtual diphthongs. This study examines the extent to which spectral integration of these dynamic components is uniform across a range of frequency separations of these spectral components (previous work [Fox et al., ‘‘Title,’’ J. Acoust. Soc. Am. 120, 3252 (2006)] demonstrated the integration of static components beyond 3.5 bark). Two synthetic vowel series were created by modifying the rise or fall of F2 producing [■i]-[■:]-[■u] and [i■]-[■:]-[u■] series. Next, several different series were created in which this dynamic F2 was replaced by two static spectral components whose amplitude ratios were varied over time (virtual F2 glides). The spectral separation of these two components varied from 2.0 to 4.0 bark. A single-interval 2AFC identification task was used to obtain estimates of vowel quality. Results will be discussed in terms of whether the spectral integration effects decline as the frequency separation between components increases. [Work supported by NIDCD R01DC00679-01A1.]