Modeling concurrent vowel identification for shorter durations

Abstract

Behavioral studies on concurrent vowels with shorter duration (50 ms) show that overall identification scores across fundamental frequency (F0) differences are reduced when compared to longer duration (200 ms). In this current study, we investigated the effect of shorter durations on concurrent vowel scores using the temporal responses of an auditory-nerve model (Zilany et al., 2014) with a modified version of the Meddis and Hewitt (1992) F0-guided vowel segregation algorithm. The F0 representations of 50 ms vowel pairs were reduced but could not fully account for reduced identification, suggesting a limited ability to avail an F0-guided vowel segregation cue. Thus, by limiting only this cue in the segregation algorithm for 200 ms, the model was qualitatively successful in capturing lower scores across F0 differences for 50 ms. This differential ability to utilize an F0-guided segregation cue might contribute to a variable F0 benefit across normal-hearing listeners. The model also predicted an improvement in identification scores of the second vowel of the pair, when the duration was increased from 50 ms to 200 ms. These model predictions suggest that the inability to utilize an F0-guided segregation cue at shorter durations can account for reduced concurrent vowel identification scores across F0 differences.