Training listeners to report the acoustic correlate of formant-frequency scaling using synthetic voices

The vocal tract length of a speaker is the primary determinant of the range of formant frequencies (FFs) produced by that speaker. Listeners have demonstrated sensitivity to the average FFs produced by voices, for example, in estimating the relative heights of two speakers based on their speech. However, it is not known whether they can learn to identify voices based on the acoustic characteristic associated with the average FFs produced by a voice (this characteristic will be referred to as FF-scaling). To investigate this, a series of vowels corresponding to voices that differed in their average f0 and/or FF-scaling were synthesized. Listeners (n = 71) were trained to identify these voices using a training procedure where, for each trial, they heard the vowels representing a voice and then had to identify the stimulus voice from among a series of candidate voices that differed in terms of their FF-scaling and/or their f0. Results indicate that listeners can identify voices on the basis of FF-scaling quite accurately and consistently after only a short training session and that, although f0 weakly influences these estimates, they are most strongly determined by the stimulus FFs.