How our own voice influences speech perception

In natural communication, our own speech and that of others follow each other in rapid succession. As such, the immediate context of an utterance spoken by our conversational partner includes speech that we produced ourselves moments earlier. Given the close temporal proximity of our own speech to that of others, it is surprising to find that there are hardly any studies investigating whether and how the phonetic properties of our own speech may influence our perception of the speech of others. In contrast, effects of surrounding context are well known in the literature. For example, the perception of an ambiguous Dutch vowel midway between short /ɑ/ and long /a:/ may be shifted towards the perception of long /a:/ by presenting it in a context sentence with a fast speech rate. This temporal context effect, known as rate normalization, seems to be a general auditory process which generalizes across different sound sources. For instance, listening to a talker with a fast speech rate may influence our perception of another talker (Newman & Sawusch, 2009). This raises the question whether producing slow or fast speech rates ourselves may also influence our perception of others. This study investigated effects of our own speech rate on our perception of others through a set of experiments targeting rate normalization. In each experiment, fast and slow context sentences were followed by target words containing a vowel continuum from /ɑ/ to /a:/. Experiment 1 used a standard rate normalization design, with participants listening to fast and slow speech followed by ambiguous target words. The categorization patterns of target words, observed in Experiment 1, replicate previous studies showing that hearing a fast speech rate biases subsequent target perception towards /a:/. In Experiment 2, participants were instructed to produce the context sentences themselves at a specified fast or slow rate, after which the ambiguous target words were immediately presented auditorily. Participants’ categorization data show that the faster participants produced the context sentences, the more they reported to perceive the target vowel /a:/. That is, participants’ own speech rate influenced their perception of subsequent target words. This suggests that phonetic properties of our own voice can change our perception of others (through normalization for one’s own speech rate). Experiment 3 tested whether covert speech production (i.e., silent production in one’s mind) at different rates may also influence subsequent perception. However, this time no effect of the covertly produced fast and slow rates was observed. Together, Experiment 2 and Experiment 3 suggest a central role for self-monitoring of the external (i.e., overt) speech signal. Concluding, this study finds that variation in speech production may induce variation in speech perception, thus carrying implications for our understanding of spoken communication in common dialogue settings. Moreover, it may provide a novel rationale for phonetic convergence in conversation (when two interlocutors converge towards each other’s speech rate). That is, phonetic convergence may not only be beneficial for social integration but also help to avoid interfering effects of (self-produced) divergent speech rates