Speaker Sex Perception from Spontaneous and Volitional Nonverbal Vocalizations.

In two experiments, we explore how speaker sex recognition is affected by vocal flexibility, introduced by volitional and spontaneous vocalizations. In Experiment 1, participants judged speaker sex from two spontaneous vocalizations, laughter and crying, and volitionally produced vowels. Striking effects of speaker sex emerged: For male vocalizations, listeners' performance was significantly impaired for spontaneous vocalizations (laughter and crying) compared to a volitional baseline (repeated vowels), a pattern that was also reflected in longer reaction times for spontaneous vocalizations. Further, performance was less accurate for laughter than crying. For female vocalizations, a different pattern emerged. In Experiment 2, we largely replicated the findings of Experiment 1 using spontaneous laughter, volitional laughter and (volitional) vowels: here, performance for male vocalizations was impaired for spontaneous laughter compared to both volitional laughter and vowels, providing further evidence that differences in volitional control over vocal production may modulate our ability to accurately perceive speaker sex from vocal signals. For both experiments, acoustic analyses showed relationships between stimulus fundamental frequency (F0) and the participants' responses. The higher the F0 of a vocal signal, the more likely listeners were to perceive a vocalization as being produced by a female speaker, an effect that was more pronounced for vocalizations produced by males. We discuss the results in terms of the availability of salient acoustic cues across different vocalizations

Voice processing and voice-identity recognition

The human voice is the most important sound source in our environment, not only because it produces speech, but also because it conveys information about the speaker. In many situations, listeners understand the speech message and recognize the speaker with minimal effort. Psychophysical studies have investigated which voice qualities (such as vocal timbre) distinguish speakers and allow listeners to recognize speakers. Glottal and vocal tract characteristics strongly influence perceived similarity between speakers and serve as cues for voice-identity recognition. However, the importance of a particular voice quality for voice-identity recognition depends on the speaker and the stimulus. Voice-identity recognition relies on a network of brain regions comprising a core system of auditory regions within the temporal lobe (including regions dedicated to processing glottal and vocal tract characteristics and regions that play more abstract roles) and an extended system of nonauditory regions representing information associated with specific voice identities (e.g., faces and names). This brain network is supported by early, direct connections between the core voice system and an analogous core face system. Precisely how all these brain regions work together to accomplish voice-identity recognition remains an open question; answering it will require rigorous testing of hypotheses derived from theoretical accounts of voice processing