Semiotic aspects of human nonverbal vocalizations: a functional imaging study.

Humans produce a variety of distinct nonverbal vocalizations. Whereas affective bursts, for example, laughter, have an intrinsic communicative role bound to social behavior, vegetative sounds, for example, snoring, just signal autonomic-physiological states. However, the latter events, for example, belching, may also be used as intentional communicative actions (vocal gestures), characterized by an arbitrary culture-dependent sound-to-meaning (semiotic) relationship, comparable to verbal utterances. Using a decision task, hemodynamic responses to affective bursts, vegetative sounds, and vocal gestures were measured by means of functional magnetic resonance imaging. Affective bursts elicited activation of anterior left superior temporal gyrus. In contrast, arbitrary vocal gestures yielded hemodynamic reactions of the left temporo-parietal junction. Conceivably, a listener's interpretation of nonverbal utterances as intentional events depends upon a left-hemisphere temporo-parietal 'auditory-to-meaning interface' related to our mechanisms of speech processing.