The social life of voices: studying the neural bases for the expression and perception of the self and others during spoken communication.

Abstract

In 2013, London Underground reinstated the actor Oswald Laurence's famous “Mind the gap” announcement at Embankment station, having learned that the widow of the actor had been regularly visiting this station since her husband's death in order to hear his voice again (Hope, 2013). Even in the absence of a personal connection to the couple, it is easy to find this an emotionally affecting story. Anecdotally, “It's so nice to hear your voice” is commonly encountered in telephone conversations with loved ones, yet there is relatively little known about the cognitive and neural underpinnings of this expression. Similarly, a sense of ownership of one's voice has important implications—companies like VocalID (www.vocalid.co) have recognized the impact of providing individualized voices to patients who rely upon synthesizers for communication—but, to date, the neuroscience of speech production has been predominantly concerned with the accurate formulation of linguistic messages. Although there are relatively unchanging aspects of every voice, due to the anatomical constraints of the talker's vocal tract as well as body size and shape (Kreiman and Sidtis, 2011), it is also important to note that the voice is not a static object. There is no such thing as a passive voice; the voice (like all sounds) demands an action to occur for it to exist at all (Scott and McGettigan, 2015). Much of our vocal expression is the result of voluntary motor acts, which can be modified consciously in response to changes in acoustic, informational and social demands (McGettigan and Scott, 2014; Scott and McGettigan, 2015). Sidtis and Kreiman (2012) write that the voice is “revelatory of ‘self,’ mental states, and consciousness,” reflecting “both the speaker and the context in which the voice is produced” (p. 150). It is thus a dynamic self that is modified according to the talker's goals, affecting both the talker and the addressee in their roles as perceivers and producers of verbal and non-verbal vocal signals. Disruption to paralinguistic aspects of voice perception and production has implications for psychosocial wellbeing. Most reports of Foreign Accent Syndrome—where patients produce altered speech that perceptually resembles a non-native accent (e.g., due to brain injury, or orofacial surgery)—concentrate on the phonetic, perceptual and neurological correlates of the disorder, yet there is evidence that there can also be significant impacts on the patient's sense of self-identity (Miller et al., 2011; DiLollo et al., 2014). In voice perception, difficulties in the recognition of emotional and attitudinal prosody have implications for effective psychosocial function in healthy aging, schizophrenia, and autism (Mitchell and Ross, 2013). It is thus crucial that neurobiological accounts of speech and voice processing consider not just what is said, but how it is said, in order to characterize the human aspects of vocal communication behaviors.