Summary

The phonetics of emotion is about the acoustic-phonetic properties of the emotional facets of human vocalization. Conventionally, these properties are studied as correlates of a person’s internal states arising from reactions to the environment, where the internal states are defined by influential psychological theories of emotion. A more recent perspective, however, views emotion as an evolved mechanism for motivating actions to proactively interact with other individuals, including, in particular, the production of emotional expressions. From this perspective, the acoustic properties of emotional vocalization are devised to actively influence the listeners in ways that may benefit the vocalizer. Interestingly, the meanings of these acoustic properties could be interpreted with knowledge of speech acoustics accumulated over the years. A key encoding mechanism is body size projection, whereby vocal properties associated with emotions like anger make the vocalizer sound large to dominate the listener, while properties associated with emotions like joy make the vocalizer sound small to appease the listener. Body size projection is encoded through three acoustic dimensions—pitch, voice quality, and formant dispersion. Furthermore, body size projection is likely accompanied by additional iconic encoding mechanisms also aimed at influencing the listener in specific ways. The acoustic properties associated with these mechanisms are not yet fully clear. Further exploration of the body size projection principle and identification of additional mechanisms may drive much of the research activity in the coming decades.