The dynamics of indexical information in speech: Can recognizability be controlled by the speaker?

Human voices are individual and humans have elaborate skills in recognizing speakers by their voice, phenomena that are deeply rooted in the evolution of human behavior. To date, the mechanisms of speaker recognition are not well understood because of the high variability of the acoustic cues to a speaker’s identity. We wondered what role the speaker plays in making his/her voice more or less well recognizable. While it is evident from the literature that humans can control vocal properties to enhance their intelligibility, it is unclear whether speakers can and/or do control vocal characteristics to be better recognizable and whether such control mechanisms play a role in the communication process. In this paper, we reviewed results from the literature supporting the view that speaker idiosyncratic information is dynamic and that humans have the ability to control how well they can be recognized. We suggest possible experimental setups by which the control over identity in voice can be tested and present pilot acoustic characteristics of speech that was produced to be either targeted at being (a) intelligible (clear speech) and (b) suitable for person recognition (identity marked speech). Results revealed that there is reason to believe that speakers apply different mechanisms when making their individuality identifiable as opposed to making their speech better understood. We discuss predictions that a control of recognizability and intelligibility has within major theories of speech perception.