Who cares who's talking? The influence of talker gender on how listeners hear speech

Speech perception is challenging because the acoustic input is extremely variable. This variability partially stems from differences in how talkers pronounce words. For example, Voice Onset Time (VOT) is the primary cue that distinguishes /b/ from /p/. Women tend to use longer Voice Onset Times (VOTs) than men. A VOT of 20 msec could thus be a /b/ spoken by a woman and a /p/ spoken by a man. A critical question is how listeners deal with this variability. Previous research shows that listeners use these regularities (e.g., the systematic relationship between gender and VOT) to compensate for variability. For example, listeners adjust their phoneme category boundary based on talker gender. However, it is unclear the exact mechanisms by which talker gender information influences speech processing. Talker gender could influence only later stages of speech processing, like phoneme categorization. Alternatively, talker gender could modulate the earliest stage: acoustic cue encoding. I use event-related potentials, eye-tracking in the visual world paradigm, and electrocorticography to isolate the specific role of talker gender in speech perception. The results show that the auditory system influences the earliest stage of speech perception by allowing cues to be encoded relative to prior expectations about gender and that gender is integrated with acoustic cues during lexical activation. These experiments give insight into how the brain deals effectively with variability during categorization.