Effects of linguistic experience on brainstem encoding of speech sounds

Abstract

Linguistic experience has been demonstrated repeatedly over the past decades as an important factor influencing the perception of speech sounds. At the behavioral level, speakers of different languages identify and discriminate speech sounds differentially (e.g., categorical perception). This has been observed at the cortical level as a reduced Mismatch Response, a measure that can reflect the sensitivity of the cortex to the differences between sounds. Yet, the effect of linguistic experience at an earlier stage of speech processing, namely, the brainstem, is scarcely studied. In the current study, we therefore aimed to examine specifically whether linguistic experience affects speech sound processing at the brainstem level. Twenty native Spanish speakers and twenty monolingual English speakers are recruited and their brainstem response to speech sounds will be measured with EEG. Specifically, we will use synthesized speech sounds: /ba/ with a + 10 ms and a -40 ms voice-onset-time (VOT). We hypothesize that while the encoding by the two groups will be similar for the + 10 ms /ba/ (common to English and Spanish), English speakers’ encoding of -40 ms prevoiced /ba/s (Spanish only) will be reduced relative to Spanish speakers. Data will be analyzed and interpreted with regards to these hypotheses.