Preattentive processing of plosive phonetic detail in Spanish–Basque bilinguals

Bidirectional interactions between first language (L1) and second language (L2) are observed in bilingual speech sound perception. The present study aims to investigate the extent to which perception of phonetically similar sounds within L1 and L2 is influenced by their prototypicality at early stages of auditory processing. Herein, we conducted two auditory oddball experiments using magnetoencephalography in order to investigate the perception of plosives (i.e. /b/ and /p/) in Spanish–Basque bilinguals. We focused on the M100 neural response and the magnetic mismatch negativity component (MMNm), analysing participants’ brain responses using linear mixed-effects modelling. Distinct MMNm responses were observed for within-category /b/ and /p/ sounds, suggesting that the prototypicality of similar sounds is processed at the early stages of bilingual perception.