Effect of proficiency on perception of English nasal stops by native speakers of Brazilian Portuguese

Abstract

Brazilian Portuguese (BP) does not contrast /m/ and /n/ in coda position, leading to perceptual difficulties with minimal pairs like lime/line in L2 English. This study examined the effect of acoustic-phonetic and semantic enhancements on word recognition in noise for native English (n = 26) and L1 BP/L2 English (n = 21) listeners. They heard 120 high- and low-predictability sentences produced in clear and conversational speaking styles and mixed with speech-shaped noise. They typed the last word ending in either /m/ or /n/. The L2 listeners were separated into high- and low-proficiency (HP and LP) groups based on the perceived accentedness ratings of speech samples they provided. The results showed that native listeners benefited more from semantic than acoustic-phonetic enhancements alone, and the accuracy was highest when both enhancements were combined. The HP L2 listeners recognized more target words overall than the LP group, and their benefit from semantic over acoustic-phonetic enhancements mirrored that of the native listeners. In contrast, LP listeners could not utilize the higher-level semantic information to the same degree in the absence of signal clarity. These findings show that L2 listeners benefited from acoustic-phonetic, semantic, and combined enhancements when recognizing /m/-/n/ coda pairs, but this effect was mediated by proficiency.