Switched-dominance bilingual speech production: Continuous usage versus early exposure

Abstract

Switched dominance bilinguals (i.e., “heritage speakers,” HS, with L2 rather than L1 dominance) have exhibited native-like heritage language (L1) sound perception (e.g., Korean three-way VOT contrast discrimination by Korean HS; Oh, Jun, Knightly, & Au, 2003) and sound production (e.g., Spanish VOT productions by Spanish HS; Au, Knightly, Jun, & Oh, 2002), but far from native-like proficiency in other aspects of L1 function, including morphosyntax (Montrul, 2010). We investigated whether native-like L1 sound production proficiency extended to heritage language sentence-in-noise intelligibility. We recorded English and Spanish sentences by Spanish HS (SHS) and monolingual English controls (English only). Native listeners of each language transcribed these recordings under easy (-4 dB SNR) and hard (-8 dB SNR) conditions. In easy conditions, SHS English and Spanish intelligibility were not significantly different, yet in hard conditions, SHS English intelligibility was significantly higher than SHS Spanish intelligibility. Furthermore, we observed no differences between SHS English and English-control intelligibility in both conditions. These results suggest for SHS, while early Spanish exposure provided some resistance to heritage language/L1 intelligibility degradation, the absence of continuous Spanish usage impacted intelligibility in severely degraded conditions. In contrast, the absence of early English exposure was entirely overcome by later English dominance.