Effects of Bilingualism on Speech Recognition Performance in Noise

This study examined the effects of bilingualism on speech recognition in noise performance of young normal-hearing Spanish-English bilinguals across several signal-to-noise ratios (SNR). The estimated signal-to-noise ratio needed for 50% correct recognition performance obtained for bilingual listeners was compared to young normal-hearing monolingual listeners of both English and Spanish. The estimated mean SNR needed for 50% correct recognition was significantly higher (i.e., poorer) for the bilingual than for the monolingual English listeners. The Spanish language performance of the bilingual listeners did not significantly differ from that of the monolingual Spanish listeners. The bilinguals were then divided into subgroups based on age of acquisition of the second language. Bilinguals were subdivided into early and later learners of English and further comparisons were made. The average estimated SNR needed for 50% correct recognition for the early bilinguals did not differ statistically from that of monolingual listeners in either the English or the Spanish language testing. The SNR obtained for 50% correct recognition of English words was significantly higher for the late bilinguals than for the monolingual English listeners. For Spanish words, the mean SNRs obtained for 50% correct recognition for the later bilinguals and the monolingual Spanish speakers did not differ statistically from one another. These results suggest that caution should be used when assessing speech-in-noise performance in the second language of bilingual patients because separate norms may be needed for this population. Age of acquisition of the second language should be considered as a confounding factor in speech-in-noise performance of bilingual listeners