Speech perception in noise by monolingual, bilingual and trilingual listeners

Background: There is strong evidence that bilinguals have a deficit in speech perception for their second language compared with monolingual speakers under unfavourable listening conditions (e. g., noise or reverberation), despite performing similarly to monolingual speakers under quiet conditions. This deficit persists for speakers highly proficient in their second language and is greater in those who learned the language later in life. These findings have important educational implications because the number of multilingual children is increasing worldwide, and many of these children are being taught in their non-native language under poor classroom acoustic conditions. Aims: The performance of monolingual, bilingual and trilingual speakers on an English speech perception task was examined in both quiet and noisy conditions. Trilingual performance was compared with that of monolingual and bilingual speakers. Methods & Procedures: Monolingual speakers of English and early bilingual and trilingual speakers (i.e., acquired English as a second/third language before the age of 6 years) were recruited. Their fluency in English was tested by interview and by a questionnaire assessing their knowledge and use of the language. Audiological evaluation confirmed normal hearing in all participants. English speech perception was tested in quiet and in different levels of noise (50, 55, 60, 65 and 70 dB SPL) using the Speech Perception in Noise (SPIN) Test. Outcomes & Results: Bilingual and trilingual listeners performed similarly to monolingual listeners in quiet conditions, but their performance declined more rapidly in noise and was significantly poorer at 65 and 70 dB SPL. Trilingual listeners performed less well than bilinguals at these noise levels, but not significantly so. A subgroup of five bilingual speakers who learned Arabic and English simultaneously since birth were poorer at higher levels of noise than monolinguals, but not significantly so. Conclusions & Implications: The results replicate previous findings of poorer speech perception in noise with bilingual speakers compared with monolinguals and extend the findings to trilingual speakers.