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Poster A62, Wednesday, November 8, 10:30 – 11:45 am, Harborview and Loch Raven Ballrooms

Speech perception in noise in a native and a second language: A functional magnetic resonance imaging (fMRI) investigation

Shanna Kousaie1,3, Shari Baum2,3, Natalie Phillips3,4,5, Vincent Gracco2,3,6, Debra Titone3,7, Jen-Kai Chen1,3, Xiaoqian J. Chai1, Denise Klein1,3,8;1Neuropsychology/Cognitive Neuroscience Unit, Montreal Neurological Institute, McGill University, Montreal, QC, Canada, 2School of Communication Sciences and Disorders, Faculty of Medicine, McGill University, Montreal, QC, Canada, 3Centre for Research on Brain, Language and Music, McGill University, Montreal, QC, Canada, 4Department of Psychology/Centre for Research in Human Development, Concordia University, Montreal, QC, Canada, 5Bloomfield Centre for Research in Aging, Lady Davis Institute for Medical Research and Jewish General Hospital/McGill University Memory Clinic, Jewish General Hospital, Montreal, QC, Canada, 6Haskins Laboratories, New Haven, CT, USA, 7Department of Psychology, McGill University Montreal, QC, Canada, 8Department of Neurology and Neurosurgery, Faculty of Medicine, McGill University, Montreal, QC, Canada

Language is an important aspect of social human behaviour, with speech processing forming an important part. Given that we are often in sub-optimal listening conditions (e.g., noisy restaurant) it is important to be able to perceive/comprehend speech in noise (SPiN). SPiN can be difficult, and in bilinguals it has been found that SPiN is more difficult in a second (L2) compared to a first language (L1). Previous research has focussed on the use of contextual information in L1 and L2 to support SPiN; however, little research has focussed on SPiN in informationally impoverished situations. We examined SPiN in both languages of highly proficient French/English bilinguals who varied in terms of when they learned their L2, with a focus on SPiN conditions where contextual information was absent. We hypothesized that age of L2 acquisition (AoA) would not impact SPiN in L1; however, in L2 we expected earlier AoA to be associated with better performance and patterns of brain activation suggestive of less effortful processing. Participants were 31 highly proficient French/English bilinguals comprising three groups matched in terms of demographic variables, but varying with respect to when they learned their L2. The groups included simultaneous bilinguals who learned both of their languages from birth (n=10; mean AoA=0 years), early sequential bilinguals who learned their L2 before the age of 6 years (n=13; mean AoA=4.7 years), and late sequential bilinguals who learned their L2 after age 6 (n=8; mean AoA=7.4 years). Participants were presented with sentences where the final word was of high vs. low predictability while they were in the fMRI scanner and were asked to repeat the final word of the sentence. Sentences were presented in English or French and in noise or quiet in a within subjects design. Behaviourally, late sequential bilinguals did not benefit from context in their L2 in noise. fMRI results showed no group differences in the brain regions recruited in L1; however, in L2, the three groups differentially recruited brain regions previously associated with difficult speech processing (i.e., the left inferior frontal gyrus; LIFG) in response to contextually and acoustically impoverished stimuli, with sequential bilinguals showing greater recruitment of this region for high than low predictability stimuli and the opposite pattern in simultaneous bilinguals. Our behavioural results show that SPiN is more effortful in an L2 compared to an L1 and unlike simultaneous and early sequential bilinguals, late sequential bilinguals are not able to benefit from contextual information in their L2. The neuroimaging data show that the LIFG is recruited differentially in an L2 as a function of AoA, with sequential bilinguals showing greater recruitment for high than low predictability stimuli. These findings suggest that early and prolonged exposure to an L2 is advantageous in terms of L2 SPiN processing, with bilinguals who learn their L2 early being better able to make use of contextual information to support SPiN.

Topic Area: Multilingualism

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