| The language we hear around us daily is usually presented in less-than-ideal conditions. As native speakers of a language, most of us can navigate this task with some success, although we still have trouble. It is even more difficult for a second language (L2) learner. For language learners, it is important to understand what factors influence how well they understand speech when they hear it in noise.;Based on previous studies of first language (L1) sentence recognition in noise, I propose a model of L2 sentence recognition in noise. Given evidence for executive functions' (EF) influence on L1 sentence recognition, it seems plausible that similar EF factors would affect L2 sentence recognition. L2 proficiency and vocabulary have been shown to influence L2 sentence recognition in noise (Shi, 2012; Shi & Farooq, 2012). L1 sentence recognition may also be expected to correlate with L2 sentence recognition. It logically follows that if one has trouble with L1 speech perception in noise, they will subsequently have difficulty in their L2.;This dissertation investigated the neurocognitive, linguistic, and L1 factors affecting L2 sentence recognition in quiet and noise. It was found that predictors of L2 speech perception differed by learner level. For intermediate learners, L2 sentence recognition in noise was predicted by attention/inhibition and reading comprehension. For advanced learners, L2 proficiency and two L1 measures (L1 sentence recognition in noise, English vocabulary) predicted L2 speech perception in noise. When both groups were combined, only L2 proficiency measures predicted L2 speech perception in noise. Thus, it is important to separate learner levels to more clearly demonstrate the predictors of L2 speech perception.;A new group of participants completed an fMRI experiment in which they heard L1/L2 sentences in quiet and in noise during scanning. It was found that recognizing sentences in noise in the L1 and L2 activated both perceptual and attention regions. For L2 speech in noise, listeners used bottom-up processing; they focused on phonetic detail in the signal. For L1 speech in noise, listeners used top-down processing, focusing on lexical retrieval to fill in gaps for sentence recognition. |
