||In the field of the second language acquisition, a number of studies have investigated the phenomenon of linguistic input to L2 learners in order to determine its role in the process of acquiring a target language. In classroom settings, such input is provided by the L2 teacher speech to nonnative speakers of the second language. Research indicates that teacher talk (TT) directed to L2 learners is characterized by discourse, syntactic, lexical, and phonological modifications. However, only a few studies provide evidence about the effects of TT phonetic/phonological adjustments on the nonnative comprehension. In the present study, nonnative listeners participated in an auditory sentence-final keyword transcription task for teacher talk and conversational speech. Results revealed that NNSs exhibited a significant main effect of speech type, with teacher talk more intelligible than conversational speech. However, the pattern of results in this study showed that the magnitude of speech type benefit differs depending on different levels of various factors such as level of learner proficiency, talker, and sentential context;. The results from this study are interpreted in terms of their implications for providing comprehensible input to L2 learners in order to assist their language acquisition.