Recognition of foreign-accented speech in noise: The interplay between talker intelligibility and linguistic structure

Foreign-accented speech recognition is typically tested with linguistically simple materials, which offer a limited window into realistic speech processing. The present study examined the relationship between linguistic structure and talker intelligibility in several sentence-in-noise recognition experiments. Listeners transcribed simple/short and more complex/longer sentences embedded in noise. The sentences were spoken by three talkers of varying intelligibility: one native, one high-, and one low-intelligibility non-native English speakers. The effect of linguistic structure on sentence recognition accuracy was modulated by talker intelligibility. Accuracy was disadvantaged by increasing complexity only for the native and high intelligibility foreign-accented talkers, whereas no such effect was found for the low intelligibility foreign-accented talker. This pattern emerged across conditions: low and high signal-to-noise ratios, mixed and blocked stimulus presentation, and in the absence of a major cue to prosodic structure, the natural pitch contour of the sentences. Moreover, the pattern generalized to a different set of three talkers that matched the intelligibility of the original talkers. Taken together, the results in this study suggest that listeners employ qualitatively different speech processing strategies for low-versus high-intelligibility foreign-accented talkers, with sentence-related linguistic factors only emerging for speech over a threshold of intelligibility. Findings are discussed in the context of alternative accounts.