Non-native clear speech increases intelligibility but not through improved word segmentation: Evidence from a visual-world eye-tracking study

Listener-directed hyperarticulated clear speech produced by native (L1) talkers improves word segmentation and reduces lexical competition. Less is known about whether non-native (L2) clear speech also confers such benefit. In a visual-world eye-tracking study, we investigated if L2 clear speech improves word segmentation and the time course of the benefit for native listeners. Forty L1 English participants heard sentences produced in conversational and clear styles by a highly intelligible L2 English / L1 Spanish speaker with a discernable non-native accent. Sentences contained a target word (e.g., doll) with which a corresponding competitor overlapped phonemically (e.g., dolphin), creating temporary ambiguity with the target and the following word’s onset (e.g., doll found). Each recording was presented in quiet alongside pictures of the target, competitor, and two distractors. Participants were instructed to select the picture mentioned in the sentence they heard. No significant clear speech segmentation advantage was found; the proportion of looks to targets over competitors indicates similar time course of disambiguation in both conversational and clear speech. The results suggest that L2-accented clear speech with its deviations from the target-language- specific modifications and greater phonetic variability increases signal uncertainty resulting in no benefit for word segmentation even though word recognition was improved.