Perceptual Learning for Native and Non-native Speech

Revisiting the relationship between implicit racial bias and audiovisual benefit for nonnative-accented speech

Speech intelligibility is improved when the listener can see the talker in addition to hearing their voice. Notably, though, previous work has suggested that this "audiovisual benefit" for nonnative (i.e., foreign-accented) speech is smaller than the benefit for native speech, an effect that may be partially accounted for by listeners' implicit racial biases (Yi et al., 2013, The Journal of the Acoustical Society of America, 134[5], EL387-EL393.). In the present study, we sought to replicate these findings in a significantly larger sample of online participants. In a direct replication of Yi et al. (Experiment 1), we found that audiovisual benefit was indeed smaller for nonnative-accented relative to native-accented speech. However, our results did not support the conclusion that implicit racial biases, as measured with two types of implicit association tasks, were related to these differences in audiovisual benefit for native and nonnative speech. In a second experiment, we addressed a potential confound in the experimental design; to ensure that the difference in audiovisual benefit was caused by a difference in accent rather than a difference in overall intelligibility, we reversed the overall difficulty of each accent condition by presenting them at different signal-to-noise ratios. Even when native speech was presented at a much more difficult intelligibility level than nonnative speech, audiovisual benefit for nonnative speech remained poorer. In light of these findings, we discuss alternative explanations of reduced audiovisual benefit for nonnative speech, as well as methodological considerations for future work examining the intersection of social, cognitive, and linguistic processes.

Impacts of acoustic-phonetic variability on perceptual development for spoken language: A review

This article reviews research on when acoustic-phonetic variability facilitates, inhibits, or does not impact perceptual development for spoken language, to illuminate mechanisms by which variability aids learning of language sound patterns. We first summarize structures and sources of variability. We next present proposed mechanisms to account for how and why variability impacts learning. Finally, we review effects of variability in the domains of speech-sound category and pattern learning; word-form recognition and word learning; and accent processing. Variability can be helpful, harmful, or neutral depending on the learner's age and learning objective. Irrelevant variability can facilitate children's learning, particularly for early learning of words and phonotactic rules. For speech-sound change detection and word-form recognition, children seem either unaffected or impaired by irrelevant variability. At the same time, inclusion of variability in training can aid generalization. Variability between accents may slow learning-but with the longer-term benefits of improved comprehension of multiple accents. By highlighting accent as a form of acoustic-phonetic variability and considering impacts of dialect prestige on children's learning, we hope to contribute to a better understanding of how exposure to multiple accents impacts language development and may have implications for literacy development. This article is categorized under: Linguistics > Language Acquisition Psychology > Language Psychology > Perception and Psychophysics.