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Poster C68, Wednesday, August 21, 2019, 10:45 am – 12:30 pm, Restaurant Hall

Structural neural correlates of native-language speech perception and non-native speech sound learning

Pamela Fuhrmeister1, Emily Myers1,2;1University of Connecticut, 2Haskins Laboratories

Individuals show a wide range of variability in how well they learn non-native speech sounds, but the cognitive and neural sources of this variability are poorly understood. Individual differences in native-language category representations may be one source of variability in non-native speech sound learning. Specifically, individuals vary in how categorically or graded they perceive sounds in their native language (e.g., Kapnoula et al., 2017; Kong & Edwards, 2016), but the relationship between native-language speech perception and non-native speech sound learning has not yet been tested. Just as the behavioral connections between native and non-native speech processing are unknown, it is not yet known whether individual differences in brain structure relate to native as well as non-native speech sound perception. Structural differences in brain morphology (for example, in early auditory areas) have been shown to be related to success on non-native speech sound learning tasks (Golestani et al., 2002, 2007; Turker et al., 2017). However, for native-language speech perception, no work has yet established the structural differences that underlie variation in performance. The current study seeks to identify whether structural differences in a common area underlie behavioral differences in native and non-native speech processing. To test this, native English-speaking participants rated speech sounds from two different native contrasts (stop and fricative continua) on a scale to measure individual differences in native language sound processing. Participants additionally learned to categorize a non-native contrast (Hindi voiced dental and retroflex stops) and completed assessments of their learning in the evening hours and returned the next morning for reassessment. Anatomical images were collected at a separate session. Results suggest no strong behavioral relationships between native-language speech perception and non-native speech sound learning. However, surface area and gray matter volume of the left transverse temporal gyrus positively predicted learning on the Hindi task in both the immediate and next-day assessments, and surface area of the pars opercularis region of the left inferior frontal gyrus was negatively correlated with non-native speech sound learning. In addition, volume of the left hippocampus was positively related to overnight change in the non-native speech sound learning task. These findings are consistent with the view that individual differences in auditory cortex morphology support the perception of difficult non-native speech contrasts.

Themes: Speech Perception, Multilingualism
Method: Other

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