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Linking phonetic plasticity to intersubject neural synchronization during naturalistic speech comprehension
Poster Session A, Wednesday, September 30, 11:00 am - 1:00 pm, Wangari Maathai
This poster is part of the Sandbox Series.
Andrew Collins1, Chris C. Heffner2, Kaila Cote1, Emily Myers1; 1University of Connecticut, 2University at Buffalo
Listeners differ substantially in their ability to adapt to systematic differences in their native language (e.g., accent or talker differences) and their ability to learn novel speech categories in a non-native language. Prior research (Heffner & Myers, 2021) has demonstrated that individuals’ performance in native speech perception and non-native learning pattern together, suggesting that both types of learning are served by a shared underlying capacity termed “phonetic plasticity”. However, while phonetic plasticity has begun to be characterized behaviorally, less is known about how individual differences are reflected in neural responses during continuous, naturalistic speech comprehension. Examining group-level neural synchronization during ecologically valid language processing and identifying individuals’ deviations from the group may lead to a better understanding of how adaptive speech processing mechanisms support real- world speech comprehension. The present study aims to use intersubject correlation (ISC) analyses of fMRI data collected while participants listened to speech to investigate whether individual differences in phonetic plasticity correlate with variability in neural alignment across listeners. Individuals with a higher level of phonetic plasticity may exhibit greater neural synchronization during speech processing due to more efficient adaptation to variable acoustic-phonetic input and more optimal deployment of top-down strategies. Alternatively, greater phonetic plasticity may support more individualized processing strategies, resulting in reduced synchronization across listeners despite successful comprehension. Finally, regional differences in the relationship between inter-subject alignment and phonetic plasticity may be helpful in informing whether differences in phonetic skill are related to bottom-up vs. top-down processing strategies. Identifying and characterizing these competing possibilities may help clarify how adaptive speech processing mechanisms are instantiated during real-time language comprehension. Data were drawn from Heffner & Myers (2021) in which a group of healthy young adults (N = 80) with no history of speech, language, neurological, or hearing deficits tasks to measure native language speech adaptation, non-native learning, and a cognitive battery. All participants additionally underwent structural and functional MRI acquisition, including a podcast listening paradigm in which participants listened to the same 10 minutes of naturalistic speech from a podcast. Functional MRI data from the podcast listening task were subsequently analyzed using intersubject correlation (ISC) methods to assess neural synchronization across listeners during continuous speech comprehension. ISC measures were then related to participant-level phonetic plasticity scores to examine whether individual differences in adaptive speech processing correlate with variability in neural alignment during naturalistic language processing. By linking behavioral measures of phonetic plasticity to intersubject neural synchronization during naturalistic speech comprehension, the present study aims to clarify how adaptive speech processing mechanisms support real-world language use. Additionally, identifying the neurobiological correlates of individual differences in phonetic plasticity may be a critical step in improving outcomes for clinical populations in contexts requiring adaptation to speech input, as learning occurs across the lifespan, and people often interact with others who have different accents or rates of speech.
Topic Areas: Speech Perception,