Dual language learning as a training ground for sensory processing

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Sound is an important part of the human experience and the ability to perceive sonic intricacies can have a large impact on the quality of life, especially later in life when hearing in noisy environments becomes more challenging. There is growing public and scientific interest in finding ways to improve auditory processing to overcome these challenges. Similar to musical training, speaking two languages has been proposed as a naturalistic training ground for benefiting auditory processing. Yet despite the worldwide prevalence of bilingualism, little is known about how the structure and function of the central auditory system are impacted by bilingualism. This research has implications for an ever-growing segment of the U.S. population who speak more than one language. This work also has the potential to advance scientific knowledge by providing the first data on how bilingualism interacts with the aging auditory system. Through education and outreach events, findings will inform practice in real-world educational and clinical contexts. This project will test the hypothesis that bilingualism alters the structure and function of auditory centers as a result of the increased role that sound plays in learning and communicating in two languages. Functional and structural plasticity in bilinguals is predicted to benefit auditory perception of both trained (language) and untrained (non-linguistic) stimuli and promote healthy auditory system aging by decreasing age-related functional declines. In a large sample of young and middle-aged adults (n=200), the project will use magnetic resonance imaging (MRI) to measure auditory neural structure, frequency-following responses (FFRs) to measure auditory function, and psychoacoustic tests to measure detection thresholds for speech and non-speech stimuli (e.g., tones in noise). The dataset will focus on bilinguals who learned their second language from an early age. Among bilinguals, the extent of the structural and functional plasticity is predicted to reflect individual variations in bilingual experience, including the degree of dual language proficiency, use, and exposure. Thus, following recent trends, bilingualism is not treated as a monolithic variable with uniform properties across individuals but instead, it is regarded as a spectrum of experiences and abilities. Preliminary studies supporting the hypothesis have been conducted on small populations using limited stimulus sets; however, an integrated, large-scale study has not been conducted. This research aims to fill this gap.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.