Neural Bases of Masked Amplitude-Modulation Perception

This project in the Henry lab investigates mechanisms for hearing under real-world listening conditions with fluctuating background noise. Amplitude modulation (AM) is a critical acoustic feature of sound necessary for robust speech perception. Human listeners show reduced AM sensitivity in competing for noise fluctuations of similar frequency, known as modulation masking. Modulation masking is not explainable by classic power-spectrum models but instead suggests a "modulation filterbank" processing strategy that separates concurrent sounds (e.g., AM targets from noise) with different AM frequencies. Physiological mechanisms of the modulation filter bank are crucial to understanding given high relevance to real-world hearing but remain poorly understood due in part to the limited development of animal models. This project in the Henry lab combines behavioral operant conditioning and neurophysiological approaches in an animal model to characterize the neural mechanisms underlying the modulation filter bank and real-world hearing abilities in fluctuating noise more generally.

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