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The role of nonlinearity and dispersion in spatiotemporal processing in the cochlea

Award Number: R01DC022942
ORGANIZATION: NATIONAL INSTITUTE ON DEAFNESS AND OTHER COMMUNICATION DISORDERS
OPDIV: NIH
AWARD CLASS: DISCRETIONARY
AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)
PERIOD OF PERFORMANCE START DATE: 05/07/2026
PERIOD OF PERFORMANCE END DATE: 04/30/2031

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The role of nonlinearity and dispersion in spatiotemporal processing in the cochlea - PROJECT SUMMARY Human communication relies on speech sounds that exhibit complex spectral and temporal patterns, which must be faithfully encoded by the cochlea—the sensory organ of hearing. While cochlear function has been exten- sively studied using steady-state tones, much less is known about how the cochlea processes dynamic sounds that vary over time, such as frequency and intensity modulations common in speech, music, and vocalizations. This research aims to address this gap by combining intracochlear vibrometry, otoacoustic emissions (OAEs), and theoretical modeling to investigate cochlear processing of dynamic sounds in animal models. Aim 1 examines the role of cochlear dispersion—where different frequencies propagate at different speeds— in processing of frequency sweeps, where instantaneous frequency decreases or increases over time. Although upward and downward sweeps are physically symmetric (i.e., time-reversed with identical spectra), they elicit distinct percepts. We will test whether this perceptual asymmetry arises from differences in cochlear vibratory responses due to traveling wave dispersion. Aim 2 investigates how the speed of cochlear compression shapes responses to rapid amplitude changes. Sounds that gradually increase in amplitude (upramp) are perceived as louder and more effective maskers than their time-reversed copies (downramp), despite having the same energy. We will manipulate the rate and direction of amplitude changes to test the hypothesis that these perceptual temporal asymmetries could arise from non-instantaneous regulation of cochlear gain. Aim 3 focuses on broadband stimuli that combine frequency and amplitude modulations (moving ripple)—features typical of natural sounds. These stimuli allow precise control of spatiotemporal structure, enabling us to test whether cochlear nonlinearities and asymmetries produce vibratory responses that diverge from predictions made by simplified models. Across all aims, we will study both normal-hearing and hearing-impaired animals to understand how sensory loss alters dynamic sound processing. Whenever feasible, we will combine vibrometry with OAEs to assess the extent to which OAEs serve as noninvasive proxies for cochlear dynamics. Finally, we use cochlear models both to test mechanistic hypotheses—by independently varying tuning, gain, and dispersion—and to assess their predictive power across stimuli and species. This dual role provides critical insight into cochlear processing and supports future applications in hearing technologies, where accurate simulation of cochlear output is essential for improving signal processing algorithms. This project will deliver the first systematic investigation of cochlear responses to dynamic sounds with real-world relevance. By correlating OAEs with mechanical data, it aims to validate OAEs as clinically useful, noninvasive markers of cochlear function. These insights will advance our understanding of temporal hearing and how it degrades with sensory loss.


Issue Date FY	Funding FY	Legal Entity Name	Legal Entity Address	Legal Entity City	Legal Entity State	Legal Entity Zip Code	Legal Entity COUNTY	Legal Entity COUNTRY	Assistance Listing	Award Code	Budget Year	Action Date	Action Type	Action Amount

Issue Date FY: 2026 ( Subtotal = $641,537 )
2026	2026	UNIVERSITY OF SOUTHERN CALIFORNIA	3720 S FLOWER ST FL 3	LOS ANGELES	CA	90033	LOS ANGELES	USA	Research Related to Deafness and Communication Disorders	000	1	5/12/2026	NEW	$641,537
														Subtotal = $641,537

Grand Total All Awards = $641,537

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The role of nonlinearity and dispersion in spatiotemporal processing in the cochlea

Award Number: R01DC022942

ORGANIZATION: NATIONAL INSTITUTE ON DEAFNESS AND OTHER COMMUNICATION DISORDERS

OPDIV: NIH

AWARD CLASS: DISCRETIONARY

AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)

PERIOD OF PERFORMANCE START DATE: 05/07/2026

PERIOD OF PERFORMANCE END DATE: 04/30/2031

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