Federal Project Grant Award Summary

The University of Southern California received a $641,537 Project Grant from the National Institute on Deafness and Other Communication Disorders (NIDCD) under the Research Related to Deafness and Communication Disorders program (CFDA 93.173), awarded May 7, 2026, with completion targeted for April 30, 2031. The research investigates cochlear processing of dynamic sounds—particularly frequency sweeps and amplitude modulations characteristic of speech, music, and vocalizations—through a combination of intracochlear vibrometry, otoacoustic emissions (OAEs), and theoretical modeling conducted in animal models. The project addresses fundamental gaps in understanding how the cochlea encodes temporally varying sounds, as prior research has focused primarily on steady-state tone processing.

The award supports three integrated research aims designed to elucidate the mechanisms underlying perceptual asymmetries in sound processing. Aim 1 examines whether cochlear dispersion (differential frequency propagation speeds) explains why upward and downward frequency sweeps produce distinct perceptions despite physical symmetry. Aim 2 investigates how the speed of cochlear compression shapes responses to rapid amplitude changes, testing whether perceived differences between sound intensity ramps and their time-reversed counterparts arise from non-instantaneous cochlear gain regulation. Aim 3 focuses on broadband stimuli combining frequency and amplitude modulations—features typical of natural sounds—to determine whether cochlear nonlinearities produce vibratory response divergences that could account for observed behavioral asymmetries. These research products will advance fundamental understanding of cochlear signal processing relevant to hearing disorders and communication.