Karolina Charaziak, PhD, an assistant professor in the USC Caruso Department of Otolaryngology – Head and Neck Surgery at the Keck School of Medicine of USC, received a $3.3 million National Institutes of Health (NIH) Research Project (R01) grant on July 7, 2026. The grant, funded by the NIH's National Institute on Deafness and Other Communication Disorders (NIDCD), will support a five-year study into how the cochlea processes complex sounds in both healthy hearing and hearing loss.

The research will combine advanced cochlear imaging, electrical recordings, and computational modeling. The project will investigate how nonlinearity and dispersion shape the way people hear speech, music, and other complex sounds. "In simple terms, the first property, nonlinearity, refers to the cochlea's ability to actively amplify soft sounds while compressing louder ones," Charaziak said. "The second property, dispersion, refers to the fact that different frequencies travel through the cochlea at different speeds." The research team will pair direct measurements from lab animals with noninvasive hearing measurements.

Charaziak's lab previously developed objective, noninvasive measures of cochlear function in mice with hearing loss. The lab demonstrated that tiny electrical signals generated by sensory cells in the inner ear can reveal how well the cochlea amplifies and compresses sound. These preliminary findings were presented at the Association for Research in Otolaryngology (ARO) meeting. The cochlea is the part of the inner ear responsible for hearing.

"Many patients experience hearing difficulties that are not fully explained by a standard hearing test," Charaziak said. "Current clinical measures provide only a limited view of cochlear health and often cannot identify which specific structures within the inner ear are malfunctioning."

Why It Matters

"In the long term, these advances could improve diagnosis, help clinicians distinguish among different forms of sensory hearing loss and potentially guide more personalized treatment strategies," Charaziak said. "The work may also inform the design of hearing aids, cochlear implants and signal-processing algorithms by providing a more accurate understanding of how the healthy cochlea encodes speech and other complex sounds."