USC researcher Christopher Shera receives the American Auditory Society’s 2026 Carhart Award

USC researcher Christopher Shera, PhD, has received the American Auditory Society (AAS)’s 2026 Carhart Award for his decades-long collaborative project on the mammalian cochlea and human frequency selectivity.

Founded in 1972 as the American Audiology Society, the AAS began as an effort to unite the many parties involved in the hearing sciences (e.g., clinical care, basic research, engineering and industry) with the goal of advancing research to improve hearing and balance health care. The Carhart Award honors the memory of Northwestern University Professor Raymond Carhart, known colloquially as the “father of audiology.” Born in 1912, Carhart focused on developing diagnostic criteria for various auditory pathologies and tests to assess auditory dysfunction.

Shera’s award-winning project developed and validated a new noninvasive method for estimating frequency tuning in the human cochlea, or how precisely the ear separates different pitches. The findings challenged long-standing assumptions based on animal models and opened new questions about the evolution of human hearing.

As Shera explained, the cochlea acts as an “acoustic prism, mechanically separating the frequency components of sound so they stimulate different populations of sensory cells in the ear.” In simpler terms, those cells help detect and distinguish sounds within a limited frequency band.

In anesthetized non-human mammals, researchers can directly measure the frequency tuning by recording electrical activity from auditory-nerve fibers connected to those sensory cells. Because those invasive measurements aren’t possible in humans, scientists had long relied on indirect, noninvasive measures and generally assumed human hearing worked much like that of common laboratory animals.

Shera’s new method leverages the fact that healthy cochleae produce sound while listening to sound, generating quiet echoes in response to acoustic stimulation. These sound echoes, known as otoacoustic emissions, can be recorded by placing sensitive, low-noise microphones in the ear canal.

“In obtaining more reliable estimates of cochlear frequency selectivity in humans, we unexpectedly and controversially found that human frequency selectivity is substantially better than that of the common laboratory animals usually taken as models for human hearing,” said Shera, a professor in the USC Caruso Department of Otolayngology – Head and Neck Surgery at the Keck School of Medicine of USC.

That result was unexpected because it challenged the common assumption that animal models provided a close approximation of how sharply the human ear distinguishes pitch. It also has broader implications for understanding the biology and evolution of human hearing.

In February, Shera delivered the Carhart Memorial Lecture at the AAS’s Annual Scientific and Technology Conference. His lecture, titled “Sing, Ear of Charming Echo,” outlined the many unexpected twists and turns in this collaborative project and touched on the new questions it has raised about topics such as the evolution of human hearing.

When asked what advice he would give to early-career researchers in auditory physics, Shera emphasized the value of communication: “Communication is so important in science—whether it be writing papers, presenting at conferences, or constructing grant applications—that I think everyone would benefit by incorporating regular writing time into their weekly if not daily routines. Don’t wait until the experiments are done to start writing about them.”