Shortly before his death in August 2025, A. James Hudspeth and his colleagues at The Rockefeller University’s Laboratory of Sensory Neuroscience accomplished a milestone that had never been reached before. They succeeded in keeping a small section of the cochlea alive and working outside the body, making it possible to study the organ’s function directly for the first time. Using a specially designed device, the team was able to track the cochlea’s extraordinary abilities in real time, including its fine-tuned sensitivity, precise frequency detection, and capacity to process a wide range of sound levels.

“We can now observe the first steps of the hearing process in a controlled way that was previously impossible,” says co-first author Francesco Gianoli, a postdoctoral fellow in the Hudspeth lab.

The achievement, detailed in two recent publications (in PNAS and Hearing Research, respectively), represents the culmination of Hudspeth’s fifty years of pioneering research into the cellular and neural basis of hearing. His work has continually pointed toward new possibilities for preventing and treating hearing loss.

Beyond its immediate applications, the advance also delivers long-sought experimental confirmation of a fundamental biophysical principle that underlies hearing across diverse species, a concept Hudspeth had pursued for more than twenty-five years.

“This study is a masterpiece,” says biophysicist Marcelo Magnasco, head of the Laboratory of Integrative Neuroscience at Rockefeller, who collaborated with Hudspeth on some of his seminal findings. “In the field of biophysics, it’s one of the most impressive experiments of the last five years.”

The mechanics of hearing
Though the cochlea is a marvel of evolutionary engineering, some of its fundamental mechanisms have long remained hidden. The organ’s fragility and inaccessibility—embedded as it is in the densest bone in the body—have made it difficult to study in action.

These challenges have long frustrated hearing researchers, because most hearing loss results from damage to sensory receptors called hair cells that line the cochlea. The organ has some 16,000 of these hair cells, so-called because each one is topped by a few hundred fine “feelers,” or stereocilia, that early microscopists likened to hair. Each bundle is a tuned machine that amplifies and converts sound vibrations into electrical responses that the brain can then interpret.