He decided that he could help bridge that gap and, as a postdoctoral fellow at the Karolinska Hospital in Stockholm, began to study the mechanisms of hearing. Upon his return to the United States, he narrowed his work even further in his studies of the inner ear, which began at the California Institute of Technology. His first challenge was to find a way to study the inner ear outside its well-protected site in the head. His answer lay in the fact that the amphibian ear is structurally similar to the mammalian ear but easier to access. How It Works Vibrations pass from the outside world through a series of bony structures to the cochlea, a coiled tube that senses the various frequencies present and passes this information to the brain.
Hair cells populate the length of the cochlea down the basilar membrane.
Pitch perception is thus encoded in the position along the basilar membrane of the hair cells that are the most strongly stimulated. Dr. Hudspeth developed methods to remove living hair cells from frogs and record the electrical changes that occur when their stereocilia are tickled with a vibrating probe. The new technique enabled Dr. Hudspeth and his research team to confirm that the stereocilia are in fact the hair cell's sensory organelles. They also found that displacing the stereocilia, even by the diameter of an atom, causes a change in voltage in the hair cell. Still, the molecular mechanism that opened the ion channels remained unclear to researchers.