January 3, 2018

Pitch imperfect? How the brain decodes pitch may improve cochlear implants

Picture yourself with a friend in a crowded restaurant. The din of other diners, the clattering of dishes, the muffled notes of background music, the voice of your friend, not to mention your own – all compete for your brain’s attention.

For many people, the brain can automatically distinguish the noises, identifying the sources and recognizing what they “say” and mean thanks to, among other features of sound, pitch.

But for someone who wears a cochlear implant, a surgically implanted electronic device that restores a sense of hearing, pitch is only weakly conveyed. For decades, scientists have debated how, exactly, humans perceive pitch, and how the ear and the brain transmit pitch information in a sound. There are two prevalent theories: place and time. The “time code” theory argues that pitch is a matter of auditory nerve fiber firing rate, while the “place code” theory focuses on where in the inner ear a sound activates.

Now a new study bolsters support for the place code. These findings, published in the September issue of the Journal of Neuroscience, could inform further development of the cochlear implant. The paper’s lead author is Bonnie Lau, a speech-language pathologist and postdoctoral fellow at the University of Washington Institute for Learning & Brain Sciences. Here, her research focuses on development of the human auditory system. Read the full article in UW TODAY.