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Study reveals how the inner ear discerns low-frequency sound

First-of-its-kind discovery at OHSU and Linköping University could result in improving the design of cochlear implants
A computer-illustrated image of sound vibrating through the air and into an ear and inner ear parts. An Oregon Hearing Research study could improve cochlear implants.
The cochlea, in the inner ear, detects low-frequency sound differently than previously known, according to research scientists at Oregon Health & Science University and Linköping University in Sweden. (Getty Images)

Scientists have discovered the cochlea in the inner ear detects low-frequency sound in a manner very different than previously known, according to new research from scientists at Oregon Health & Science University and Linköping University in Sweden.

The finding, published today in the journal Science Advances, may make it possible to design better cochlear implants for people with hearing impairments.

George Burwood, Ph.D., stands out on the OHSU lawn with the OHSU Hospital in background.  (OHSU)
George Burwood, Ph.D. (OHSU)

“It was an astounding moment when we first recognized this finding,” said co-author George Burwood, Ph.D., research instructor in the Oregon Hearing Research Center at OHSU.

The discovery involved the use of advanced imaging technologies on guinea pigs, whose hearing in the low-frequency region is similar to that of humans.

The OHSU and Linköping scientists found that microscopic hair cells in the spiral-shaped inner ear, known as the cochlea, react simultaneously to low-frequency sound — a first-of-its-kind discovery that that could greatly improve the design and effectiveness of cochlear implants.

Until now, it was thought that each hair cell had its own “best frequency” to which it responded most, and cochlear implants are designed to mimic that process.

“This observation counters a century of consensus regarding frequency mapping in the inner ear,” Burwood said. “We spent a long while devising further controls and analyses to ensure what we had found stood up to scrutiny.”

Alfred Nuttall, Ph.D., in his lab at OHSU. (OHSU)
Alfred Nuttall, Ph.D. (OHSU)

In addition to Burwood, co-authors include Alfred Nuttall, Ph.D., director of the Oregon Hearing Research Center at OHSU; and Pierre Hakizimana and Anders Fridberger of Linköping University.

Research was supported by the National Institutes of Health, award R01-DC000141 and the Swedish Research Council, awards 2017-06092 and 2018-02692. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.

For more information, see the news release from Linköping University: https://liu.se/en/news-item/forskning-slar-hal-pa-gammal-bild-av-hur-var-horsel-fungerar

 

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