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 in the journal Science Advances, may make it possible to design better cochlear implants for people with hearing impairments.
“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.
Research Counters a ‘Century of Consensus’ on Frequency Mapping in Inner Ear
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. We spent a long while devising further controls and analyses to ensure what we had found stood up to scrutiny.”
–George Burwood, PhD
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
Source: Erik Robinson, OHSU
It appears that these scientists do not have the conceptual capacity to relate the low frequency environment in our planet to speech. Speech just happens to be a microscopic segment of sounds that si specifically designed for brain responses in the human species. Low frequency sounds are for environmental balance.
The main synaptic mode from the 8th nerve branches into the CA complex and then it’s tentacles reach into the amygdala and then back into the pyramidal complex of neurons that are set up for advanced signal processing. This set of actions do not occur in the cochlea. But within the spiral ganglion.