New findings on how the ear hears could lead to better hearing aids

Aug 20, 2013
A healthy ear is much better at detecting and transmitting sound than even the most advanced hearing aid. But now researchers reporting in the August 20 issue of the Biophysical Journal, a Cell Press publication, have uncovered new insights into how the ear -- in particular, the cochlea -- processes and amplifies sound. The findings could be used for the development of better devices to improve hearing. Credit: Biophysical Journal, Dong et al.

A healthy ear is much better at detecting and transmitting sound than even the most advanced hearing aid. But now researchers reporting in the August 20 issue of the Biophysical Journal, a Cell Press publication, have uncovered new insights into how the ear—in particular, the cochlea—processes and amplifies sound. The findings could be used for the development of better devices to improve hearing.

Sound-sensing cells within the cochlea—called hair cells due to the presence of cilia on their membrane surfaces—vibrate strongly at different sound frequencies depending on their location. To examine the cochlear electro-mechanics responsible for this process, Dr. Elizabeth Olson and Dr. Wei Dong, both of Columbia University, designed that could simultaneously measure small and cell-generated voltages at specific locations within the ears of live gerbils.

It was previously shown that the pivoting of cilia on a hair cell mechanically opens ion channels in the cell membrane, allowing the current to flow and generate voltage. This sends a signal to a nerve cell, which relays the specific sound frequency signal to the brain. In addition, energy released by hair cell voltage feeds back to amplify the motion specific to that location's frequency, thus driving additional movement of the local .

Dr. Dong and Dr. Olson discovered that a shift in the timing of this feedback voltage activates amplification at the right frequencies. With the shift, hair cell forces pump energy into cochlear motion, much like a child increases a swing's motion by pumping his legs at the right time. In addition to detecting the amplification trigger, the researchers' sensors verified the amplification that results.

Today's —which send amplified signals to the whole cochlea—cannot duplicate this location- and frequency-specific amplification, and understanding how the cochlea accomplishes this may lead to major advances.

"Several groups around the world are devising electromechanical cochlear prostheses, or next-generation cochlear implants. Understanding the micro-mechanical machine of the natural cochlea will inspire and guide these developments," says Dr. Olson.

Explore further: First in-situ images of void collapse in explosives

More information: Biophysical Journal, Dong et al.: "Detection of Cochlear Amplification and Its Activation." dx.doi.org/10.1016/j.bpj.2013.06.049

Related Stories

Recommended for you

First in-situ images of void collapse in explosives

Jul 25, 2014

While creating the first-ever images of explosives using an x-ray free electron laser in California, Los Alamos researchers and collaborators demonstrated a crucial diagnostic for studying how voids affect ...

New approach to form non-equilibrium structures

Jul 24, 2014

Although most natural and synthetic processes prefer to settle into equilibrium—a state of unchanging balance without potential or energy—it is within the realm of non-equilibrium conditions where new possibilities lie. ...

Nike krypton laser achieves spot in Guinness World Records

Jul 24, 2014

A set of experiments conducted on the Nike krypton fluoride (KrF) laser at the U.S. Naval Research Laboratory (NRL) nearly five years ago has, at long last, earned the coveted Guinness World Records title for achieving "Highest ...

User comments : 0