Navigation Links
New findings contradict a prevailing belief about the inner ear

ANN ARBOR, Mich.--- A healthy ear emits soft sounds in response to the sounds that travel in. Detectable with sensitive microphones, these otoacoustic emissions help doctors test newborns hearing. A deaf ear doesnt produce these echoes.

New research involving the University of Michigan and Oregon Health and Science University shows that, contrary to the current scientific thought, the emissions dont leave the ear the same way they entered. The findings give new insight into a phenomenon that researchers study to better understand hearing loss, and they reinforce a previous controversial study that came to a similar conclusion.

A paper on the research is published in the current issue of Proceedings of the National Academy of Sciences.

The former wisdom on how otoacoustic emissions left the ear was that there was a backward-traveling wave going along the structure of the cochlea in the same way as the forward-traveling sound wave, said Karl Grosh, a professor in the U-M departments of Mechanical Engineering and Biomedical Engineering and an author of the paper. These measurements show that is not the case.

Grosh said the next step is to develop tools to find out where hearing damage is occurring. If we want to try to infer from the emission whats wrong with the ear, we have to understand how the emission is produced, Grosh said.

The experiment, performed at the Oregon Health and Science University in associate professor Tianying Rens lab, showed that the sound waves coming out travel through the fluid of the inner ear, rather than rippling along the basilar membrane of the cochlea.

The cochlea, located deep in the ear, is shaped like a snail. The basilar membrane essentially cuts the inner channel of the cochlea diametrically in half into two chambers. Both chambers are filled with liquid.

Sound waves going into the ear undulate along the basilar membrane through the cochlea and eventually excite the organ of Corti, which senses and sends the sound signals to the brain through the auditory nerve.

Sounds coming out of the ear, according to results from this experiment, likely travel through the fluid on either side of the basilar membrane.

For this experiment, the researchers used laser interferometers, which detect waves, to measure vibrations of the basilar membrane in response to sound at two locations in the cochlea of gerbils. They detected evidence of sound waves traveling forward on the membrane, but they found no evidence of backward-traveling waves.

Our new method can detect vibrations of less than a picometer, 1,000 times smaller than the diameter of an atom. The new data demonstrate that there is no detectable backward-traveling wave at physiological sound levels across a wide frequency range, said Ren, principal investigator of this project. This knowledge will change scientists fundamental thinking on how waves propagate inside the cochlea, or how the cochlea processes sounds.


Contact: Nicole Casal Moore
University of Michigan

Related medicine news :

1. NeoStrata Clinical Findings Reveal Benefits of Combining Glycolic Acid Peels and Targeted Home Care With Microdermabrasion for Optimized Treatment of Photodamaged Skin
2. Distributes Key Findings on Global Specialty Medical Beds and Therapeutic Surfaces Market
3. New findings show Enbrel significantly reduced levels of C-reactive protein
4. New nanotube findings by Stanford researchers give boost to potential biomedical applications
5. NASA Releases Findings of Astronaut Survey
6. Findings point to molecular Achilles heel for half of breast cancer tumors
7. Researchers challenge previous findings regarding widely used asthma treatment
8. Statement From the Consumer Healthcare Products Association on the SAMHSA Findings on Cough Medicine Abuse
9. Chemoprevention, naturally: Findings on plant-derived cancer medicines
10. 2007 Life Sciences Compensation Findings Disclosed
11. Video: BSP Pharma Inc. Announces Groundbreaking Findings from The Australian Centre for Complementary Medicine Education and Research Joint Health Clinical Study
Post Your Comments:
(Date:6/26/2016)... , ... June 26, 2016 , ... ... once they have been diagnosed with endometriosis. These women need a treatment plan ... require a comprehensive approach that can help for preservation of fertility and ultimately ...
(Date:6/25/2016)... ... June 25, 2016 , ... First Choice Emergency Room , the ... Ogunleye, as the Medical Director of its new Mesquite-Samuell Farm facility. , “We ... new Mesquite location,” said Dr. James M. Muzzarelli, Executive Medical Director of First Choice ...
(Date:6/24/2016)... ... June 24, 2016 , ... A recent article published June ... with. The article goes on to state that individuals are now more comfortable seeking ... common operations such as calf and cheek reduction. The Los Angeles area medical group, ...
(Date:6/24/2016)... MIAMI, Fla. (PRWEB) , ... June 24, 2016 , ... ... Florida Trend magazine’s 2016 Legal Elite. The attorneys chosen by their peers for this ... of Florida. , Seven Greenberg Traurig Shareholders received special honors as members of this ...
(Date:6/24/2016)... ... 2016 , ... EB Medicine presented its first-ever “Issue of ... in Ponte Vedra Beach, FL. The awards honor the outstanding work of leading ... and Pediatric Emergency Medicine Practice. , “With this award, we recognize the efforts ...
Breaking Medicine News(10 mins):
(Date:6/23/2016)... MEDIA, Pa. , June 23, 2016 ... treatments in an outpatient dialysis facility.  Treatments are usually ... to 6 hours per visit, including travel time, equipment ... on a patient, but especially grueling for patients who ... residents of a skilled nursing and rehabilitation centers for ...
(Date:6/23/2016)... FRANKLIN, Tenn. , June 23, 2016 ... for automating, integrating and transforming the patient ... launch of several innovative new products and ... depth of its revenue cycle offerings. These ... establish more efficient workflows, remain compliant in ...
(Date:6/23/2016)... , June 23, 2016  The National Pharmaceutical ... joined the health policy research organization as its ... , MD, senior vice president and chief scientific ... representative on the NPC Board of Directors. ... that Mallinckrodt has joined us in support of ...
Breaking Medicine Technology: