Navigation Links
New findings contradict a prevailing belief about the inner ear
Date:2/12/2008

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
ncmoore@umich.edu
734-647-1838
University of Michigan
Source:Eurekalert

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. MarketResearch.com 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 www.compstudy.com
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:
*Name:
*Comment:
*Email:
(Date:10/13/2017)... ... October 13, 2017 , ... Global Healthcare Management’s 4th Annual Kids Fun Run ... This free event, sponsored by Global Healthcare Management’s CEO, Jon Letko, is aimed ... geared towards children of all ages; it is a non-competitive, non-timed event, which is ...
(Date:10/13/2017)... , ... October 13, 2017 , ... ... be giving viewers the lowdown on sciatica in a new episode of "Success ... focuses on current events and innovation and investigates each subject in-depth with passion ...
(Date:10/13/2017)... ... October 13, 2017 , ... “The Journey: From the Mountains to the ... save lost souls in the Philippines. “The Journey: From the Mountains to the Mission ... of the Bible. She has taught all ages and currently teaches a class of ...
(Date:10/12/2017)... ... October 12, 2017 , ... First ... compliance program management, will showcase a range of technology and learning solutions at ... (NCAL) Convention and Expo to be held October 14–18, 2017 at the Mandalay ...
(Date:10/12/2017)... ... October 12, 2017 , ... Planet Fitness, one of the largest ... its plans to open a flagship location in Covington, LA at 401 N. U.S. ... Go store next to Office Depot in the Holiday Square shopping center. Its location ...
Breaking Medicine News(10 mins):
(Date:10/4/2017)...  South Korean-based healthcare product Development Company I.M. Lab ... Kickstarter. The device will educate the user about ,proper, ... efficiency compared to the dated and pricey CPR training ... of the compression for a more informed CPR training. ... raise $5,000. cprCUBE ...
(Date:10/2/2017)... Oct. 2, 2017  AllianceRx Walgreens Prime, the combined ... Walgreens and pharmacy benefit manager Prime Therapeutics LLC (Prime), ... which included the unveiling of new signage at its ... well as at a few other company-owned facilities across ... to patients, some of whom will begin to see ...
(Date:9/27/2017)... MIAMI , Sept. 27, 2017  Commended for their ... recent notable awards. Ranked as number one in the South ... ninth time in Inc. 5000 yearly list, the national specialty ... CEO, Armando Bardisa will soon be honored by ... Set to receive his award ...
Breaking Medicine Technology: