Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Nanopores control the inner ear's ability to select sounds: Inner-ear membrane uses tiny pores to mechanically separate sounds, researchers find

This optical microscope image depicts wave motion in a cross-section of the tectorial membrane, part of the inner ear. This membrane is a microscale gel, smaller in width than a single human hair, and it plays a key role in stimulating sensory receptors of the inner ear. Waves traveling on this membrane control our ability to separate sounds of varying pitch and intensity.  
Image courtesy of MIT's Micromechanics Group
This optical microscope image depicts wave motion in a cross-section of the tectorial membrane, part of the inner ear. This membrane is a microscale gel, smaller in width than a single human hair, and it plays a key role in stimulating sensory receptors of the inner ear. Waves traveling on this membrane control our ability to separate sounds of varying pitch and intensity.

Image courtesy of MIT's Micromechanics Group

Abstract:
Even in a crowded room full of background noise, the human ear is remarkably adept at tuning in to a single voice a feat that has proved remarkably difficult for computers to match. A new analysis of the underlying mechanisms, conducted by researchers at MIT, has provided insights that could ultimately lead to better machine hearing, and perhaps to better hearing aids as well.

Nanopores control the inner ear's ability to select sounds: Inner-ear membrane uses tiny pores to mechanically separate sounds, researchers find

Cambridge, MA | Posted on March 18th, 2014

Our ears' selectivity, it turns out, arises from evolution's precise tuning of a tiny membrane, inside the inner ear, called the tectorial membrane. The viscosity of this membrane its firmness, or lack thereof depends on the size and distribution of tiny pores, just a few tens of nanometers wide. This, in turn, provides mechanical filtering that helps to sort out specific sounds.

The new findings are reported in the Biophysical Journal by a team led by MIT graduate student Jonathan Sellon, and including research scientist Roozbeh Ghaffari, former graduate student Shirin Farrahi, and professor of electrical engineering Dennis Freeman. The team collaborated with biologist Guy Richardson of the University of Sussex.

Elusive understanding

In discriminating among competing sounds, the human ear is "extraordinary compared to conventional speech- and sound-recognition technologies," Freeman says. The exact reasons have remained elusive but the importance of the tectorial membrane, located inside the cochlea, or inner ear, has become clear in recent years, largely through the work of Freeman and his colleagues. Now it seems that a flawed assumption contributed to the longstanding difficulty in understanding the importance of this membrane.

Much of our ability to differentiate among sounds is frequency-based, Freeman says so researchers had "assumed that the better we could resolve frequency, the better we could hear." But this assumption turns out not always to be true.

In fact, Freeman and his co-authors previously found that tectorial membranes with a certain genetic defect are actually highly sensitive to variations in frequency and the result is worse hearing, not better.

The MIT team found "a fundamental tradeoff between how well you can resolve different frequencies and how long it takes to do it," Freeman explains. That makes the finer frequency discrimination too slow to be useful in real-world sound selectivity.

Too fast for neurons

Previous work by Freeman and colleagues has shown that the tectorial membrane plays a fundamental role in sound discrimination by carrying waves that stimulate a particular kind of sensory receptor. This process is essential in deciphering competing sounds, but it takes place too quickly for neural processes to keep pace. Nature, over the course of evolution, appears to have produced a very effective electromechanical system, Freeman says, that can keep up with the speed of these sound waves.

The new work explains how the membrane's structure determines how well it filters sound. The team studied two genetic variants that cause nanopores within the tectorial membrane to be smaller or larger than normal. The pore size affects the viscosity of the membrane and its sensitivity to different frequencies.

The tectorial membrane is spongelike, riddled with tiny pores. By studying how its viscosity varies with pore size, the team was able to determine that the typical pore size observed in mice about 40 nanometers across represents an optimal size for combining frequency discrimination with overall sensitivity. Pores that are larger or smaller impair hearing.

"It really changes the way we think about this structure," Ghaffari says. The new findings show that fluid viscosity and pores are actually essential to its performance. Changing the sizes of tectorial membrane nanopores, via biochemical manipulation or other means, can provide unique ways to alter hearing sensitivity and frequency discrimination.

###

The research was supported by the National Institutes of Health; the National Science Foundation; and the Wellcome Trust.

Written by David Chandler, MIT News Office

####

For more information, please click here

Contacts:
Abby Abazorius

617-253-2709

Copyright © Massachusetts Institute of Technology

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

Archive: Tuning in to a new hearing mechanism:

Archive: MIT finds new hearing mechanism:

Related News Press

News and information

Report highlights opportunities and risks associated with synthetic biology and bioengineering November 22nd, 2017

Quantum optics allows us to abandon expensive lasers in spectroscopy: Lomonosov Moscow State University scientists have invented a new method of spectroscopy November 21st, 2017

Nano-watch has steady hands November 21st, 2017

Nano Global, Arm Collaborate on Artificial Intelligence Chip to Drive Health Revolution by Capturing and Analyzing Molecular Data in Real Time November 21st, 2017

Govt.-Legislation/Regulation/Funding/Policy

EC Project Aims at Creating and Commercializing Cyber-Physical-System Solutions November 14th, 2017

Nanobiotix presented new clinical and pre-clinical data confirming NBTXR3s significant potential role in Immuno-Oncology at SITC Annual Meeting November 14th, 2017

Leti Joins DARPA-Funded Project to Develop Implantable Device for Restoring Vision November 9th, 2017

Nanoshells could deliver more chemo with fewer side effects: In vitro study verifies method for remotely triggering release of cancer drugs November 8th, 2017

Nanomedicine

Nanoparticles could allow for faster, better medicine: Exposure of nanoparticles in the body allows for more effective delivery November 20th, 2017

Nanobiotix presented new clinical and pre-clinical data confirming NBTXR3s significant potential role in Immuno-Oncology at SITC Annual Meeting November 14th, 2017

Arrowhead to Present at 29th Annual Piper Jaffray Healthcare Conference November 14th, 2017

A new way to mix oil and water: Condensation-based method developed at MIT could create stable nanoscale emulsions November 8th, 2017

Discoveries

Quantum optics allows us to abandon expensive lasers in spectroscopy: Lomonosov Moscow State University scientists have invented a new method of spectroscopy November 21st, 2017

Nano-watch has steady hands November 21st, 2017

Nanoparticles could allow for faster, better medicine: Exposure of nanoparticles in the body allows for more effective delivery November 20th, 2017

ICN2 researchers compute unprecedented values for spin lifetime anisotropy in graphene November 17th, 2017

Announcements

Report highlights opportunities and risks associated with synthetic biology and bioengineering November 22nd, 2017

Quantum optics allows us to abandon expensive lasers in spectroscopy: Lomonosov Moscow State University scientists have invented a new method of spectroscopy November 21st, 2017

Nano-watch has steady hands November 21st, 2017

Nano Global, Arm Collaborate on Artificial Intelligence Chip to Drive Health Revolution by Capturing and Analyzing Molecular Data in Real Time November 21st, 2017

Grants/Sponsored Research/Awards/Scholarships/Gifts/Contests/Honors/Records

Math gets real in strong, lightweight structures: Rice University researchers use 3-D printers to turn century-old theory into complex schwarzites November 16th, 2017

Oxford Instruments announces winner of the 2017 Sir Martin Wood Prize for Japan November 14th, 2017

A new way to mix oil and water: Condensation-based method developed at MIT could create stable nanoscale emulsions November 8th, 2017

Nanoshells could deliver more chemo with fewer side effects: In vitro study verifies method for remotely triggering release of cancer drugs November 8th, 2017

Research partnerships

Nano Global, Arm Collaborate on Artificial Intelligence Chip to Drive Health Revolution by Capturing and Analyzing Molecular Data in Real Time November 21st, 2017

EC Project Aims at Creating and Commercializing Cyber-Physical-System Solutions November 14th, 2017

Leti Joins DARPA-Funded Project to Develop Implantable Device for Restoring Vision November 9th, 2017

Nanoshells could deliver more chemo with fewer side effects: In vitro study verifies method for remotely triggering release of cancer drugs November 8th, 2017

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project