About Careers Internship MedBlog Contact us
Medindia LOGIN REGISTER
Advertisement

Sound Localization in An Innate Function of Ears, But Researchers Are Still Doubtful Of Its Origin

by Rukmani Krishna on December 6, 2013 at 11:05 PM
 Sound Localization in An Innate Function of Ears, But Researchers Are Still Doubtful Of Its Origin

The ability to localize the source of sound is important for navigating the world. It is also helpful for listening in noisy environments like restaurants, an action that is particularly difficult for elderly or hearing impaired people. Having two ears allows animals to localize the source of a sound. For example, barn owls can snatch their prey in complete darkness by relying on sound alone. It has been known for a long time that this ability depends on tiny differences in the sounds that arrive at each ear, including differences in the time of arrival: in humans, for example, sound will arrive at the ear closer to the source up to half a millisecond earlier than it arrives at the other ear. These differences are called interaural time differences. However, the way that the brain processes this information to figure out where the sound came from has been the source of much debate.

Advertisement

A recent paper by Mass. Eye and Ear/Harvard Medical School researchers in collaboration with researchers at the Ecole Normale Superieure, France, challenge the two dominant theories of how people localize sounds, explain why neuronal responses to sounds are so diverse and show how sound can be localized, even with the absence of one half of the brain. Their research is described on line in the journal eLife.

"Progress has been made in laboratory settings to understand how sound localization works, but in the real world people hear a wide range of sounds with background noise and reflections," said Dan F. M. Goodman, lead author and post-doctoral fellow in the Eaton-Peabody Laboratories at Mass. Eye and Ear, Harvard Medical School. "Theories based on more realistic environments are important. The theme of the paper is that previous theories about this have been too idealized, and if you use more realistic data, you come to an entirely different conclusion."
Advertisement

"Two theories have come to dominate our understanding of how the brain localizes sounds: the peak coding theory (which says that only the most strongly responding brain cells are needed), and the hemispheric coding theory (which says that only the average response of the cells in the two hemispheres of the brain are needed)," Goodman said. "What we've shown in this study is that neither of these theories can be right, and that the evidence they presented only works because their experiments used unnatural/idealized sounds. If you use more realistic, natural sounds, then they both do very badly at explaining the data."

Researchers showed that to do well with realistic sounds, one needs to use the whole pattern of neural responses, not just the most strongly responding or average response. They showed two other key things: first, it has long been known that the responses of different auditory neurons are very diverse, but this diversity was not used in the hemispheric coding theory.

"We showed that the diversity is essential to the brain's ability to localize sounds; if you make all the responses similar then there isn't enough information, something that was not appreciated before because if one has unnatural/idealized sounds you don't see the difference" Goodman said.

Second, previous theories are inconsistent with the well-known fact that people are still able to localize sounds if they lose one half of our brain, but only sounds on the other side (i.e. if one loses the left half of the brain, he or she can still localize sounds coming from the right), he added.

"We can explain why this is the case with our new theory," Goodman said.

Source: Eurekalert
Font : A-A+

Advertisement

Advertisement
Advertisement

Latest Research News

Insight into Cellular Stress: Mechanisms Behind mRNA Sequestration Revealed
The discovery deepens our understanding of m6A biology and stress granule formation, with implications for neurodegenerative diseases.
Disrupted Circadian Rhythm Elevates the Risk of Parkinson's Disease
Trouble with sleep and the body's clock may increase your risk for Parkinson's, as per a new study.
A Wake-Up Call for Women  Hot Flashes Could Point to Alzheimer's Risk
New study uncovers a link between nocturnal hot flashes and Alzheimer's risk in menopausal women, suggesting a potential biomarker.
Breakthrough Brain-Centered Approach Reduces Chronic Back Pain
Our discovery revealed that a minority of individuals attributed their chronic pain to their brain's involvement.
New Statement to Protect Athletes' Health Published
Relative Energy Deficiency in Sport syndrome is overlooked by athletes and can be worsened by 'sports culture' due to its perceived short-term performance benefits.
View All
This site uses cookies to deliver our services.By using our site, you acknowledge that you have read and understand our Cookie Policy, Privacy Policy, and our Terms of Use  Ok, Got it. Close
MediBotMediBot
Greetings! How can I assist you?MediBot
×

Sound Localization in An Innate Function of Ears, But Researchers Are Still Doubtful Of Its Origin Personalised Printable Document (PDF)

Please complete this form and we'll send you a personalised information that is requested

You may use this for your own reference or forward it to your friends.

Please use the information prudently. If you are not a medical doctor please remember to consult your healthcare provider as this information is not a substitute for professional advice.

Name *

Email Address *

Country *

Areas of Interests