Researchers at the famous Massachusetts Institute of Technology (MIT) may have cracked the code on one of hearing’s most bewildering mysteries, and the insight could lead to the overhauling of the design of future hearing aids.
Findings from an MIT study debunked the belief that neural processing is what lets us single out voices. According to the study, it might actually be a biochemical filter that allows us to tune in to individual levels of sound.
How Background Noise Impacts Our Ability to Hear
Only a small portion of the millions of people who cope with hearing loss actually use hearing aids to manage it.
Although a hearing aid can provide a significant boost to one’s ability to hear, settings with lots of background noise have traditionally been an issue for people who use a hearing improvement device. A person’s ability to discriminate voices, for example, can be drastically reduced in settings like a party or restaurant where there is a constant din of background noise.
Having a conversation with someone in a crowded room can be stressful and annoying and people who deal with hearing loss know this all too well.
For decades scientists have been studying hearing loss. The way that sound waves travel through the ear and how those waves are differentiated, due to this body of research, was thought to be well understood.
The Tectorial Membrane is Discovered
But the tectorial membrane wasn’t discovered by scientists until 2007. The ear is the only place on the body you will find this gel-like membrane. The deciphering and delineation of sound is achieved by a mechanical filtering performed by this membrane and that might be the most fascinating thing.
Minute in size, the tectorial membrane rests on little hairs within the cochlea, with small pores that control how water moves back and forth in reaction to vibrations. It was observed that the amplification produced by the membrane caused a different reaction to different frequencies of sound.
The frequencies at the highest and lowest end of the spectrum seemed to be less impacted by the amplification, but the study found strong amplification in the middle frequencies.
Some scientists think that more effective hearing aids that can better distinguish individual voices will be the outcome of this groundbreaking MIT study.
The Future of Hearing Aid Design
For years, the general design principles of hearing aids have remained rather unchanged. A microphone to pick up sound and a loudspeaker to amplify it are the basic elements of hearing aids which, besides a few technology tweaks, have remained the same. This is, unfortunately, where the shortcoming of this design becomes apparent.
All frequencies are increased with an amplification device and that includes background noise. Another MIT researcher has long thought tectorial membrane research could lead to new hearing aid designs that provide better speech recognition for users.
The user of these new hearing aids could, theoretically, tune in to a specific voice as the hearing aid would be able to tune specific frequencies. Only the chosen frequencies would be increased with these hearing aids and everything else would be left alone.
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References
https://www.machinedesign.com/motion-control/researchers-discover-secret-how-we-can-pick-out-voice-crowd
http://www.xinhuanet.com/english/2019-01/16/c_137749535.htm
https://medicalxpress.com/news/2010-11-tuning-mechanism.html
