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 modification of the design of future hearing aids.
Results from an MIT study debunked the notion that neural processing is what allows us to single out voices. Tuning into individual sound levels might actually be handled by a biochemical filter according to this study.
How Background Noise Impacts Our Ability to Hear
While millions of people fight hearing loss, only a fraction of them attempt to combat that hearing loss using hearing aids.
Although a hearing aid can provide a significant boost to one’s ability to hear, environments with lots of background noise have traditionally been an issue for individuals who wear a hearing improvement device. For example, the constant buzz associated with settings like parties and restaurants can wreak havoc on a person’s ability to discriminate a voice.
If you’re someone who is experiencing hearing loss, you very likely understand how frustrating and upsetting it can be to have a personal conversation with someone in a crowded room.
Scientists have been closely investigating hearing loss for decades. The way that sound waves move through the ear and how those waves are distinguished, due to this body of research, was thought to be well understood.
The Tectorial Membrane is Discovered
However, it was in 2007 that scientists identified the tectorial membrane within the inner ear’s cochlea. You won’t find this microscopic membrane made of a gel-like substance in any other parts of the body. What really intrigued scientists was how the membrane provides mechanical filtering that can decipher and delineate between sounds.
When vibration enters the ear, the tiny tectorial membrane manages how water moves in reaction using small pores as it rests on little hairs in the cochlea. Researchers observed that different frequencies of sound reacted differently to the amplification produced by the membrane.
The tones at the highest and lowest range appeared to be less impacted by the amplification, but the study found strong amplification among the middle tones.
Some scientists believe that more effective hearing aids that can better identify individual voices will be the result of this groundbreaking MIT study.
Hearing Aid Design of The Future
For years, the basic design concepts of hearing aids have remained relatively unchanged. A microphone to detect sound and a loudspeaker to amplify it are the basic components of hearing aids which, besides a few technology tweaks, have remained unchanged. This is, unfortunately, where the drawback of this design becomes apparent.
All frequencies are increased with an amplification device and that includes background noise. Another MIT scientist has long thought tectorial membrane exploration could result in new hearing aid designs that offer better speech recognition for wearers.
In theory, these new-and-improved hearing aids could functionally tune in to a distinct frequency range, which would enable the user to hear isolated sounds like a single voice. Only the desired frequencies would be amplified 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