Researchers at the famed Massachusetts Institute of Technology (MIT) may have cracked the code on one of hearing’s most mystifying mysteries, and the insight could lead to the modification of the design of future hearing aids.
Findings from an MIT study debunked the belief that neural processing is what allows us to single out voices. Tuning into specific levels of sound may actually be managed by a biochemical filter according to this study.
How Background Noise Effects Our Ability to Hear
While millions of individuals fight hearing loss, only a fraction of them attempt to overcome that hearing loss using hearing aids.
Even though a hearing aid can give a significant boost to one’s ability to hear, those who use a hearing-improvement device have commonly still struggled in environments with copious amounts of background noise. A person’s ability to single out voices, for example, can be severely limited in settings like a party or restaurant where there is a steady din of background noise.
Having a discussion with somebody in a crowded room can be upsetting and frustrating and people who cope 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 distinguished, due to this body of research, was believed 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 see 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.
Minute in size, the tectorial membrane sits on little hairs inside 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 middle tones were shown to have strong amplification and the frequencies at the lower and higher ends of the spectrum were less affected.
Some scientists believe 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 basic design principles of hearing aids have remained rather unchanged. Adjustments and fine-tuning have helped with some enhancements, but the majority of hearing aids are basically comprised of microphones which pick up sounds and a loudspeaker that amplifies them. This is, regrettably, where the drawback of this design becomes apparent.
All frequencies are increased with an amplification device and that includes background noise. Tectorial membrane research could, according to another MIT scientist, lead to new, innovative hearing aid designs which would offer better speech recognition.
Theoretically, these new-and-improved hearing aids could functionally tune to a specific frequency range, which would allow the user to hear isolated sounds like a single voice. With this concept, the volume of those sounds would be the only sounds boosted to aid in reception.
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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