Researchers at the famed Massachusetts Institute of Technology (MIT) might have cracked the code on one of hearing’s most bewildering mysteries, and the insight could result in the overhauling of the design of future hearing aids.
The long standing notion that voices are singled out by neural processing has been debunked by an MIT study. Tuning into specific sound levels might actually be managed by a biochemical filter according to this study.
How Background Noise Impacts Our Ability to Hear
While millions of individuals battle hearing loss, only a fraction of them try to deal with that hearing loss with the use of hearing aids.
Though a hearing aid can give a significant boost to one’s ability to hear, those who wear a hearing-improvement device have typically still had trouble in settings with copious amounts of background noise. A person’s ability to single out 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 upsetting and annoying and people who suffer from hearing loss know this all too well.
Scientists have been meticulously studying hearing loss for decades. Due to those efforts, the way that sound waves travel throughout the inner ear, and how the ear distinguishes different frequencies of sounds, was thought to be well-understood.
The Tectorial Membrane is Identified
However, it was in 2007 that scientists identified the tectorial membrane inside of the inner ear’s cochlea. You won’t see this microscopic membrane made of a gel-like material in any other parts of the body. What really fascinated scientists was how the membrane provides mechanical filtering that can decipher and delineate between sounds.
When vibration comes into the ear, the minute tectorial membrane manages how water moves in reaction using small pores as it sits on little hairs in the cochlea. It was noted that the amplification produced by the membrane caused a different reaction to different frequencies of sound.
The frequencies at the highest and lowest range seemed to be less affected by the amplification, but the study found strong amplification in the middle tones.
It’s that development that leads some scientists to believe MIT’s groundbreaking discovery could be the conduit to more effective hearing aids that ultimately enable better single-voice identification.
Hearing Aid Design of The Future
The fundamental principles of hearing aid design haven’t changed very much over the years. A microphone to pick up sound and a loudspeaker to amplify it are the basic components of hearing aids which, besides a few technology tweaks, have remained unchanged. Unfortunately, that’s where one of the design’s shortcomings becomes clear.
Amplifiers, typically, are unable to differentiate between different levels of sounds, which means the ear receives boosted levels of all sounds, including background noise. Another MIT scientist has long believed tectorial membrane exploration could result in new hearing aid designs that offer better speech recognition for wearers.
Theoretically, these new-and-improved hearing aids could functionally tune in to a distinct frequency range, which would enable the user to hear isolated sounds such as 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