Researchers at the famed Massachusetts Institute of Technology (MIT) might have cracked the code on one of hearing’s most bewildering mysteries, and the revelation could lead to the modification of the design of future hearing aids.
The long standing idea that voices are singled out by neural processing has been debunked by an MIT study. According to the study, it may actually be a biochemical filter that enables us to tune in to specific levels of sound.
How Background Noise Impacts Our Ability to Hear
Only a small fraction of the millions of people who suffer from hearing loss actually use hearing aids to deal with it.
Though a hearing aid can provide a tremendous boost to one’s ability to hear, environments with lots of background noise have traditionally been a problem for individuals who use a hearing improvement device. A person’s ability to single out voices, for instance, can be seriously reduced in settings like a party or restaurant where there is a steady din of background noise.
If you’re a person who is experiencing hearing loss, you very likely recognize how annoying and stressful it can be to have a personal conversation with someone in a crowded room.
For decades scientists have been studying hearing loss. The way that sound waves move through the ear and how those waves are differentiated, 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 inside of the inner ear’s cochlea. You won’t find this microscopic membrane composed of a gel-like material in any other parts of the body. The deciphering and delineation of sound is achieved by a mechanical filtering carried out by this membrane and that may be the most intriguing thing.
Minute in size, the tectorial membrane rests on little hairs inside the cochlea, with small pores that control how water moves back and forth in response to vibrations. It was observed that the amplification created 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 revealed strong amplification among the middle frequencies.
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 allow for better single-voice identification.
Hearing Aid Design of The Future
The basic principles of hearing aid design haven’t changed much over the years. Tweaks and fine-tuning have helped with some enhancements, but the majority of hearing aids are basically made up of microphones that pick up sounds and a loudspeaker that amplifies them. This is, regrettably, where the drawback of this design becomes apparent.
Amplifiers, normally, are unable to differentiate between different frequencies of sounds, which means the ear gets boosted levels of all sounds, including background noise. Another MIT scientist has long thought tectorial membrane research could lead to new hearing aid designs that provide better speech recognition for wearers.
In theory, these new-and-improved hearing aids could functionally tune in to a specific frequency range, which would enable the user to hear isolated sounds such as a single voice. With this concept, the volume of those sounds would be the only sounds increased 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