How Do We Hear Voices in a Crowd?

How Do We Hear Voices in a Crowd?

By: | Tags: | Comments: 0 | February 14th, 2019

Duane L. Smelser

Thanks to the advances of hearing technology and research, many features of hearing are more clearly understood. We know more now than ever about the way that sound travels through space, reflection, and pushing tiny particles of air into pressurized zones. When it comes to the body, we know quite a lot, as well. Sound waves meet the exterior of the ear and travel in cascading waves through the tiny features of the middle and inner ear. Once sound reaches the auditory nerve, the process becomes a bit more mysterious. Sound is converted into electrical impulses that are sent to the brain for understanding, but the differences between those electrical impulses are indecipherable in many ways.

How does the brain differentiate the nuanced features of sound into language and identity? One of the great mysteries of the hearing process is how brain can differentiate one voice from another. Although we are beginning to understand how speech is becomes sounds, words, and other units of meaning, it has remained unclear how the mind can tell one voice from another. Particularly in a crowded room, how are we able to isolate one voice from another and make sense of what one speaker is saying? A loud restaurant or party is one of the most difficult hearing environments, and yet most of us are able to distinguish the voice of the speaker from the others in the room.


Basilar Membrane

We have known for at least 50 years that the basilar membrane plays a crucial part in the process of hearing. In order to create those electrical impulses that move to the brain through the auditory nerve, a channel must be able to differentiate such varied features as pitch, volume, and timbre. The cochlea are spiral-shaped, fluid-filled membranes that are lined with tiny hairs. Those tiny hairs are sensitive to subtle differences in sound, and the basilar membrane lining the cochlea is responsible for differentiating sounds from one another. Sounds of different frequencies actually break like waves over the ridges of the spiraling cochlea and the basilar membrane


Tectorial Membrane

The key to differentiating voices in a crowd comes from a much newer discovery in the hearing process. Researchers at MIT discovered in 2007 that the tectorial membrane is a gel-like substance found nowhere else in the body. It also lines the cochlea and is filled with tiny pores. Those pores allow through finely differentiated sounds, including frequency differences and volumes. However, the size of the pores is quite important to understanding differences.

When the pores are of the right size, they help us differentiate voices in a crowd. The trouble comes when these pores are either not sensitive enough to differences or, paradoxically, when they are too sensitive to differences in sound. Although tiny pores are highly sensitive to sound differences, they do not react quickly enough sound, making the process of hearing too slow to be effective.


Applying the Knowledge

For some hearing aid wearers, there is a complaint that hearing aids are not able to adequately isolate a single speaker in a room, but by discovering the role of the tectorial membrane, hearing aids may be able to simulate the mechanism of the pores. Now that we know more about the process of sound differentiation, some wonder if that knowledge can be applied to hearing assistance, as well. If researchers and technology developers were able to apply that knowledge to the design of hearing aids, one of their major weaknesses might be overcome.


Visit Us at Hearing Health in Portland

If you have a problem identifying the voice of a speaker from the many voices in a crowded room, it may be an early sign of hearing loss. Speech recognition is often challenging for people with untreated hearing loss. Don’t miss your chance to catch hearing loss before it gets any worse.

Treating hearing loss begins with a hearing test. Here at Hearing Health, we provide comprehensive hearing tests and hearing health services. If a hearing loss is detected, we will work with you to find the best solution to meet your hearing needs. Contact us today to schedule an appointment!

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