Man can't hear in a crowded restaurant.

Selective hearing is a term that usually gets tossed about as a pejorative, an insult. When your mother used to accuse you of having “selective hearing,” she meant that you paid attention to the part about going to the fair and (maybe purposely) ignored the bit about doing your chores.

But in reality it takes an amazing act of teamwork between your brain and your ears to have selective hearing.

Hearing in a Crowd

This situation probably seems familiar: you’re feeling tired from a long day at work but your friends all really would like to go out for dinner and drinks. They choose the loudest restaurant (because they have amazing food and live entertainment). And you strain and struggle to understand the conversation for over an hour and a half.

But it’s challenging, and it’s taxing. And it’s a sign of hearing loss.

You think, perhaps the restaurant was simply too loud. But no one else seemed to be having difficulties. It seemed like you were the only one having difficulty. So you start to wonder: what is it about the crowded room, the cacophony of voices all trying to be heard, that causes hearing impaired ears to struggle? Just why is it that being able to hear in a crowd is so challenging? Scientists have begun to discover the solution, and it all starts with selective hearing.

How Does Selective Hearing Work?

The scientific term for what we’re broadly calling selective hearing is “hierarchical encoding,” and it doesn’t happen inside of your ears at all. This process nearly entirely happens in your brain. At least, that’s as reported by a new study done by a team at Columbia University.

Scientists have recognized for quite a while that human ears basically work as a funnel: they deliver all of the raw data that they collect to your brain. In the auditory cortex the real work is then done. Vibrations caused by moving air are translated by this portion of the brain into perceptible sound information.

Precisely what these processes look like was still unknown in spite of the existing understanding of the role played by the auditory cortex in the process of hearing. Thanks to some innovative research methods concerning participants with epilepsy, scientists at Columbia were able to find out more about how the auditory cortex functions in relation to discerning voices in a crowd.

The Hearing Hierarchy

And the information they discovered are as follows: most of the work accomplished by the auditory cortex to isolate particular voices is done by two different parts. And in noisy settings, they allow you to isolate and boost certain voices.

  • Superior temporal gyrus (STG): Eventually your brain will need to make some value based choices and this is done in the STG once it receives the voices that were previously separated by the HG. The superior temporal gyrus determines which voices you want to focus on and which can be confidently moved to the background.
  • Heschl’s gyrus (HG): The first sorting phase is handled by this region of the auditory cortex. Heschl’s gyrus or HG breaks down each individual voice and separates them into discrete identities.

When you have hearing loss, your ears are missing specific wavelengths so it’s more difficult for your brain to recognize voices (depending on your hearing loss it might be high or low frequencies). Your brain can’t assign separate identities to each voice because it doesn’t have enough information. It all blends together as a result (which makes conversations difficult to follow).

A New Algorithm From New Science

Hearing aids already have features that make it easier to hear in noisy circumstances. But hearing aid manufacturers can now incorporate more of those natural functions into their algorithms because they have a greater idea of what the process looks like. As an example, you will have a greater capacity to hear and understand what your coworkers are saying with hearing aids that help the Heshl’s gyrus and do a little more to identify voices.

The more we understand about how the brain works, specifically in connection with the ears, the better new technology will be able to mimic what takes place in nature. And that can result in improved hearing outcomes. That way, you can focus a little less on straining to hear and a little more on enjoying yourself.

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