Hearing Services of Nashville

Man can't hear in a crowded restaurant.

Selective hearing is a phrase that normally is used as a pejorative, an insult. When your mother used to accuse you of having “selective hearing,” she meant that you listened to the part about chocolate cake for dessert and (maybe deliberately) disregarded the part about doing your chores.

But actually selective hearing is quite the ability, an amazing linguistic task carried out by cooperation between your ears and brain.

Hearing in a Crowd

This situation potentially seems familiar: you’ve had a long day at work, but your buddies all insist on meeting up for dinner. And naturally, they want to go to the noisiest restaurant (because they have incredible food and live entertainment). And you strain and struggle to understand the conversation for the entire evening.

But it’s very difficult and exhausting. And it’s an indication of hearing loss.

Perhaps, you rationalize, the restaurant was simply too noisy. But… everyone else appeared to be having a great time. It seemed like you were the only one experiencing difficulty. So you start to ask yourself: Why do ears that have hearing impairment have such a difficult time with the noise of a crowded room? It seems like hearing well in a crowd is the first thing to go, but what’s the reason? Scientists have begun to uncover the solution, and it all starts with selective hearing.

Selective Hearing – How Does it Work?

The scientific term for what we’re loosely calling selective hearing is “hierarchical encoding,” and it doesn’t happen in your ears at all. Most of this process happens in the brain. At least, that’s in line with a new study carried out by a team from Columbia University.

Scientists have known for some time that human ears effectively work as a funnel: they collect all the impulses and then forward the raw data to your brain. That’s where the heavy lifting happens, particularly the auditory cortex. That’s the part of your brain that handles all those impulses, interpreting impressions of moving air into perceptible sounds.

Because of significant research with MRI and CT scans, scientists have understood for years that the auditory cortex plays a considerable role in hearing, but they were clueless regarding what those processes really look like. Thanks to some novel research techniques involving participants with epilepsy, scientists at Columbia were able to learn more about how the auditory cortex functions when it comes to discerning voices in a crowd.

The Hierarchy of Hearing

And the facts they found out are as follows: most of the work done by the auditory cortex to pick out distinct voices is accomplished by two separate parts. They’re what enables you to sort and intensify distinct voices in loud situations.

  • Superior temporal gyrus (STG): The differentiated voices move from the HG to the STG, and it’s at this point that your brain begins to make some value distinctions. Which voices can be safely moved to the background and which ones you want to focused on is figured out by the STG..
  • Heschl’s gyrus (HG): This is the part of the auditory cortex that takes care of the first stage of the sorting process. Heschl’s gyrus or HG breaks down each unique voice and separates them into distinguishable identities.

When you start to suffer from hearing problems, it’s more difficult for your brain to differentiate voices because your ears are missing specific wavelengths of sound (high or low, depending on your hearing loss). Your brain can’t assign individual identities to each voice because it doesn’t have enough data. As a result, it all blends together (which makes interactions difficult to follow).

A New Algorithm From New Science

It’s common for hearing aids to come with features that make it easier to hear in a crowded situation. But hearing aid makers 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 assist the Heshl’s gyrus and do a little more to identify voices.

The more we learn about how the brain works, especially in combination with the ears, the better new technology will be capable of mimicking what takes place in nature. And that can lead to better hearing success. Then you can concentrate a little more on enjoying yourself and a little less on straining to hear.

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