Hearing Health Blog

Man can't hear in a crowded restaurant.

Selective hearing is a term that commonly gets tossed about as a pejorative, an insult. Maybe you heard your mother suggest that your father had “selective hearing” when she believed he might be ignoring her.

But it turns out that selective hearing is quite the talent, an amazing linguistic accomplishment executed by teamwork between your ears and brain.

The Difficulty Of Trying to Hear in a Crowd

This situation probably feels familiar: you’re feeling tired from a long workday but your friends all really want to go out for dinner and drinks. And of course, they want to go to the noisiest restaurant (because it’s trendy and the deep-fried cauliflower is the best in town). And you strain and struggle to follow the conversation for over an hour and a half.

But it’s tough, and it’s taxing. And it’s an indication of hearing loss.

You think, maybe the restaurant was just too loud. But no one else appeared to be struggling. It seemed like you were the only one experiencing trouble. So you start to ask yourself: Why do ears that have hearing impairment have such a difficult time with the noise of a packed room? It seems like hearing well in a crowded place 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.

How Does Selective Hearing Operate?

The scientific name for what we’re loosely calling selective hearing is “hierarchical encoding,” and it doesn’t happen in your ears at all. This process almost completely takes place in your brain. At least, that’s in accordance with a new study carried out by a team from Columbia University.

Scientists have recognized for quite some time that human ears essentially work as a funnel: they deliver all of the unprocessed data that they collect to your brain. In the auditory cortex the real work is then accomplished. That’s the part of your gray matter that handles all those signals, translating sensations of moving air into identifiable sounds.

Because of considerable research with MRI and CT scans, scientists have recognized for years that the auditory cortex plays a substantial role in hearing, but they were stumped regarding what those processes really look like. Thanks to some innovative research methods involving participants with epilepsy, scientists at Columbia were able to discover more about how the auditory cortex works when it comes to picking out voices in a crowd.

The Hierarchy of Hearing

And here’s what these intrepid scientists learned: there are two components of the auditory cortex that manage most of the work in allowing you to identify distinct voices. They’re what enables you to sort and amplify particular voices in noisy environments.

  • Heschl’s gyrus (HG): The first sorting phase is managed by this region of the auditory cortex. Heschl’s gyrus or HG processes each unique voice and separates them into discrete identities.
  • 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 differentiated by the HG. Which voices can be freely moved to the background and which ones you want to pay attention to is figured out by the STG..

When you have hearing impairment, your ears are lacking certain wavelengths so it’s harder for your brain to differentiate voices (low or high, based upon your hearing loss). Your brain isn’t provided with enough data to assign individual identities to each voice. It all blurs together as a consequence (which makes interactions hard to follow).

New Science = New Algorithm

It’s common for hearing aids to come with features that make it easier to hear in a crowd. But hearing aid makers can now include more of those natural functions into their algorithms because they have a better concept of what the process looks like. For instance, you will have a better ability to hear and understand what your coworkers are talking about with hearing aids that assist the Heshl’s gyrus and do a little more to identify voices.

The more we understand about how the brain works, especially in combination with the ears, the better new technology will be capable of mimicking what happens in nature. And that can lead to better hearing outcomes. That way, you can concentrate a little less on struggling to hear and a little more on enjoying yourself.

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