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Man can't hear in a crowded restaurant.

Selective hearing is a phrase that commonly gets tossed about as a pejorative, an insult. Perhaps you heard your mother accuse your father of having “selective hearing” when she believed he was ignoring her.

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

The Stress Of Trying to Hear in a Crowd

Maybe you’ve encountered this situation before: you’re feeling burnt out from a long day at work but your friends all really would like to go out for dinner and drinks. And naturally, they want to go to the loudest restaurant (because it’s popular and the food is the best in town). And you spend an hour and a half straining your ears, working hard to follow the conversation.

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

Maybe, you rationalize, the restaurant was just too loud. But… everyone else appeared to be having a great time. It seemed like you were the only one experiencing trouble. 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? It seems like hearing well in a crowded place is the first thing to go, but why? The solution, as reported by scientists, is selective hearing.

How Does Selective Hearing Work?

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

Scientists have recognized for quite some time that human ears essentially work like a funnel: they collect all the signals and then send the raw information to your brain. That’s where the heavy lifting occurs, particularly the auditory cortex. Vibrations caused by moving air are translated by this portion of the brain into perceptible sound information.

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

The Hierarchy of Hearing

And here’s what these intrepid scientists found out: most of the work accomplished by the auditory cortex to pick out particular voices is done by two separate regions. And in loud environments, they enable you to separate and boost certain voices.

  • Heschl’s gyrus (HG): The first sorting phase is handled by this region of the auditory cortex. Heschl’s gyrus or HG processes each individual voice and separates them into discrete identities.
  • Superior temporal gyrus (STG): At some point your brain will need to make some value based choices and this occurs in the STG once it receives the voices which were previously differentiated by the HG. The superior temporal gyrus determines which voices you want to give attention to and which can be securely moved to the background.

When you begin to suffer from hearing problems, it’s more difficult for your brain to differentiate voices because your ears are lacking specific wavelengths of sound (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 data. It all blurs together as a consequence (which makes interactions tough to follow).

New Science = New Algorithm

It’s standard for hearing aids to come with features that make it less difficult to hear in a crowd. But now that we know what the basic process looks like, hearing aid makers can incorporate more of those natural functions into their instrument algorithms. For instance, you will have a better capacity to hear and understand what your coworkers are talking about with hearing aids that help the Heshl’s gyrus and do a little more to distinguish voices.

Technology will get better at mimicking what takes place in nature as we discover more about how the brain functions in combination with the ears. And better hearing success will be the result. That way, you can concentrate a little less on straining to hear and a little more on enjoying yourself.