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 was suggesting that you paid attention to the part about going to the fair and (perhaps purposely) disregarded the bit about doing your chores.

But actually it takes an incredible act of cooperation between your ears and your brain to have selective hearing.

The Difficulty Of Trying to Hear in a Crowd

This scenario probably feels familiar: you’re feeling burnt out from a long day at work but your friends all really want to go out for dinner and drinks. And of course, they want to go to the loudest restaurant (because it’s popular and the deep-fried cauliflower is delicious). And you strain and struggle to follow the conversation for over an hour and a half.

But it’s very difficult and exhausting. This indicates that you could have hearing loss.

You think, maybe the restaurant was simply too loud. But… everyone else seemed to be having a fine go of it. You seemed like the only one experiencing trouble. Which gets you thinking: Why do ears that have hearing impairment have such a difficult time with the noise of a packed room? It seems as if hearing well in a crowd is the first thing to go, but what’s the reason? Scientists have begun to reveal the answer, and it all starts with selective hearing.

Selective Hearing – How Does it Work?

The term “selective hearing” is a process that doesn’t even happen in the ears and is scientifically called “hierarchical encoding”. The majority 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 basically work like a funnel: they collect all the impulses and then send the raw information to your brain. In the auditory cortex the real work is then accomplished. That’s the part of your gray matter that processes all those signals, translating impressions of moving air into recognizable sounds.

Because of considerable research with CT and MRI scans, scientists have recognized for years that the auditory cortex plays a significant role in hearing, but they were stumped with regards to what those processes actually look like. Thanks to some innovative 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 Hearing Hierarchy

And the insight they found out follows: the majority of the work done by the auditory cortex to isolate distinct voices is performed by two separate parts. And in loud conditions, they allow you to separate and intensify certain voices.

  • Superior temporal gyrus (STG): At some point your brain needs to make some value based decisions and this is done in the STG once it receives the voices which were previously separated by the HG. Which voices can be safely moved to the background and which ones you want to pay attention to is figured out by the STG..
  • Heschl’s gyrus (HG): The first sorting stage is managed by this part of the auditory cortex. Heschl’s gyrus or HG processes each individual voice and separates them into discrete identities.

When you begin to suffer from hearing problems, it’s harder for your brain to differentiate voices because your ears are missing certain 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 information. Consequently, it all blurs together (which makes discussions tough to follow).

A New Algorithm From New Science

It’s standard for hearing aids to have functions that make it less difficult to hear in a crowd. But hearing aid manufacturers can now incorporate more of those natural functions into their algorithms because they have a greater concept of what the process looks like. For instance, hearing aids that do more to distinguish voices can help out the Heschl’s gyrus a little bit, bringing about a better ability for you to understand what your coworkers are talking about in that noisy restaurant.

Technology will get better at mimicking what happens in nature as we discover more about how the brain works in conjunction with the ears. And better hearing outcomes will be the outcome. Then you can focus a little more on enjoying yourself and a little less on straining to hear.

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