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Man can't hear in a crowded restaurant.

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

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

Hearing in a Crowd

Perhaps you’ve dealt with this situation before: 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 popular and the deep-fried cauliflower is delicious). And you strain and struggle to understand the conversation for over an hour and a half.

But it’s very difficult and exhausting. And it’s a sign of hearing loss.

Perhaps, you rationalize, the restaurant was simply too loud. But… everyone else appeared to be having a fine go of it. The only person who appeared to be having difficulty was you. 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 started to reveal the answer, and it all begins 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 inside of your ears at all. This process almost entirely happens in your brain. At least, that’s as reported by a new study done by a team at Columbia University.

Ears work like a funnel which scientists have recognized for some time: they send all of the raw data that they collect to your brain. In the auditory cortex the real work is then accomplished. That’s the part of your brain that processes all those signals, translating impressions of moving air into perceptible sounds.

Because of extensive research with CT and MRI scans, scientists have recognized for years that the auditory cortex plays a considerable role in hearing, but they were clueless when it came to what those processes actually look like. Scientists were able, by utilizing novel research techniques on people with epilepsy, to get a better picture of how the auditory cortex picks out voices in a crowd.

The Hierarchy of Hearing

And the information they found are as follows: there are two parts of the auditory cortex that do most of the work in allowing you to key in on individual voices. And in loud environments, they enable you to separate and enhance specific voices.

  • Superior temporal gyrus (STG): The separated 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 freely moved to the background and which ones you want to focused on is determined by the STG..
  • Heschl’s gyrus (HG): The first sorting stage is managed by this region of the auditory cortex. Researchers discovered that the Heschl’s gyrus (we’re simply going to call it HG from now on) was processing each distinct voice, separating them into individual identities.

When you have hearing impairment, your ears are missing particular wavelengths so it’s more difficult for your brain to recognize voices (high or low, depending on your hearing loss). Your brain isn’t provided with enough data to assign separate identities to each voice. It all blurs together as a consequence (which makes conversations tough to follow).

A New Algorithm From New Science

Hearing aids already have functions that make it easier to hear in loud circumstances. But hearing aid manufacturers can now integrate more of those natural functions into their algorithms because they have a better concept of what the process looks like. As an example, you will have a better ability to hear and understand what your coworkers are saying with hearing aids that assist the Heshl’s gyrus and do a little more to separate voices.

Technology will get better at mimicking what takes place in nature as we uncover more about how the brain works in conjunction with the ears. And better hearing outcomes will be the outcome. That way, you can concentrate a little less on struggling to hear and a little more on enjoying yourself.

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