Man can't hear in a crowded restaurant.

Selective hearing is a term that commonly 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 intentionally) disregarded the part about cleaning your room.

But actually selective hearing is quite the ability, an impressive linguistic feat conducted by teamwork between your brain and ears.

Hearing in a Crowd

Maybe 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 naturally, they want to go to the noisiest restaurant (because it’s trendy and the deep-fried cauliflower is delicious). And you spend the entire evening straining your ears, working hard to follow the conversation.

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

You think, maybe the restaurant was just too loud. But… everyone else appeared to be having a fine go of it. It seemed like you were the only one experiencing trouble. Which makes you think: 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 crowded place is the first thing to go, but what’s the reason? Scientists have begun to reveal the answer, and it all begins 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 exclusively occurs in your brain. At least, that’s in line with a new study done by a team at Columbia University.

Ears work just like a funnel which scientists have understood for some time: they gather all the impulses and then deliver the raw information to your brain. That’s where the heavy lifting takes place, particularly the auditory cortex. Vibrations caused by moving air are translated by this part of the brain into perceptible sound information.

Exactly what these processes look like was still unknown in spite of the established understanding of the role played by the auditory cortex in the process of hearing. Thanks to some novel research techniques including 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 the facts they found are as follows: there are two parts of the auditory cortex that manage most of the work in allowing you to identify distinct voices. They’re what enables you to separate and intensify particular voices in loud environments.

  • Superior temporal gyrus (STG): The differentiated voices go from the HG to the STG, and it’s here that your brain starts to make some value distinctions. Which voices can be freely 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 region of the auditory cortex. Researchers found that the Heschl’s gyrus (we’re just going to call it HG from now on) was processing each unique voice, classifying them into individual identities.

When you have hearing loss, your ears are missing particular wavelengths so it’s harder for your brain to differentiate voices (low or high, depending on your hearing loss). Your brain isn’t supplied with enough information to assign individual identities to each voice. As a result, it all blends together (meaning interactions will harder to follow).

A New Algorithm From New Science

Hearing aids currently have functions that make it easier to hear in noisy environments. But now that we know what the fundamental process looks like, hearing aid manufacturers can integrate more of those natural functions into their device algorithms. For instance, you will have a greater ability to hear and understand what your coworkers are saying with hearing aids that help the Heshl’s gyrus and do a little more to differentiate voices.

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

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