Why Can’t I Hear in a Crowd?

Man can't hear in a crowded restaurant.

Sometimes when an individual has a difficult time hearing, somebody close to them insultingly suggests they have “selective hearing”. Perhaps you heard your mother suggest that your father had “selective hearing” when she thought he was ignoring her.

But actually selective hearing is quite the ability, an impressive linguistic task executed by cooperation between your brain and ears.

Hearing in a Crowd

This scenario potentially feels familiar: you’re feeling tired 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 noisiest restaurant (because it’s popular and the deep-fried cauliflower is the best in town). And you strain and struggle to understand the conversation for over an hour and a half.

But it’s challenging, and it’s taxing. And it’s a sign of hearing loss.

You think, maybe the restaurant was just too noisy. But… everyone else appeared to be having a fine go of it. It seemed like you were the only one experiencing difficulty. Which makes you think: what is it about the crowded room, the cacophony of voices all struggling to be heard, that throws hearing-impaired ears for a loop? It seems as if hearing well in a crowded place is the first thing to go, but why? Scientists have begun to uncover the solution, and it all starts with selective hearing.

Selective Hearing – How Does it Work?

The phrase “selective hearing” is a process that doesn’t even occur in the ears and is technically known as “hierarchical encoding”. This process almost completely takes place 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 as scientists have understood for quite a while: they collect all the impulses and then forward the raw information to your brain. That’s where the heavy lifting happens, particularly the auditory cortex. That’s the part of your gray matter that processes all those impulses, interpreting impressions of moving air into recognizable sounds.

Because of comprehensive 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 when it came to what those processes really look like. Thanks to some novel research methods involving participants with epilepsy, scientists at Columbia were able to learn more about how the auditory cortex functions in terms of discerning voices in a crowd.

The Hierarchy of Hearing

And the facts they discovered are as follows: most of the work accomplished by the auditory cortex to isolate particular voices is done by two separate regions. They’re what allows you to sort and amplify specific voices in loud situations.

  • Heschl’s gyrus (HG): The first sorting stage is managed by this part of the auditory cortex. Researchers observed that the Heschl’s gyrus (we’re simply going to call it HG from now on) was processing each individual voice, classifying them via unique identities.
  • Superior temporal gyrus (STG): The differentiated voices move from the HG to the STG, and it’s here that your brain starts to make some value determinations. The superior temporal gyrus figures out which voices you want to pay attention to and which can be securely moved to the background.

When you have hearing problems, your ears are lacking certain wavelengths so it’s harder for your brain to recognize voices (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. It all blends together as a consequence (which means conversations will more difficult to follow).

New Science = New Algorithm

Hearing aids already have functions that make it easier to hear in noisy environments. But now that we know what the basic process looks like, hearing aid companies can incorporate more of those natural functions into their device algorithms. For instance, hearing aids that do more to differentiate voices can assist the Heschl’s gyrus a little bit, resulting in a better capacity for you to comprehend what your coworkers are talking about in that loud restaurant.

The more we understand about how the brain works, particularly in connection with the ears, the better new technology will be able to mimic what happens in nature. And that can lead to better hearing outcomes. That way, you can focus a little less on struggling to hear and a little more on enjoying yourself.

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