Man can't hear in a crowded restaurant.

Selective hearing is a term that frequently gets tossed about as a pejorative, an insult. Maybe you heard your mother suggest that your father had “selective hearing” when she thought he might be ignoring her.

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

Hearing in a Crowd

Perhaps you’ve dealt with this scenario before: 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 trendy and the deep-fried cauliflower is the best in town). And you spend an hour and a half straining your ears, trying to follow the conversation.

But it’s tough, and it’s taxing. 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 one who appeared to be having difficulty was you. Which gets you thinking: 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 begins with selective hearing.

How Does Selective Hearing Operate?

The term “selective hearing” is a process that doesn’t even take place in the ears and is scientifically called “hierarchical encoding”. Most of this process happens in the brain. At least, that’s as reported by a new study performed by a team from Columbia University.

Scientists have recognized for some time that human ears basically work like a funnel: they compile all the signals and then send the raw information to your brain. That’s where the heavy lifting takes place, particularly the auditory cortex. That’s the part of your gray matter that handles all those impulses, translating impressions of moving air into recognizable sounds.

Exactly what these processes look like was still unknown despite the established understanding of the role played by the auditory cortex in the hearing process. Scientists were able, by utilizing unique research techniques on individuals with epilepsy, to get a better picture of how the auditory cortex discerns voices in a crowd.

The Hearing Hierarchy

And here’s what these intrepid scientists found: most of the work accomplished by the auditory cortex to pick out specific voices is performed by two separate parts. And in loud conditions, they enable you to separate and enhance specific voices.

  • Heschl’s gyrus (HG): This is the part of the auditory cortex that deals with the first phase of the sorting process. Researchers found that the Heschl’s gyrus (we’re just going to call it HG from now on) was breaking down each unique voice, classifying them via individual identities.
  • Superior temporal gyrus (STG): The differentiated voices move from the HG to the STG, and it’s here that your brain begins to make some value determinations. The superior temporal gyrus determines which voices you want to pay attention to and which can be confidently moved to the background.

When you start to suffer with hearing damage, it’s more difficult for your brain to identify voices because your ears are missing particular wavelengths of sound (low or high, based upon your hearing loss). Your brain can’t assign individual identities to each voice because it doesn’t have enough information. Consequently, it all blends together (which makes interactions difficult to follow).

New Science = New Algorithm

It’s common for hearing aids to have functions that make it less difficult to hear in a crowded situation. But now that we know what the fundamental process looks like, hearing aid makers can incorporate more of those natural functions into their device algorithms. For example, you will have a better ability to hear and comprehend what your coworkers are saying with hearing aids that help the Heshl’s gyrus and do a little more to distinguish voices.

The more we learn about how the brain works, particularly in connection with the ears, the better new technology will be able to mimic what takes place in nature. And better hearing outcomes 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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