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Man can't hear in a crowded restaurant.

Selective hearing is a phrase that frequently is used as a pejorative, an insult. Maybe you heard your mother suggest that your father had “selective hearing” when she believed he might be ignoring her.

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

Hearing in a Crowd

Perhaps you’ve dealt with this situation before: you’ve had a long day at work, but your buddies all insist on going out to dinner. And of course, they want to go to the loudest restaurant (because it’s popular and the deep-fried cauliflower is the best in town). And you spend an hour and a half straining your ears, attempting to follow the conversation.

But it’s very difficult and exhausting. And it’s an indication of hearing loss.

You think, maybe the restaurant was simply too noisy. But no one else appeared to be having difficulties. The only one who appeared to be having trouble was you. Which makes you think: Why do ears with 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 uncover the answer, and it all starts with selective hearing.

Selective Hearing – How Does it Work?

The scientific name for what we’re broadly calling selective hearing is “hierarchical encoding,” and it doesn’t happen inside of your ears at all. This process nearly entirely takes place in your brain. At least, that’s in line with a new study performed by a team at Columbia University.

Ears work like a funnel which scientists have known for quite a while: they send all of the raw data that they gather to your brain. In the auditory cortex the real work is then accomplished. Vibrations triggered by moving air are interpreted by this portion of the brain into perceptible sound information.

Just what these processes look like had remained a mystery in spite of the existing knowledge of the role played by the auditory cortex in the process of hearing. Scientists were able, by utilizing unique research techniques on individuals with epilepsy, to get a better picture of how the auditory cortex picks out voices in a crowd.

The Hearing Hierarchy

And the information they found out are as follows: the majority of the work done by the auditory cortex to pick out particular voices is accomplished by two different regions. They’re what allows you to sort and enhance distinct voices in loud settings.

  • Superior temporal gyrus (STG): The differentiated voices move from the HG to the STG, and it’s at this point that your brain starts to make some value determinations. Which voices can be comfortably moved to the background and which ones you want to pay attention to is figured out by the STG..
  • Heschl’s gyrus (HG): This is the region of the auditory cortex that manages the first stage of the sorting process. Scientists discovered that the Heschl’s gyrus (we’re simply going to call it HG from here on out) was processing each individual voice, separating them into individual identities.

When you start to suffer from hearing problems, it’s more difficult for your brain to differentiate voices because your ears are missing specific wavelengths of sound (depending on your hearing loss it might be high or low frequencies). Your brain can’t assign separate identities to each voice because it doesn’t have enough information. Consequently, it all blurs together (which makes interactions tough to follow).

New Science = New Algorithm

Hearing aids already have functions that make it less difficult to hear in noisy environments. But now that we know what the basic process looks like, hearing aid manufacturers can integrate more of those natural functions into their device algorithms. As an example, hearing aids that do more to differentiate voices can help out the Heschl’s gyrus a little, resulting in a better capacity for you to understand what your coworkers are saying in that loud restaurant.

Technology will get better at mimicking what takes place in nature as we learn more about how the brain really works in combination with the ears. And that can lead to improved hearing success. Then you can focus a little more on enjoying yourself and a little less on straining to hear.

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