Hearing Health Blog

Man can't hear in a crowded restaurant.

Selective hearing is a term that normally is used 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 (perhaps deliberately) ignored the bit about cleaning your room.

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

The Stress Of Trying to Hear in a Crowd

Maybe you’ve experienced 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 food is delicious). And you spend an hour and a half straining your ears, working hard to follow the conversation.

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

Perhaps, you rationalize, the restaurant was simply too noisy. But no one else appeared to be having difficulties. The only one who appeared to be having difficulty was you. So you begin to ask yourself: Why do ears that have hearing impairment have such a hard time with the noise of a crowded room? Why is it that being able to hear in a crowd is so challenging? Scientists have started to uncover the solution, and it all begins with selective hearing.

How Does Selective Hearing Function?

The phrase “selective hearing” is a process that doesn’t even occur in the ears and is formally known as “hierarchical encoding”. This process nearly completely occurs in your brain. At least, that’s in line with a new study carried out by a team at Columbia University.

Scientists have recognized for some time that human ears effectively work as a funnel: they forward all of the raw data that they gather to your brain. That’s where the heavy lifting takes place, specifically the auditory cortex. Vibrations triggered by moving air are translated by this portion of the brain into recognizable sound information.

Just what these processes look like was still unknown in spite of the established understanding of the role played by the auditory cortex in the hearing process. Thanks to some unique research methods concerning participants with epilepsy, scientists at Columbia were able to discover more about how the auditory cortex functions in relation to picking out voices in a crowd.

The Hierarchy of Hearing

And the insight they found are as follows: there are two parts of the auditory cortex that accomplish most of the work in helping you identify distinct voices. And in noisy settings, they enable you to isolate and amplify certain voices.

  • Heschl’s gyrus (HG): The first sorting phase is handled by this part 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, separating them via unique identities.
  • Superior temporal gyrus (STG): Sooner or later your brain will need to make some value based decisions and this occurs in the STG once it receives the voices that were previously separated by the HG. The superior temporal gyrus figures out which voices you want to give attention to and which can be securely moved to the background.

When you start to suffer with hearing impairment, 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 could be low or high frequencies). Your brain can’t assign individual identities to each voice because it doesn’t have enough data. It all blurs together as a result (meaning interactions will harder to follow).

A New Algorithm From New Science

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

The more we understand about how the brain works, especially in connection with the ears, the better new technology will be able to mimic what takes place in nature. And better hearing success will be the outcome. Then you can concentrate a little more on enjoying yourself and a little less on straining to hear.

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