Man can't hear in a crowded restaurant.

Sometimes when an individual has a hard time hearing, someone close to them insultingly says they have “selective hearing”. Maybe you heard your mother accuse your father of having “selective hearing” when she suspected he was ignoring her.

But it turns out that selective hearing is quite the talent, an amazing linguistic task performed by teamwork between your brain and ears.

The Stress Of Trying to Hear in a Crowd

Perhaps you’ve experienced this situation before: you’ve been through a long day at work, but your friends all insist on going out to dinner. They pick the noisiest 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 difficult, and it’s taxing. This suggests that you may have hearing loss.

Perhaps, you rationalize, the restaurant was just too noisy. But no one else appeared to be having difficulties. It seemed like you were the only one experiencing difficulty. Which gets you thinking: Why do ears with hearing impairment have such a difficult time with the noise of a crowded room? It seems as if hearing well in a crowded place is the first thing to go, but what’s the reason? Scientists have started to discover the answer, and it all starts with selective hearing.

How Does Selective Hearing Work?

The phrase “selective hearing” is a process that doesn’t even occur in the ears and is formally known as “hierarchical encoding”. Most of this process occurs in the brain. At least, that’s in accordance with a new study carried out by a team from Columbia University.

Ears work just like a funnel as scientists have understood for quite a while: they collect all the signals and then send the raw data to your brain. In the auditory cortex the real work is then accomplished. Vibrations triggered by moving air are interpreted by this part of the brain into recognizable sound information.

Exactly what these processes look like had remained a mystery in spite of the established understanding of the role played by the auditory cortex in the hearing process. Thanks to some unique research methods involving participants with epilepsy, scientists at Columbia were able to discover more about how the auditory cortex works in relation to picking out voices in a crowd.

The Hearing Hierarchy

And here is what these intrepid scientists learned: most of the work done by the auditory cortex to pick out particular voices is performed by two different parts. And in loud situations, they allow you to isolate and intensify certain voices.

  • Superior temporal gyrus (STG): The separated voices move from the HG to the STG, and it’s at this point that your brain begins to make some value determinations. Which voices can be comfortably moved to the background and which ones you want to focused on is figured out by the STG..
  • Heschl’s gyrus (HG): The first sorting phase is taken care of by this region of the auditory cortex. Heschl’s gyrus or HG processes each unique voice and separates them into discrete identities.

When you have hearing loss, your ears are missing particular wavelengths so it’s more difficult for your brain to recognize voices (depending on your hearing loss it might be high or low frequencies). Your brain isn’t provided with enough information to assign individual identities to each voice. It all blurs together as a result (meaning discussions will harder to understand).

New Science = New Algorithm

Hearing aids already have features that make it easier to hear in loud settings. But hearing aid makers can now incorporate more of those natural functions into their algorithms because they have a better idea of what the process looks like. As an example, hearing aids that do more to differentiate voices can assist the Heschl’s gyrus a little bit, bringing about a greater capacity for you to understand what your coworkers are saying in that noisy restaurant.

The more we learn about how the brain works, particularly in combination with the ears, the better new technology will be capable of mimicking what happens in nature. And better hearing success will be the result. That way, you can focus a little less on straining to hear and a little more on enjoying yourself.

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