Why Can’t I Hear in a Crowd?

Man can't hear in a crowded restaurant.

Selective hearing is a term that frequently 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 going to the fair and (perhaps purposely) disregarded the bit about doing your chores.

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

The Stress Of Trying to Hear in a Crowd

This situation probably seems familiar: you’ve had a long day at work, but your friends all insist on meeting up for dinner. They choose the loudest restaurant (because it’s popular and the deep-fried cauliflower is delicious). And you strain and struggle to understand the conversation for the entire evening.

But it’s difficult, and it’s taxing. This indicates that you could have hearing loss.

Perhaps, you rationalize, the restaurant was simply too noisy. But no one else appeared to be struggling. You seemed like the only one experiencing trouble. Which makes you think: Why do ears that have hearing impairment have such a difficult time with the noise of a crowded room? Why is it that being able to hear in a crowd is so challenging? The solution, as reported by scientists, is selective hearing.

How Does Selective Hearing Function?

The phrase “selective hearing” is a process that doesn’t even happen in the ears and is formally known as “hierarchical encoding”. This process almost 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 known for some time that human ears essentially work as a funnel: they deliver all of the raw data that they collect to your brain. In the auditory cortex the real work is then accomplished. That’s the part of your brain that processes all those impulses, translating impressions of moving air into identifiable sounds.

Precisely 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. Scientists were able, by making use of 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 here’s what these intrepid scientists discovered: the majority of the work accomplished by the auditory cortex to isolate distinct voices is done by two separate parts. And in loud environments, they enable you to separate and enhance specific voices.

  • Superior temporal gyrus (STG): The differentiated voices move from the HG to the STG, and it’s at this point that your brain begins to make some value determinations. The superior temporal gyrus determines which voices you want to give attention to and which can be confidently moved to the background.
  • Heschl’s gyrus (HG): This is the part of the auditory cortex that handles the first stage of the sorting process. Heschl’s gyrus or HG processes each unique voice and separates them into distinct identities.

When you start to suffer from hearing damage, it’s more difficult for your brain to identify voices because your ears are lacking certain wavelengths of sound (low or high, based upon your hearing loss). Your brain can’t assign separate identities to each voice because it doesn’t have enough data. It all blurs together as a result (which means conversations will harder to understand).

A New Algorithm From New Science

It’s standard for hearing aids to have functions that make it easier to hear in a crowd. But now that we understand what the fundamental process looks like, hearing aid manufacturers can incorporate more of those natural operations into their instrument algorithms. For example, hearing aids that do more to distinguish voices can assist the Heschl’s gyrus a little bit, leading to a better capacity for you to comprehend what your coworkers are talking about in that loud restaurant.

Technology will get better at mimicking what occurs in nature as we learn more about how the brain works in conjunction with the ears. And better hearing outcomes will be the result. Then you can focus a little more on enjoying yourself and a little less on straining to hear.

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