Why Can’t I Hear in a Crowd?

Man can't hear in a crowded restaurant.

Sometimes when an individual has a hard time hearing, somebody close to them insultingly suggests they have “selective hearing”. When your mother used to accuse you of having “selective hearing,” she was suggesting that you paid attention to the part about going to the fair and (maybe intentionally) ignored the part about doing your chores.

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

Hearing in a Crowd

This scenario probably feels familiar: you’ve had a long day at work, but your buddies all insist on going out to dinner. They choose 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, working hard to follow the conversation.

But it’s tough, and it’s taxing. And it’s an indication of hearing loss.

You think, perhaps the restaurant was simply too loud. But no one else seemed to be having difficulties. The only person who appeared to be having difficulty was you. Which gets you thinking: what is it about the crowded room, the cacophony of voices all battling to be heard, that throws hearing-impaired ears for a loop? It seems like hearing well in a crowded place is the first thing to go, but what’s the reason? Scientists have begun to reveal the answer, and it all begins with selective hearing.

How Does Selective Hearing Function?

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

Scientists have known for some time that human ears basically work as a funnel: they compile all the signals and then send the raw data to your brain. In the auditory cortex the real work is then done. Vibrations caused by moving air are translated by this portion of the brain into recognizable sound information.

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 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 Hierarchy of Hearing

And here’s what these intrepid scientists found out: the majority of the work done by the auditory cortex to isolate particular voices is done by two different regions. And in loud settings, they enable you to separate and amplify 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 observed that the Heschl’s gyrus (we’re just going to call it HG from now on) was breaking down each distinct voice, classifying them via unique identities.
  • Superior temporal gyrus (STG): At some point your brain needs to make some value based decisions and this happens in the STG once it receives the voices which were previously differentiated by the HG. Which voices can be freely moved to the background and which ones you want to focused on is determined by the STG..

When you begin to suffer from hearing impairment, it’s harder for your brain to differentiate voices because your ears are lacking certain wavelengths of sound (depending on your hearing loss it might be high or low frequencies). Your brain isn’t furnished with enough information to assign individual identities to each voice. It all blurs together as a consequence (which makes discussions tough to follow).

A New Algorithm From New Science

Hearing aids currently have features that make it easier to hear in loud situations. But hearing aid manufacturers can now incorporate more of those natural functions into their algorithms because they have a greater concept of what the process looks like. As an example, hearing aids that do more to distinguish voices can help out the Heschl’s gyrus a little bit, resulting in a better ability for you to understand what your coworkers are talking about in that noisy restaurant.

The more we find out about how the brain works, specifically in combination with the ears, the better new technology will be capable of mimicking what takes place in nature. 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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