Man can't hear in a crowded restaurant.

Selective hearing is a term that usually gets tossed about as a pejorative, an insult. When your mother used to accuse you of having “selective hearing,” she meant that you paid attention to the part about chocolate cake for dessert and (perhaps purposely) disregarded the part about cleaning your room.

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

The Stress Of Trying to Hear in a Crowd

This situation probably seems familiar: you’re feeling tired from a long day at work but your friends all really would like to go out for dinner and drinks. They pick the loudest restaurant (because it’s trendy and the food is the best in town). And you strain and struggle to understand the conversation for over an hour and a half.

But it’s difficult, and it’s taxing. This suggests that you might have hearing loss.

You think, perhaps the restaurant was simply too loud. But no one else appeared to be having difficulties. The only one who appeared to be having trouble was you. Which makes you think: what is it about the crowded room, the cacophony of voices all struggling to be heard, that causes hearing impaired ears to struggle? 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 reveal the answer, and it all begins with selective hearing.

Selective Hearing – How Does it Work?

The term “selective hearing” is a task that doesn’t even occur in the ears and is scientifically known as “hierarchical encoding”. The majority of this process occurs in the brain. At least, that’s in line with a new study performed by a team at Columbia University.

Scientists have known for quite a while that human ears essentially work like a funnel: they collect all the signals and then forward the raw information to your brain. In the auditory cortex the real work is then done. That’s the part of your gray matter that processes all those signals, interpreting sensations of moving air into perceptible sounds.

Just what these processes look like was still unknown in spite of the existing understanding of the role played by the auditory cortex in the process of hearing. Thanks to some innovative research techniques including participants with epilepsy, scientists at Columbia were able to discover more about how the auditory cortex works in terms of discerning voices in a crowd.

The Hierarchy of Hearing

And here is what these intrepid scientists found out: there are two parts of the auditory cortex that accomplish most of the work in allowing you to key in on distinct voices. And in loud settings, they allow you to isolate and boost particular voices.

  • Heschl’s gyrus (HG): The first sorting phase is handled by this part of the auditory cortex. Scientists observed that the Heschl’s gyrus (we’re just going to call it HG from now on) was processing each unique voice, classifying them into unique identities.
  • Superior temporal gyrus (STG): Sooner or later your brain needs to make some value based choices and this is done in the STG once it receives the voices that were previously separated by the HG. Which voices can be safely moved to the background and which ones you want to focused on is determined by the STG..

When you have hearing impairment, your ears are missing specific wavelengths so it’s more difficult for your brain to distinguish voices (low or high, depending on your hearing loss). Your brain isn’t given enough information to assign individual identities to each voice. Consequently, it all blurs together (meaning conversations will harder to understand).

New Science = New Algorithm

It’s typical for hearing aids to come with features that make it easier to hear in a crowded situation. But now that we understand what the basic process looks like, hearing aid manufacturers can integrate more of those natural operations into their instrument algorithms. For instance, hearing aids that do more to distinguish voices can help out the Heschl’s gyrus a little bit, resulting in a greater capacity for you to understand what your coworkers are saying in that loud restaurant.

Technology will get better at mimicking what happens in nature as we discover more about how the brain works in conjunction with the ears. And that can lead to better hearing success. That way, you can focus a little less on struggling to hear and a little more on enjoying yourself.