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 listened to the part about going to the fair and (perhaps intentionally) ignored the bit about doing your chores.

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

Hearing in a Crowd

Maybe you’ve dealt with this scenario before: you’re feeling tired from a long day at work but your friends all really want to go out for dinner and drinks. They pick the noisiest restaurant (because they have great food and live entertainment). And you strain and struggle to follow the conversation for the entire evening.

But it’s tough, and it’s taxing. And it’s a sign of hearing loss.

You think, maybe the restaurant was simply too noisy. But… everyone else appeared to be having a great time. The only one who appeared to be having difficulty was you. So you start to wonder: what is it about the packed room, the cacophony of voices all trying to be heard, that throws hearing-impaired ears for a loop? Just why is it that being able to hear in a crowd is so quick to go? Scientists have begun to discover the solution, 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 formally called “hierarchical encoding”. The majority of this process occurs in the brain. At least, that’s in line with a new study done by a team at Columbia University.

Ears work just like a funnel as scientists have understood for some time: they compile all the impulses and then send the raw information to your brain. In the auditory cortex the real work is then accomplished. That’s the part of your brain that handles all those signals, interpreting sensations of moving air into perceptible sounds.

Just what these processes look like had remained a mystery in spite of the established knowledge 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 learn more about how the auditory cortex functions when it comes to discerning voices in a crowd.

The Hearing Hierarchy

And here is what these intrepid scientists discovered: there are two regions of the auditory cortex that manage most of the work in allowing you to key in on specific voices. They’re what allows you to separate and enhance particular voices in loud environments.

  • Superior temporal gyrus (STG): Sooner or later your brain needs to make some value based decisions and this happens in the STG once it receives the voices which 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..
  • Heschl’s gyrus (HG): This is the region of the auditory cortex that deals with the first phase of the sorting process. Heschl’s gyrus or HG breaks down each unique voice and separates them into discrete identities.

When you have hearing loss, your ears are missing certain wavelengths so it’s more difficult for your brain to differentiate voices (depending on your hearing loss it could be high or low frequencies). Your brain isn’t supplied with enough data to assign individual identities to each voice. It all blends together as a consequence (meaning interactions will harder to understand).

A New Algorithm From New Science

Hearing aids currently have functions that make it easier to hear in loud settings. But now that we understand what the fundamental process looks like, hearing aid makers can integrate more of those natural operations into their instrument algorithms. For instance, hearing aids that do more to identify voices can assist the Heschl’s gyrus a little bit, leading to a greater capacity for you to understand what your coworkers are talking about in that loud restaurant.

Technology will get better at mimicking what happens in nature as we uncover more about how the brain really works in combination with the ears. And better hearing outcomes will be the result. That way, you can focus a little less on struggling to hear and a little more on enjoying yourself.