Selective hearing is a phrase that frequently is used 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 (maybe purposely) disregarded the part about doing your chores.

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

Hearing in a Crowd

This situation probably seems familiar: you’ve been through a long day at work, but your friends all insist on going out to dinner. They choose the noisiest restaurant (because they have great food and live entertainment). And you spend an hour and a half straining your ears, working hard to follow the conversation.

But it’s very difficult and exhausting. This indicates that you may have hearing loss.

You think, maybe the restaurant was just too loud. But… everyone else appeared to be having a great time. It seemed like you were the only one experiencing difficulty. So you start to wonder: 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 crowd is the first thing to go, but what’s the reason? The solution, as reported by scientists, is selective hearing.

How Does Selective Hearing Work?

The scientific term 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 completely occurs in your brain. At least, that’s as reported by a new study carried out by a team from Columbia University.

Ears work like a funnel which scientists have recognized for some time: they gather all the signals and then forward the raw data to your brain. That’s where the heavy lifting happens, specifically the auditory cortex. That’s the part of your brain that processes all those impulses, interpreting sensations of moving air into recognizable sounds.

Because of comprehensive research with CT and MRI scans, scientists have known for years that the auditory cortex plays a significant role in hearing, but they were stumped when it came to what those processes really look like. Thanks to some unique research techniques including participants with epilepsy, scientists at Columbia were able to discover more about how the auditory cortex works when it comes to discerning voices in a crowd.

The Hearing Hierarchy

And the insight they found out follows: there are two components of the auditory cortex that manage most of the work in allowing you to key in on particular voices. And in noisy environments, they allow you to separate and boost certain voices.

• Heschl’s gyrus (HG): The first sorting phase is managed by this region of the auditory cortex. Heschl’s gyrus or HG breaks down each individual voice and separates them into distinct 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 differentiated by the HG. The superior temporal gyrus figures out which voices you want to pay attention to and which can be confidently moved to the background.

When you begin to suffer from hearing problems, it’s more difficult for your brain to distinguish voices because your ears are missing certain wavelengths of sound (high or low, based upon your hearing loss). Your brain can’t assign individual identities to each voice because it doesn’t have enough data. Consequently, it all blends together (meaning discussions will more difficult to follow).

A New Algorithm From New Science

It’s typical for hearing aids to have functions that make it less difficult to hear in a crowded situation. But hearing aid manufacturers can now include more of those natural functions into their algorithms because they have a greater idea of what the process looks like. For instance, hearing aids that do more to distinguish voices can assist the Heschl’s gyrus a little bit, leading to a better ability for you to comprehend what your coworkers are saying in that noisy restaurant.

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