Selective hearing is a term that commonly gets tossed about as a pejorative, an insult. When your mother used to accuse you of having “selective hearing,” she meant that you listened to the part about going to the fair and (maybe purposely) disregarded the bit about doing your chores.
But it turns out that selective hearing is quite the talent, an amazing linguistic feat performed by cooperation between your brain and ears.
The Stress Of Trying to Hear in a Crowd
This situation probably seems familiar: you’re feeling burnt out from a long workday but your friends all really would like to go out for dinner and drinks. They choose the noisiest restaurant (because it’s popular and the deep-fried cauliflower is the best in town). And you strain and struggle to follow the conversation for the entire evening.
But it’s very difficult and exhausting. This suggests that you could have hearing loss.
Maybe, you rationalize, the restaurant was simply too loud. But… everyone else appeared to be having a great time. You seemed like the only one experiencing trouble. So you start to wonder: what is it about the crowded room, the cacophony of voices all trying 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 why? Scientists have begun to uncover the answer, and it all starts with selective hearing.
How Does Selective Hearing Function?
The scientific name for what we’re loosely calling selective hearing is “hierarchical encoding,” and it doesn’t take place inside of your ears at all. This process nearly exclusively takes place in your brain. At least, that’s in accordance with a new study carried out by a team at Columbia University.
Scientists have known for quite some time that human ears essentially work as a funnel: they collect all the impulses and then forward the raw information to your brain. That’s where the real work takes place, particularly the auditory cortex. Vibrations caused by moving air are interpreted by this part of the brain into perceptible sound information.
Exactly what these processes look like had remained a mystery despite the existing knowledge of the role played by the auditory cortex in the hearing process. Thanks to some novel research methods concerning participants with epilepsy, scientists at Columbia were able to learn more about how the auditory cortex works in terms of discerning voices in a crowd.
The Hierarchy of Hearing
And the facts they found out follows: there are two parts of the auditory cortex that manage most of the work in allowing you to identify particular voices. And in noisy environments, they allow you to separate and amplify certain voices.
- Superior temporal gyrus (STG): Sooner or later your brain will need to make some value based decisions and this happens in the STG once it receives the voices which were previously differentiated by the HG. The superior temporal gyrus figures out which voices you want to pay attention to and which can be safely moved to the background.
- Heschl’s gyrus (HG): The first sorting phase is managed by this part of the auditory cortex. Heschl’s gyrus or HG breaks down each individual voice and separates them into distinguishable identities.
When you begin to suffer from hearing problems, it’s more difficult for your brain to differentiate voices because your ears are lacking particular wavelengths of sound (depending on your hearing loss it might be high or low frequencies). Your brain isn’t furnished with enough data to assign separate identities to each voice. It all blends together as a consequence (which means discussions will harder to follow).
New Science = New Algorithm
It’s standard for hearing aids to come with features that make it easier 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 concept of what the process looks like. As an example, you will have a better ability to hear and understand what your coworkers are talking about with hearing aids that help the Heshl’s gyrus and do a little more to separate voices.
The more we discover about how the brain works, particularly in conjunction with the ears, the better new technology will be able to mimic what happens 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.