Selective hearing is a phrase that normally is used as a pejorative, an insult. Maybe you heard your mother accuse your father of having “selective hearing” when she thought he was ignoring her.
But it turns out that selective hearing is quite the skill, an impressive linguistic feat executed by teamwork between your brain and ears.
The Stress Of Trying to Hear in a Crowd
This scenario probably feels familiar: you’ve been through a long day at work, but your buddies all insist on meeting up for dinner. And of course, they want to go to the noisiest restaurant (because it’s trendy and the deep-fried cauliflower is delicious). And you strain and struggle to follow the conversation for the entire evening.
But it’s very difficult and exhausting. And it’s a sign of hearing loss.
Maybe, you rationalize, the restaurant was simply too loud. But… everyone else seemed to be having a great time. You seemed like the only one having trouble. So you start to ask yourself: what is it about the crowded room, the cacophony of voices all battling to be heard, that throws hearing-impaired ears for a loop? Why is it that being able to hear in a crowd is so challenging? The answer, as reported by scientists, is selective hearing.
How Does Selective Hearing Operate?
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 almost completely occurs in your brain. At least, that’s as reported by a new study done by a team at Columbia University.
Scientists have recognized for quite a while that human ears essentially work like a funnel: they compile all the impulses and then deliver the raw information to your brain. That’s where the real work takes place, particularly the auditory cortex. Vibrations caused by moving air are translated by this portion of the brain into perceptible sound information.
Because of substantial research with CT and MRI scans, scientists have understood for years that the auditory cortex plays a crucial role in hearing, but they were stumped when it came to what those processes actually look like. Scientists were able, by making use of novel 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 the insight they discovered are as follows: there are two components of the auditory cortex that accomplish most of the work in helping you identify individual voices. They’re what allows you to sort and amplify particular voices in loud situations.
- Heschl’s gyrus (HG): The first sorting stage is handled by this part of the auditory cortex. Scientists found that the Heschl’s gyrus (we’re simply going to call it HG from here on out) was processing each unique voice, classifying them via unique identities.
- Superior temporal gyrus (STG): The separated voices move from the HG to the STG, and it’s here that your brain starts to make some value distinctions. The superior temporal gyrus figures out which voices you want to give attention to and which can be safely moved to the background.
When you have hearing loss, your ears are missing certain wavelengths so it’s harder for your brain to recognize voices (depending on your hearing loss it could be low or high frequencies). Your brain isn’t given enough data to assign individual identities to each voice. As a result, it all blurs together (which makes discussions difficult to follow).
New Science = New Algorithm
Hearing aids already have functions that make it less difficult to hear in loud environments. But hearing aid makers can now integrate more of those natural functions into their algorithms because they have a greater idea of what the process looks like. For instance, you will have a greater ability to hear and understand what your coworkers are saying with hearing aids that help the Heshl’s gyrus and do a little more to differentiate voices.
The more we find out about how the brain works, especially in connection with the ears, the better new technology will be able to mimic what takes place in nature. And that can result in better hearing success. That way, you can focus a little less on struggling to hear and a little more on enjoying yourself.