Selective hearing is a phrase that normally gets tossed about as a pejorative, an insult. When your mother used to accuse you of having “selective hearing,” she was suggesting that you paid attention to the part about chocolate cake for dessert and (perhaps purposely) ignored the part about doing your chores.
But actually it takes an amazing act of cooperation between your brain and your ears to have selective hearing.
Hearing in a Crowd
Perhaps you’ve encountered this scenario before: you’re feeling burnt out from a long workday but your friends all really would like to go out for dinner and drinks. They decide on the loudest restaurant (because they have incredible food and live entertainment). And you strain and struggle to follow the conversation for the entire evening.
But it’s difficult, and it’s taxing. And it’s a sign of hearing loss.
You think, perhaps the restaurant was simply too noisy. But… everyone else appeared to be having a fine go of it. You seemed like the only one having trouble. Which gets you thinking: Why do ears that have hearing impairment have such a difficult time with the noise of a packed room? Why is it that being able to hear in a crowd is so challenging? Scientists have started to uncover the answer, and it all begins with 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 happen in your ears at all. This process nearly exclusively happens in your brain. At least, that’s in accordance with a new study carried out by a team at Columbia University.
Scientists have recognized for quite some time that human ears essentially work like a funnel: they compile all the impulses and then forward the raw data to your brain. That’s where the real work takes place, specifically the auditory cortex. Vibrations caused by moving air are translated by this part of the brain into perceptible sound information.
Because of comprehensive research with MRI and CT scans, scientists have understood for years that the auditory cortex plays a substantial role in hearing, but they were stumped when it came to what those processes really look like. Thanks to some unique research methods involving participants with epilepsy, scientists at Columbia were able to discover more about how the auditory cortex works in terms of picking out voices in a crowd.
The Hearing Hierarchy
And here’s what these intrepid scientists found: the majority of the work performed by the auditory cortex to isolate particular voices is done by two different regions. They’re what allows you to separate and enhance specific voices in loud environments.
- Superior temporal gyrus (STG): Sooner or later your brain will need to make some value based decisions and this occurs in the STG once it receives the voices that were previously separated by the HG. The superior temporal gyrus determines which voices you want to give attention to and which can be safely moved to the background.
- Heschl’s gyrus (HG): This is the region of the auditory cortex that manages the first phase of the sorting process. Researchers observed 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.
When you have hearing loss, your ears are lacking certain wavelengths so it’s more difficult for your brain to recognize voices (depending on your hearing loss it might be high or low frequencies). Your brain isn’t supplied with enough data to assign separate identities to each voice. It all blurs together as a result (which makes conversations tough to follow).
A New Algorithm From New Science
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 integrate more of those natural functions into their algorithms because they have a better concept of what the process looks like. For instance, hearing aids that do more to differentiate voices can assist the Heschl’s gyrus a little, bringing about a better capacity for you to understand what your coworkers are saying in that noisy restaurant.
Technology will get better at mimicking what takes place in nature as we learn more about how the brain works in conjunction with the ears. And better hearing success will be the result. Then you can concentrate a little more on enjoying yourself and a little less on straining to hear.