Selective hearing is a term that normally gets tossed about as a pejorative, an insult. Maybe you heard your mother suggest that your father had “selective hearing” when she suspected he might be ignoring her.
But actually it takes an amazing act of cooperation between your ears and your brain to have selective hearing.
Hearing in a Crowd
This scenario potentially feels familiar: you’ve had a long day at work, but your friends all insist on going out to dinner. And naturally, they want to go to the noisiest restaurant (because it’s popular and the deep-fried cauliflower is the best in town). And you spend an hour and a half straining your ears, trying to follow the conversation.
But it’s difficult, and it’s taxing. And it’s a sign of hearing loss.
You think, maybe the restaurant was just too loud. But… everyone else seemed to be having a fine go of it. The only person who appeared to be having difficulty was you. So you begin to ask yourself: Why do ears that have hearing impairment have such a hard time with the noise of a crowded room? Just why is it that being able to hear in a crowd is so quick to go? Scientists have started to uncover the solution, and it all starts with selective hearing.
How Does Selective Hearing Work?
The scientific name for what we’re broadly calling selective hearing is “hierarchical encoding,” and it doesn’t take place inside of your ears at all. This process almost exclusively takes place in your brain. At least, that’s in line with a new study performed by a team from Columbia University.
Scientists have recognized for some time that human ears essentially work as a funnel: they deliver all of the unprocessed data that they collect to your brain. That’s where the heavy lifting takes place, particularly the auditory cortex. Vibrations triggered by moving air are interpreted by this part of the brain into perceptible sound information.
Because of substantial research with MRI and CT scans, scientists have recognized for years that the auditory cortex plays a considerable role in hearing, but they were clueless when it came to what those processes really look like. Thanks to some novel research methods involving participants with epilepsy, scientists at Columbia were able to learn more about how the auditory cortex functions in relation to discerning voices in a crowd.
The Hearing Hierarchy
And here is what these intrepid scientists learned: most of the work accomplished by the auditory cortex to isolate specific voices is performed by two separate parts. They’re what enables you to sort and enhance distinct voices in noisy environments.
- Heschl’s gyrus (HG): The first sorting phase is taken care of by this part of the auditory cortex. Researchers discovered that the Heschl’s gyrus (we’re simply going to call it HG from here on out) was breaking down each unique voice, separating them via unique identities.
- Superior temporal gyrus (STG): At some point your brain needs to make some value based choices and this happens in the STG after it receives the voices that were previously differentiated by the HG. Which voices can be safely moved to the background and which ones you want to pay attention to is determined by the STG..
When you have hearing problems, your ears are lacking specific wavelengths so it’s more difficult for your brain to distinguish voices (high or low, depending on your hearing loss). Your brain isn’t given enough information to assign individual identities to each voice. As a result, it all blurs together (which means interactions will harder to follow).
A New Algorithm From New Science
Hearing aids currently have functions that make it easier to hear in noisy environments. But now that we know what the basic process looks like, hearing aid manufacturers can integrate more of those natural functions into their device algorithms. For instance, you will have a better ability to hear and understand what your coworkers are saying with hearing aids that assist the Heshl’s gyrus and do a little more to differentiate voices.
The more we understand about how the brain works, particularly in combination with the ears, the better new technology will be able to mimic what happens in nature. And that can result in better hearing success. That way, you can concentrate a little less on struggling to hear and a little more on enjoying yourself.