Selective hearing is a phrase 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 deliberately) disregarded the part about doing your chores.
But actually selective hearing is quite the talent, an amazing linguistic task performed by cooperation between your brain and ears.
Hearing in a Crowd
Perhaps you’ve encountered this scenario before: you’ve had a long day at work, but your friends all insist on meeting up for dinner. They pick the noisiest restaurant (because they have incredible food and live entertainment). And you spend the entire evening straining your ears, trying to follow the conversation.
But it’s tough, and it’s taxing. And it’s an indication of hearing loss.
You think, maybe the restaurant was simply too loud. But… everyone else appeared to be having a fine go of it. The only person who appeared to be having difficulty was you. So you start to ask yourself: what is it about the packed 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? Scientists have begun to reveal the answer, and it all starts with selective hearing.
Selective Hearing – How Does it Work?
The term “selective hearing” is a process that doesn’t even happen in the ears and is scientifically known as “hierarchical encoding”. This process almost exclusively takes place in your brain. At least, that’s according to a new study done by a team from Columbia University.
Ears work like a funnel which scientists have known for some time: they forward all of the unprocessed data that they collect to your brain. That’s where the heavy lifting occurs, specifically the auditory cortex. That’s the part of your gray matter that handles all those impulses, translating sensations of moving air into identifiable sounds.
Because of significant research with MRI and CT scans, scientists have understood for years that the auditory cortex plays a substantial role in hearing, but they were clueless regarding what those processes actually look like. Thanks to some innovative research methods involving participants with epilepsy, scientists at Columbia were able to learn more about how the auditory cortex works when it comes to picking out voices in a crowd.
The Hearing Hierarchy
And the information they found are as follows: most of the work performed by the auditory cortex to isolate specific voices is performed by two different regions. They’re what allows you to separate and amplify specific voices in loud settings.
- Heschl’s gyrus (HG): This is the region of the auditory cortex that deals with the first stage of the sorting routine. Researchers found that the Heschl’s gyrus (we’re simply going to call it HG from now on) was breaking down each distinct voice, separating them into individual identities.
- Superior temporal gyrus (STG): The separated voices go from the HG to the STG, and it’s here that your brain begins to make some value determinations. Which voices can be freely moved to the background and which ones you want to focused on is determined by the STG..
When you have hearing impairment, your ears are missing particular wavelengths so it’s harder for your brain to distinguish voices (high or low, depending on your hearing loss). Your brain can’t assign separate identities to each voice because it doesn’t have enough data. It all blurs together as a consequence (which makes conversations hard to follow).
New Science = New Algorithm
Hearing aids already have functions that make it easier to hear in noisy environments. But hearing aid manufacturers can now integrate 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 greater capacity to hear and comprehend what your coworkers are saying with hearing aids that assist the Heshl’s gyrus and do a little more to separate voices.
Technology will get better at mimicking what happens in nature as we uncover more about how the brain really works in combination with the ears. And better hearing outcomes will be the result. That way, you can concentrate a little less on struggling to hear and a little more on enjoying yourself.
