Sometimes when an individual has a difficult time hearing, somebody close to them insultingly suggests they have “selective hearing”. When your mother used to accuse you of having “selective hearing,” she was suggesting that you listened to the part about going to the fair and (maybe intentionally) disregarded the part about cleaning your room.
But actually selective hearing is quite the ability, an amazing linguistic accomplishment performed by cooperation between your ears and brain.
Hearing in a Crowd
Maybe you’ve experienced this scenario before: you’re feeling tired from a long day at work but your friends all really want to go out for dinner and drinks. And naturally, they want to go to the loudest restaurant (because they have amazing food and live entertainment). And you spend an hour and a half straining your ears, working hard to follow the conversation.
But it’s difficult, and it’s taxing. And it’s a sign of hearing loss.
You think, perhaps the restaurant was simply too loud. But no one else seemed to be struggling. It seemed like you were the only one experiencing trouble. So you begin to ask yourself: what is it about the crowded room, the cacophony of voices all struggling to be heard, that throws hearing-impaired ears for a loop? It seems as if hearing well in a crowd is the first thing to go, but what’s the reason? Scientists have begun to uncover the solution, 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”. The majority of this process occurs in the brain. At least, that’s in accordance with a new study done by a team from Columbia University.
Ears work just like a funnel as scientists have understood for some time: they collect all the signals and then send the raw data to your brain. In the auditory cortex the real work is then done. That’s the part of your brain that processes all those impulses, translating impressions of moving air into perceptible sounds.
Because of substantial research with MRI and CT scans, scientists have understood for years that the auditory cortex plays a considerable role in hearing, but they were clueless with regards to what those processes actually look like. Thanks to some unique research techniques involving participants with epilepsy, scientists at Columbia were able to discover more about how the auditory cortex works in relation to picking out voices in a crowd.
The Hierarchy of Hearing
And here is what these intrepid scientists found: there are two components of the auditory cortex that do most of the work in allowing you to identify particular voices. They’re what enables you to separate and amplify particular voices in loud situations.
- Heschl’s gyrus (HG): This is the part of the auditory cortex that takes care of the first phase of the sorting process. Heschl’s gyrus or HG breaks down each individual voice and separates them into discrete 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 distinctions. Which voices can be comfortably moved to the background and which ones you want to focused on is figured out by the STG..
When you start to suffer from hearing damage, it’s harder for your brain to distinguish voices because your ears are lacking certain wavelengths of sound (high or low, depending on your hearing loss). Your brain can’t assign separate identities to each voice because it doesn’t have enough information. Consequently, it all blends together (which means discussions will harder to follow).
New Science = New Algorithm
It’s common for hearing aids to come with functions that make it less difficult 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 greater concept of what the process looks like. As an example, hearing aids that do more to differentiate voices can assist the Heschl’s gyrus a little, bringing about a better ability for you to comprehend what your coworkers are talking about in that loud restaurant.
The more we discover about how the brain works, specifically in connection with the ears, the better new technology will be capable of mimicking what happens in nature. And better hearing outcomes will be the result. Then you can concentrate a little more on enjoying yourself and a little less on straining to hear.