Selective hearing is a term that commonly 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 going to the fair and (maybe intentionally) disregarded the bit about doing your chores.
But in reality it takes an amazing act of cooperation between your brain and your ears to have selective hearing.
The Difficulty Of Trying to Hear in a Crowd
Maybe you’ve experienced this scenario before: you’ve had a long day at work, but your friends all insist on meeting up for dinner. They choose the noisiest restaurant (because it’s trendy and the food is the best in town). 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, maybe the restaurant was just too noisy. But no one else appeared to be having difficulties. The only person who appeared to be having difficulty was you. So you start to wonder: Why do ears that have hearing impairment have such a hard time with the noise of a packed room? It seems like hearing well in a crowd is the first thing to go, but why? The answer, according to scientists, is selective hearing.
How Does Selective Hearing Operate?
The scientific term 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 nearly exclusively occurs in your brain. At least, that’s as reported by a new study carried out by a team from Columbia University.
Ears work just like a funnel which scientists have understood for quite a while: they collect all the signals and then send the raw data to your brain. That’s where the heavy lifting takes place, specifically the auditory cortex. Vibrations triggered by moving air are interpreted by this portion of the brain into recognizable sound information.
Because of considerable research with CT and MRI scans, scientists have recognized for years that the auditory cortex plays a crucial role in hearing, but they were stumped with regards to what those processes actually look like. Thanks to some innovative research methods concerning participants with epilepsy, scientists at Columbia were able to discover more about how the auditory cortex works when it comes to picking out voices in a crowd.
The Hierarchy of Hearing
And here is what these intrepid scientists learned: the majority of the work done by the auditory cortex to isolate specific voices is accomplished by two different parts. And in noisy conditions, they allow you to isolate and intensify specific voices.
- Superior temporal gyrus (STG): The separated voices go 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 focus on and which can be securely moved to the background.
- Heschl’s gyrus (HG): The first sorting phase is taken care of by this part of the auditory cortex. Heschl’s gyrus or HG breaks down each unique voice and separates them into discrete identities.
When you begin to suffer from hearing damage, it’s harder for your brain to differentiate voices because your ears are lacking particular wavelengths of sound (depending on your hearing loss it could be high or low frequencies). Your brain isn’t provided with enough information to assign individual identities to each voice. It all blurs together as a result (which makes conversations tough to follow).
New Science = New Algorithm
It’s common for hearing aids to have features that make it less difficult to hear in a crowded situation. But now that we know what the fundamental process looks like, hearing aid manufacturers can integrate more of those natural functions into their device algorithms. As an example, you will have a greater ability to hear and comprehend what your coworkers are saying with hearing aids that help the Heshl’s gyrus and do a little more to separate 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 improved hearing success. Then you can focus a little more on enjoying yourself and a little less on straining to hear.