Sometimes when a person has a hard 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 bit about cleaning your room.
But it turns out that selective hearing is quite the ability, an impressive linguistic feat carried out by teamwork between your ears and brain.
The Stress Of Trying to Hear in a Crowd
This situation potentially feels familiar: you’re feeling tired from a long workday but your friends all really would like to go out for dinner and drinks. They pick the loudest restaurant (because it’s popular and the deep-fried cauliflower is delicious). And you spend the entire evening straining your ears, working hard to follow the conversation.
But it’s tough, and it’s taxing. This suggests that you could have hearing loss.
You think, maybe the restaurant was simply too loud. But… everyone else seemed to be having a great time. It seemed like you were the only one experiencing difficulty. Which gets you thinking: Why do ears that have hearing impairment have such a hard time with the noise of a crowded room? Why is it that being able to hear in a crowd is so quick to go? The answer, as reported by scientists, is selective hearing.
How Does Selective Hearing Operate?
The term “selective hearing” is a task that doesn’t even happen in the ears and is scientifically known as “hierarchical encoding”. This process almost exclusively happens in your brain. At least, that’s in line with a new study performed by a team from Columbia University.
Scientists have known for quite a while that human ears effectively work like a funnel: they collect all the signals and then deliver the raw information to your brain. That’s where the heavy lifting takes place, particularly the auditory cortex. Vibrations caused by moving air are translated by this portion of the brain into perceptible sound information.
Because of extensive research with CT and MRI scans, scientists have understood for years that the auditory cortex plays a considerable role in hearing, but they were stumped with regards to what those processes really look like. Scientists were able, by utilizing novel research techniques on individuals with epilepsy, to get a better picture of how the auditory cortex picks out voices in a crowd.
The Hierarchy of Hearing
And the information they found out are as follows: there are two components of the auditory cortex that perform most of the work in allowing you to identify individual voices. They’re what enables you to separate and amplify specific voices in loud situations.
- Superior temporal gyrus (STG): At some point your brain needs to make some value based choices and this is done in the STG once it receives the voices that were previously separated by the HG. 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): This is the region of the auditory cortex that takes care of the first phase of the sorting process. Heschl’s gyrus or HG processes each unique voice and separates them into distinct identities.
When you have hearing loss, your ears are lacking certain wavelengths so it’s harder for your brain to differentiate voices (depending on your hearing loss it could be high or low frequencies). Your brain isn’t given enough data to assign separate identities to each voice. Consequently, it all blends together (which makes interactions hard to follow).
A New Algorithm From New Science
It’s standard for hearing aids to have features that make it easier to hear in a crowd. But now that we understand what the basic process looks like, hearing aid manufacturers can integrate more of those natural functions into their instrument algorithms. For example, hearing aids that do more to identify voices can assist the Heschl’s gyrus a little, leading to a better capacity for you to understand what your coworkers are saying in that noisy restaurant.
The more we find out about how the brain works, particularly in combination with the ears, the better new technology will be capable of mimicking what takes place in nature. And that can lead to better hearing outcomes. Then you can focus a little more on enjoying yourself and a little less on straining to hear.