Sometimes when a person has a hard time hearing, someone close to them insultingly suggests they have “selective hearing”. Maybe you heard your mother accuse your father of having “selective hearing” when she believed he was ignoring her.
But it turns out that selective hearing is quite the talent, an impressive linguistic feat executed by cooperation between your ears and brain.
The Difficulty Of Trying to Hear in a Crowd
This scenario potentially seems familiar: you’re feeling burnt out 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 trendy and the deep-fried cauliflower is the best in town). And you spend an hour and a half straining your ears, attempting to follow the conversation.
But it’s challenging, 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 appeared to be struggling. The only person who appeared to be having trouble was you. Which makes you think: what is it about the crowded room, the cacophony of voices all trying to be heard, that causes hearing impaired ears to struggle? It seems like hearing well in a crowded place is the first thing to go, but why? Scientists have begun to discover the answer, and it all begins with selective hearing.
How Does Selective Hearing Operate?
The phrase “selective hearing” is a process that doesn’t even happen in the ears and is technically known as “hierarchical encoding”. Most of this process occurs in the brain. At least, that’s according to a new study performed by a team at Columbia University.
Ears work like a funnel which scientists have recognized for some time: they forward all of the raw data that they gather to your brain. In the auditory cortex the real work is then accomplished. That’s the part of your gray matter that handles all those signals, translating sensations of moving air into perceptible sounds.
Because of significant research with CT and MRI scans, scientists have understood for years that the auditory cortex plays a substantial 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 here’s what these intrepid scientists found: the majority of the work performed by the auditory cortex to isolate distinct voices is accomplished by two separate parts. And in noisy environments, they allow you to isolate and amplify particular voices.
- Heschl’s gyrus (HG): This is the region of the auditory cortex that manages the first stage of the sorting process. Heschl’s gyrus or HG processes each unique voice and separates them into discrete identities.
- Superior temporal gyrus (STG): At some point your brain will need to make some value based decisions and this happens in the STG once it receives the voices which were previously separated by the HG. The superior temporal gyrus determines which voices you want to give attention to and which can be safely moved to the background.
When you have hearing impairment, your ears are missing particular wavelengths so it’s harder for your brain to recognize voices (low or high, based upon your hearing loss). Your brain can’t assign separate identities to each voice because it doesn’t have enough information. It all blurs together as a result (which makes interactions difficult 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 fundamental process looks like, hearing aid manufacturers can incorporate more of those natural functions into their instrument algorithms. For example, you will have a better ability to hear and understand what your coworkers are saying with hearing aids that help the Heshl’s gyrus and do a little more to separate voices.
Technology will get better at mimicking what occurs in nature as we discover more about how the brain really works in conjunction with the ears. And better hearing success will be the outcome. That way, you can focus a little less on struggling to hear and a little more on enjoying yourself.