Selective hearing is a phrase that commonly gets tossed about as a pejorative, an insult. Perhaps you heard your mother accuse your father of having “selective hearing” when she believed he might be ignoring her.
But in reality it takes an incredible act of cooperation between your brain and your ears to have selective hearing.
Hearing in a Crowd
This scenario probably seems familiar: you’re feeling tired from a long day at work but your friends all really want to go out for dinner and drinks. And of course, they want to go to the loudest restaurant (because it’s popular and the food is the best in town). And you strain and struggle to understand the conversation for over an hour and a half.
But it’s difficult, and it’s taxing. And it’s an indication of hearing loss.
You think, perhaps the restaurant was simply too loud. But… everyone else appeared to be having a great time. The only person who appeared to be having trouble was you. Which gets you thinking: what is it about the crowded room, the cacophony of voices all trying to be heard, that causes hearing impaired ears to struggle? Just why is it that being able to hear in a crowd is so quick to go? Scientists have begun to discover the solution, and it all starts with selective hearing.
How Does Selective Hearing Work?
The term “selective hearing” is a process that doesn’t even occur in the ears and is scientifically known as “hierarchical encoding”. Most of this process happens in the brain. At least, that’s in accordance with a new study carried out by a team at Columbia University.
Ears work like a funnel which scientists have understood for quite a while: they gather all the signals and then send the raw information to your brain. That’s where the heavy lifting occurs, specifically the auditory cortex. Vibrations triggered by moving air are translated by this portion of the brain into recognizable sound information.
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 actually look like. Scientists were able, by using unique research techniques on people with epilepsy, to get a better understanding of how the auditory cortex picks out voices in a crowd.
The Hierarchy of Hearing
And here is what these intrepid scientists discovered: there are two parts of the auditory cortex that manage most of the work in allowing you to key in on specific voices. They’re what allows you to separate and amplify distinct voices in loud environments.
- Superior temporal gyrus (STG): The differentiated voices go from the HG to the STG, and it’s at this point that your brain starts to make some value determinations. Which voices can be comfortably moved to the background and which ones you want to pay attention to is determined by the STG..
- Heschl’s gyrus (HG): This is the region of the auditory cortex that deals with the first stage of the sorting process. Scientists discovered that the Heschl’s gyrus (we’re just going to call it HG from now on) was processing each distinct voice, classifying them via individual identities.
When you have hearing problems, your ears are lacking particular wavelengths so it’s more difficult for your brain to recognize voices (depending on your hearing loss it might be high or low frequencies). Your brain isn’t furnished with enough information to assign separate identities to each voice. It all blurs together as a consequence (which makes discussions tough to follow).
New Science = New Algorithm
Hearing aids already have features that make it less difficult to hear in loud situations. 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. For instance, you will have a better 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 distinguish voices.
The more we discover about how the brain works, especially in combination with the ears, the better new technology will be capable of mimicking what happens in nature. 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.