Selective hearing is a term that usually gets tossed about as a pejorative, an insult. When your mother used to accuse you of having “selective hearing,” she meant that you listened to the part about chocolate cake for dessert and (perhaps deliberately) ignored the part about doing your chores.
But actually it takes an amazing act of teamwork between your ears and your brain to have selective hearing.
Hearing in a Crowd
This scenario probably feels familiar: you’ve had a long day at work, but your buddies all insist on meeting up for dinner. And of course, they want to go to the noisiest restaurant (because they have incredible food and live entertainment). And you strain and struggle to follow the conversation for over an hour and a half.
But it’s difficult, and it’s taxing. This suggests that you might have hearing loss.
Maybe, you rationalize, the restaurant was simply too loud. But no one else seemed to be having difficulties. The only one who appeared to be having trouble was you. Which makes you think: what is it about the packed room, the cacophony of voices all struggling to be heard, that causes hearing impaired ears to struggle? It seems as if hearing well in a crowded place is the first thing to go, but why? The answer, according to scientists, is selective hearing.
Selective Hearing – How Does it Work?
The term “selective hearing” is a task that doesn’t even occur in the ears and is scientifically called “hierarchical encoding”. The majority of this process occurs in the brain. At least, that’s in line with a new study carried out by a team from Columbia University.
Ears work just like a funnel as scientists have recognized for quite a while: they compile all the signals and then forward the raw information to your brain. In the auditory cortex the real work is then done. That’s the part of your brain that processes all those signals, interpreting impressions of moving air into recognizable sounds.
Because of extensive research with MRI and CT scans, scientists have known 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 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 is what these intrepid scientists found out: there are two regions of the auditory cortex that perform most of the work in allowing you to identify particular voices. And in noisy settings, they enable you to separate and enhance particular voices.
- Superior temporal gyrus (STG): The differentiated voices go from the HG to the STG, and it’s here that your brain starts to make some value distinctions. Which voices can be safely moved to the background and which ones you want to focused on is determined by the STG..
- Heschl’s gyrus (HG): The first sorting stage is managed by this part of the auditory cortex. Researchers found that the Heschl’s gyrus (we’re just going to call it HG from now on) was processing each unique voice, classifying them via unique identities.
When you have hearing loss, your ears are lacking specific wavelengths so it’s more difficult for your brain to distinguish voices (depending on your hearing loss it could be low or high frequencies). Your brain isn’t provided with enough data to assign separate identities to each voice. As a result, it all blurs together (which makes conversations difficult to follow).
A New Algorithm From New Science
Hearing aids currently have functions that make it less difficult to hear in loud settings. But now that we understand what the basic process looks like, hearing aid makers can incorporate more of those natural operations into their device algorithms. For instance, hearing aids that do more to identify voices can help out the Heschl’s gyrus a little, bringing about a better ability for you to comprehend what your coworkers are saying in that noisy restaurant.
The more we discover about how the brain works, particularly in connection with the ears, the better new technology will be capable of mimicking what happens in nature. And better hearing success will be the outcome. Then you can focus a little more on enjoying yourself and a little less on straining to hear.