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 cleaning your room.
But actually selective hearing is quite the ability, an amazing linguistic task carried out by teamwork between your brain and ears.
Hearing in a Crowd
Perhaps you’ve experienced this situation before: you’ve had a long day at work, but your buddies all insist on going out to dinner. They pick the loudest restaurant (because they have amazing food and live entertainment). And you spend an hour and a half straining your ears, working hard to follow the conversation.
But it’s difficult, and it’s taxing. This indicates that you might have hearing loss.
You think, perhaps the restaurant was simply too noisy. But no one else seemed to be struggling. It seemed like you were the only one experiencing difficulty. So you begin to wonder: what is it about the packed room, the cacophony of voices all struggling to be heard, that throws hearing-impaired ears for a loop? It seems as if hearing well in a crowded place is the first thing to go, but what’s the reason? The answer, as reported by scientists, is selective hearing.
How Does Selective Hearing Work?
The scientific name for what we’re loosely calling selective hearing is “hierarchical encoding,” and it doesn’t happen inside of your ears at all. Most of this process happens in the brain. At least, that’s in line with a new study performed by a team from Columbia University.
Ears work like a funnel as scientists have known for some time: they gather all the impulses and then forward the raw information to your brain. In the auditory cortex the real work is then accomplished. That’s the part of your brain that processes all those impulses, translating sensations of moving air into identifiable sounds.
Precisely what these processes look like had remained a mystery in spite of the existing knowledge of the role played by the auditory cortex in the hearing process. Thanks to some innovative research methods including participants with epilepsy, scientists at Columbia were able to learn more about how the auditory cortex works in relation to discerning voices in a crowd.
The Hearing Hierarchy
And the facts they found out are as follows: there are two parts of the auditory cortex that perform most of the work in helping you identify distinct voices. They’re what enables you to separate and enhance specific voices in loud situations.
- Superior temporal gyrus (STG): The differentiated voices move 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 freely moved to the background and which ones you want to pay attention to is determined by the STG..
- Heschl’s gyrus (HG): The first sorting stage is taken care of by this region of the auditory cortex. Heschl’s gyrus or HG breaks down each unique voice and separates them into discrete identities.
When you have hearing problems, your ears are lacking specific wavelengths so it’s harder for your brain to recognize voices (low or high, based upon your hearing loss). Your brain isn’t supplied with enough information to assign individual identities to each voice. It all blurs together as a result (which means conversations will more difficult to follow).
New Science = New Algorithm
Hearing aids already have functions that make it less difficult to hear in loud settings. But hearing aid manufacturers can now incorporate more of those natural functions into their algorithms because they have a greater idea of what the process looks like. As an example, you will have a better capacity to hear and comprehend what your coworkers are saying with hearing aids that assist the Heshl’s gyrus and do a little more to separate voices.
The more we find out about how the brain works, especially 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. That way, you can focus a little less on straining to hear and a little more on enjoying yourself.