Sometimes when an individual has a difficult time hearing, somebody close to them insultingly says they have “selective hearing”. Maybe you heard your mother suggest that your father had “selective hearing” when she thought he was ignoring her.
But actually selective hearing is quite the skill, an impressive linguistic feat performed by cooperation between your brain and ears.
Hearing in a Crowd
This scenario potentially seems familiar: you’ve been through a long day at work, but your buddies all insist on going out to dinner. They decide on the noisiest restaurant (because they have incredible food and live entertainment). And you strain and struggle to follow the conversation for the entire evening.
But it’s difficult, and it’s taxing. This suggests that you could have hearing loss.
Maybe, you rationalize, the restaurant was simply too loud. But… everyone else appeared to be having a fine go of it. The only person who appeared to be having difficulty was you. So you begin to wonder: what is it about the packed room, the cacophony of voices all trying 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 why? The solution, as reported by scientists, is selective hearing.
How Does Selective Hearing Operate?
The scientific term for what we’re broadly calling selective hearing is “hierarchical encoding,” and it doesn’t take place in your ears at all. This process nearly entirely happens in your brain. At least, that’s in line with a new study performed by a team from Columbia University.
Ears work just like a funnel as scientists have recognized for some time: they send all of the unprocessed data that they gather to your brain. In the auditory cortex the real work is then done. That’s the part of your gray matter that processes all those signals, translating sensations of moving air into perceptible sounds.
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 clueless regarding what those processes really look like. Scientists were able, by utilizing novel research techniques on people with epilepsy, to get a better picture of how the auditory cortex discerns voices in a crowd.
The Hierarchy of Hearing
And the facts they discovered follows: most of the work done by the auditory cortex to isolate specific voices is performed by two separate regions. They’re what enables you to sort and amplify distinct voices in noisy environments.
- Superior temporal gyrus (STG): The separated voices move from the HG to the STG, and it’s here that your brain starts to make some value determinations. The superior temporal gyrus figures out which voices you want to pay attention to and which can be securely moved to the background.
- Heschl’s gyrus (HG): The first sorting stage is managed by this part of the auditory cortex. Heschl’s gyrus or HG processes each unique voice and separates them into discrete identities.
When you start to suffer with hearing problems, it’s more difficult for your brain to differentiate voices because your ears are missing particular wavelengths of sound (depending on your hearing loss it might be high or low frequencies). Your brain isn’t given enough data to assign individual identities to each voice. As a result, it all blurs together (which makes discussions difficult to follow).
A New Algorithm From New Science
It’s standard for hearing aids to come with functions that make it easier to hear in a crowded situation. But hearing aid manufacturers can now integrate more of those natural functions into their algorithms because they have a better concept of what the process looks like. As an example, you will have a greater ability to hear and understand what your coworkers are saying with hearing aids that assist 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 works in combination with the ears. And that can result in improved hearing outcomes. That way, you can focus a little less on struggling to hear and a little more on enjoying yourself.