Selective hearing is a term that commonly is used as a pejorative, an insult. Maybe you heard your mother accuse your father of having “selective hearing” when she believed he might be ignoring her.
But it turns out that selective hearing is quite the skill, an amazing linguistic feat executed by teamwork between your ears and brain.
Hearing in a Crowd
This situation potentially seems familiar: you’ve been through a long day at work, but your buddies all insist on meeting up for dinner. They decide on the loudest restaurant (because it’s popular and the deep-fried cauliflower is delicious). And you spend the entire evening straining your ears, trying to follow the conversation.
But it’s very difficult and exhausting. This indicates that you may have hearing loss.
Maybe, you rationalize, the restaurant was simply too noisy. But… everyone else seemed to be having a great time. The only person who appeared to be having trouble was you. So you start to wonder: what is it about the packed room, the cacophony of voices all battling to be heard, that throws hearing-impaired ears for a loop? Why is it that being able to hear in a crowd is so quick to go? The answer, as reported by scientists, is selective hearing.
Selective Hearing – How Does it Work?
The scientific term for what we’re loosely calling selective hearing is “hierarchical encoding,” and it doesn’t take place inside of your ears at all. This process almost exclusively happens in your brain. At least, that’s in line with a new study performed by a team at Columbia University.
Ears work just like a funnel as scientists have known for quite a while: they collect all the impulses and then send the raw data to your brain. In the auditory cortex the real work is then done. Vibrations caused by moving air are interpreted by this part of the brain into recognizable sound information.
Because of comprehensive research with CT and MRI scans, scientists have known for years that the auditory cortex plays a crucial role in hearing, but they were clueless with regards to what those processes really look like. Scientists were able, by using unique research techniques on individuals with epilepsy, to get a better picture of how the auditory cortex discerns voices in a crowd.
The Hierarchy of Hearing
And here is what these intrepid scientists found out: there are two components of the auditory cortex that do most of the work in allowing you to identify distinct voices. And in noisy environments, they enable you to isolate and enhance particular voices.
- 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 individual voice and separates them into discrete identities.
- Superior temporal gyrus (STG): The separated voices move from the HG to the STG, and it’s at this point that your brain starts to make some value distinctions. Which voices can be safely moved to the background and which ones you want to pay attention to is figured out by the STG..
When you begin to suffer from hearing impairment, it’s more difficult for your brain to distinguish voices because your ears are lacking particular wavelengths of sound (depending on your hearing loss it could be high or low frequencies). Your brain can’t assign separate identities to each voice because it doesn’t have enough data. It all blurs together as a consequence (which makes conversations hard to follow).
A New Algorithm From New Science
It’s standard for hearing aids to come with features that make it easier to hear in a crowded situation. But hearing aid makers can now incorporate more of those natural functions into their algorithms because they have a better idea of what the process looks like. For instance, you will have a greater ability to hear and comprehend what your coworkers are talking about with hearing aids that assist the Heshl’s gyrus and do a little more to differentiate voices.
Technology will get better at mimicking what happens 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 concentrate a little less on struggling to hear and a little more on enjoying yourself.