Sometimes when an individual has a difficult time hearing, someone close to them insultingly suggests they have “selective hearing”. When your mother used to accuse you of having “selective hearing,” she meant that you paid attention to the part about going to the fair and (maybe deliberately) disregarded the bit about cleaning your room.
But actually selective hearing is quite the talent, an impressive linguistic accomplishment conducted by teamwork between your brain and ears.
Hearing in a Crowd
Maybe you’ve dealt with this situation before: you’re feeling tired from a long day at work but your friends all really want to go out for dinner and drinks. And naturally, they want to go to the noisiest restaurant (because it’s trendy and the deep-fried cauliflower is the best in town). And you strain and struggle to follow the conversation for over an hour and a half.
But it’s challenging, and it’s taxing. This suggests that you may have hearing loss.
Maybe, you rationalize, the restaurant was just too loud. But… everyone else appeared to be having a great time. You seemed like the only one experiencing trouble. So you begin to ask yourself: what is it about the crowded room, the cacophony of voices all trying to be heard, that causes hearing impaired ears to struggle? 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 name for what we’re broadly calling selective hearing is “hierarchical encoding,” and it doesn’t happen inside of your ears at all. This process nearly exclusively happens in your brain. At least, that’s in line with a new study carried out by a team at Columbia University.
Ears work like a funnel as scientists have understood for some time: they send all of the unprocessed data that they collect 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 recognizable sounds.
Just what these processes look like was still unknown in spite of the existing understanding of the role played by the auditory cortex in the hearing process. Scientists were able, by using novel 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 the information they found are as follows: most of the work performed by the auditory cortex to isolate particular voices is done by two different parts. And in loud conditions, they allow you to isolate and enhance certain voices.
- 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. 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): The first sorting phase is managed by this part of the auditory cortex. Heschl’s gyrus or HG breaks down each individual voice and separates them into discrete identities.
When you begin to suffer with hearing damage, it’s more difficult for your brain to identify voices because your ears are missing particular wavelengths of sound (low or high, depending on your hearing loss). Your brain isn’t supplied with enough information to assign individual identities to each voice. As a result, it all blurs together (meaning interactions will harder to follow).
A New Algorithm From New Science
It’s typical for hearing aids to come with features that make it less difficult to hear in a crowd. But hearing aid manufacturers 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 better capacity to hear and comprehend what your coworkers are talking about with hearing aids that help the Heshl’s gyrus and do a little more to differentiate voices.
The more we find out about how the brain works, specifically 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. Then you can focus a little more on enjoying yourself and a little less on straining to hear.