Selective hearing is a phrase that normally is used 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 (maybe intentionally) disregarded the part about doing your chores.
But actually it takes an incredible act of cooperation between your brain and your ears to have selective hearing.
Hearing in a Crowd
Perhaps you’ve experienced this scenario 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 popular 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 tough, and it’s taxing. This indicates that you might have hearing loss.
You think, maybe the restaurant was simply too loud. But… everyone else appeared to be having a great time. The only one who appeared to be having trouble was you. Which makes you think: what is it about the crowded room, the cacophony of voices all battling to be heard, that causes hearing impaired ears to struggle? It seems like hearing well in a crowd is the first thing to go, but what’s the reason? The solution, according to scientists, is selective hearing.
Selective Hearing – How Does it Work?
The term “selective hearing” is a process that doesn’t even occur in the ears and is scientifically called “hierarchical encoding”. This process nearly completely occurs in your brain. At least, that’s as reported by a new study carried out by a team from Columbia University.
Scientists have known for some time that human ears effectively work like a funnel: they deliver all of the unprocessed data that they collect to your brain. In the auditory cortex the real work is then accomplished. Vibrations caused by moving air are translated by this part of the brain into perceptible sound information.
Because of extensive research with MRI and CT scans, scientists have understood for years that the auditory cortex plays a considerable role in hearing, but they were stumped with regards to what those processes really look like. Thanks to some novel research methods concerning participants with epilepsy, scientists at Columbia were able to find out more about how the auditory cortex functions in terms of picking out voices in a crowd.
The Hierarchy of Hearing
And here is what these intrepid scientists found: there are two parts of the auditory cortex that accomplish most of the work in allowing you to identify individual voices. They’re what enables you to separate and enhance distinct voices in noisy environments.
- 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. The superior temporal gyrus determines which voices you want to focus on and which can be securely moved to the background.
- Heschl’s gyrus (HG): This is the part of the auditory cortex that takes care of the first stage of the sorting process. Scientists discovered that the Heschl’s gyrus (we’re just going to call it HG from now on) was breaking down each distinct voice, separating them into unique identities.
When you have hearing impairment, your ears are missing certain wavelengths so it’s harder for your brain to differentiate voices (low or high, depending on your hearing loss). Your brain can’t assign separate identities to each voice because it doesn’t have enough information. As a result, it all blurs together (which makes interactions difficult to follow).
New Science = New Algorithm
It’s standard for hearing aids to come with features that make it less difficult to hear in a crowd. But now that we understand what the basic process looks like, hearing aid makers can integrate more of those natural functions into their instrument algorithms. As an example, you will have a better 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 identify voices.
Technology will get better at mimicking what occurs in nature as we uncover more about how the brain works in combination with the ears. And better hearing outcomes will be the outcome. Then you can focus a little more on enjoying yourself and a little less on straining to hear.