Sometimes when an individual has a hard time hearing, somebody close to them insultingly suggests they have “selective hearing”. Perhaps you heard your mother suggest that your father had “selective hearing” when she believed he was ignoring her.
But actually selective hearing is quite the talent, an amazing linguistic task conducted by teamwork between your ears and brain.
Hearing in a Crowd
Maybe you’ve experienced this situation before: you’re feeling tired from a long workday but your friends all really want to go out for dinner and drinks. They choose the noisiest restaurant (because it’s trendy and the deep-fried cauliflower is delicious). And you strain and struggle to follow the conversation for over an hour and a half.
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. You seemed like the only one experiencing trouble. So you start to wonder: Why do ears with hearing impairment have such a hard time with the noise of a packed room? It seems as if hearing well in a crowded place is the first thing to go, but what’s the reason? Scientists have started to discover the solution, and it all starts with selective hearing.
How Does Selective Hearing Work?
The scientific name for what we’re broadly calling selective hearing is “hierarchical encoding,” and it doesn’t take place in your ears at all. The majority of this process occurs in the brain. At least, that’s in accordance with a new study performed by a team at Columbia University.
Scientists have recognized for quite a while that human ears effectively work as 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 interpreted by this part of the brain into recognizable sound information.
Because of extensive research with MRI and CT scans, scientists have understood for years that the auditory cortex plays a crucial role in hearing, but they were clueless regarding what those processes really look like. Scientists were able, by utilizing unique research techniques on people with epilepsy, to get a better picture of how the auditory cortex picks out voices in a crowd.
The Hierarchy of Hearing
And here is what these intrepid scientists found out: there are two regions of the auditory cortex that do most of the work in helping you key in on particular voices. They’re what enables you to separate and intensify particular voices in loud situations.
- Heschl’s gyrus (HG): The first sorting phase is taken care of by this part of the auditory cortex. Heschl’s gyrus or HG breaks down each individual voice and separates them into distinct identities.
- Superior temporal gyrus (STG): The differentiated voices move from the HG to the STG, and it’s here that your brain starts to make some value distinctions. The superior temporal gyrus determines which voices you want to pay attention to and which can be safely moved to the background.
When you have hearing impairment, your ears are missing particular wavelengths so it’s harder for your brain to recognize voices (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 discussions tough to follow).
New Science = New Algorithm
Hearing aids already have functions that make it less difficult to hear in loud environments. But now that we know what the basic process looks like, hearing aid manufacturers can integrate more of those natural operations into their device algorithms. As an example, hearing aids that do more to distinguish voices can assist the Heschl’s gyrus a little, leading to a better ability for you to comprehend what your coworkers are saying in that loud restaurant.
Technology will get better at mimicking what occurs in nature as we learn more about how the brain functions in conjunction with the ears. And better hearing success will be the outcome. That way, you can concentrate a little less on straining to hear and a little more on enjoying yourself.