Sometimes when an individual has a difficult time hearing, someone close to them insultingly says they have “selective hearing”. Perhaps 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 performed by teamwork between your ears and brain.
Hearing in a Crowd
Maybe you’ve dealt with this scenario before: you’ve been through a long day at work, but your friends all insist on meeting up for dinner. They choose the loudest restaurant (because it’s popular and the food is delicious). And you spend an hour and a half straining your ears, attempting to follow the conversation.
But it’s tough, and it’s taxing. And it’s an indication of hearing loss.
You think, maybe the restaurant was simply too loud. But no one else seemed to be struggling. It seemed like you were the only one having difficulty. So you begin to ask yourself: what is it about the crowded room, the cacophony of voices all struggling 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 what’s the reason? Scientists have started to discover the solution, and it all starts with selective hearing.
How Does Selective Hearing Operate?
The scientific name for what we’re loosely calling selective hearing is “hierarchical encoding,” and it doesn’t take place in your ears at all. This process nearly completely happens in your brain. At least, that’s in accordance with a new study performed by a team at Columbia University.
Ears work just like a funnel which scientists have understood for some time: they collect all the signals and then forward the raw information to your brain. In the auditory cortex the real work is then done. Vibrations triggered by moving air are translated by this part of the brain into perceptible sound information.
Because of extensive research with CT and MRI scans, scientists have recognized 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 unique research methods involving participants with epilepsy, scientists at Columbia were able to learn more about how the auditory cortex functions when it comes to discerning voices in a crowd.
The Hearing Hierarchy
And here is what these intrepid scientists found: there are two components of the auditory cortex that perform most of the work in helping you key in on individual voices. They’re what enables you to separate and amplify distinct voices in noisy situations.
- Superior temporal gyrus (STG): Sooner or later your brain will need to make some value based choices and this occurs in the STG after it receives the voices which were previously differentiated by the HG. The superior temporal gyrus determines which voices you want to pay attention to and which can be confidently moved to the background.
- Heschl’s gyrus (HG): This is the part of the auditory cortex that manages the first stage of the sorting process. Heschl’s gyrus or HG processes each unique voice and separates them into discrete identities.
When you have hearing impairment, your ears are lacking specific wavelengths so it’s harder for your brain to recognize voices (high or low, depending on your hearing loss). Your brain can’t assign individual identities to each voice because it doesn’t have enough data. As a result, it all blurs together (which means discussions will more difficult to understand).
New Science = New Algorithm
Hearing aids currently have features that make it easier to hear in loud circumstances. But hearing aid manufacturers can now include 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 capacity 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.
The more we discover about how the brain works, particularly in conjunction with the ears, the better new technology will be capable of mimicking what takes place in nature. And that can lead to better hearing outcomes. Then you can concentrate a little more on enjoying yourself and a little less on straining to hear.