Sometimes when an individual has a difficult time hearing, somebody close to them insultingly says they have “selective hearing”. Maybe you heard your mother suggest that your father had “selective hearing” when she believed he might be ignoring her.
But in reality it takes an amazing act of cooperation between your brain and your ears to have selective hearing.
Hearing in a Crowd
Perhaps you’ve dealt with this situation before: you’re feeling tired from a long day at work but your friends all really would like to go out for dinner and drinks. They choose the noisiest restaurant (because it’s popular and the food is delicious). And you spend the entire evening straining your ears, working hard to follow the conversation.
But it’s very difficult and exhausting. And it’s an indication of hearing loss.
You think, perhaps the restaurant was simply too noisy. But… everyone else appeared to be having a great time. The only person who appeared to be having difficulty was you. So you begin to wonder: what is it about the packed room, the cacophony of voices all struggling to be heard, that causes hearing impaired ears to struggle? It seems as if hearing well in a crowded place is the first thing to go, but what’s the reason? Scientists have begun to discover the answer, and it all begins with selective hearing.
How Does Selective Hearing Function?
The scientific name for what we’re loosely calling selective hearing is “hierarchical encoding,” and it doesn’t take place inside of 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.
Ears work like a funnel which scientists have understood for quite a while: they gather all the impulses and then deliver the raw information to your brain. That’s where the real work occurs, particularly the auditory cortex. Vibrations caused by moving air are translated by this part of the brain into perceptible sound information.
Because of comprehensive research with MRI and CT scans, scientists have recognized for years that the auditory cortex plays a considerable role in hearing, but they were clueless when it came to what those processes really look like. Scientists were able, by making use of unique research techniques on people with epilepsy, to get a better picture of how the auditory cortex picks out voices in a crowd.
The Hearing Hierarchy
And here is what these intrepid scientists found out: the majority of the work done by the auditory cortex to isolate distinct voices is done by two separate regions. They’re what enables you to separate and intensify distinct voices in noisy environments.
- Superior temporal gyrus (STG): The separated voices move from the HG to the STG, and it’s here that your brain begins to make some value determinations. The superior temporal gyrus figures out which voices you want to focus on and which can be securely moved to the background.
- Heschl’s gyrus (HG): This is the region of the auditory cortex that deals with the first stage of the sorting process. Heschl’s gyrus or HG processes each individual voice and separates them into distinguishable identities.
When you start to suffer from hearing damage, it’s more difficult for your brain to identify voices because your ears are lacking particular wavelengths of sound (low or high, based upon your hearing loss). Your brain isn’t supplied with enough data to assign individual identities to each voice. As a result, it all blends together (which makes interactions difficult to follow).
A New Algorithm From New Science
It’s standard for hearing aids to have features that make it easier to hear in a crowded situation. But now that we know what the fundamental process looks like, hearing aid manufacturers can integrate more of those natural functions into their instrument algorithms. For example, hearing aids that do more to distinguish voices can assist the Heschl’s gyrus a little bit, resulting in a greater ability for you to comprehend what your coworkers are talking about in that loud restaurant.
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 success will be the outcome. That way, you can focus a little less on straining to hear and a little more on enjoying yourself.