Selective hearing is a phrase that commonly gets tossed about as a pejorative, an insult. Maybe you heard your mother suggest that your father had “selective hearing” when she thought he was ignoring her.
But in reality it takes an incredible act of teamwork between your brain and your ears to have selective hearing.
The Difficulty Of Trying to Hear in a Crowd
Perhaps you’ve experienced this situation before: you’ve been through a long day at work, but your friends all insist on meeting up for dinner. They pick the loudest restaurant (because it’s popular and the deep-fried cauliflower is the best in town). And you spend the entire evening straining your ears, attempting to follow the conversation.
But it’s challenging, and it’s taxing. This suggests that you might have hearing loss.
You think, perhaps the restaurant was just too noisy. But… everyone else appeared to be having a fine go of it. The only one who appeared to be having difficulty was you. So you begin to wonder: Why do ears with hearing impairment have such a difficult 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 why? Scientists have begun to reveal the answer, and it all starts with 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 take place inside of your ears at all. The majority of this process happens in the brain. At least, that’s in line with a new study carried out by a team at Columbia University.
Scientists have known for some time that human ears effectively work as a funnel: they gather all the impulses and then deliver the raw data to your brain. That’s where the real work happens, particularly the auditory cortex. Vibrations triggered by moving air are interpreted 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 substantial role in hearing, but they were stumped when it came to what those processes actually look like. Scientists were able, by using unique research techniques on individuals with epilepsy, to get a better understanding of how the auditory cortex discerns voices in a crowd.
The Hierarchy of Hearing
And here’s what these intrepid scientists found: there are two parts of the auditory cortex that accomplish most of the work in allowing you to key in on individual voices. They’re what allows you to separate and enhance specific voices in loud situations.
- Superior temporal gyrus (STG): Sooner or later your brain will need to make some value based decisions and this occurs in the STG once it receives the voices which were previously separated by the HG. Which voices can be safely moved to the background and which ones you want to focused on is determined by the STG..
- 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 breaks down each unique voice and separates them into distinguishable identities.
When you have hearing problems, your ears are missing particular wavelengths so it’s harder for your brain to differentiate voices (depending on your hearing loss it might be low or high frequencies). Your brain can’t assign individual identities to each voice because it doesn’t have enough information. Consequently, it all blurs together (meaning conversations will more difficult to follow).
A New Algorithm From New Science
It’s typical for hearing aids to have features that make it less difficult to hear in a crowded situation. But now that we understand what the basic process looks like, hearing aid companies can incorporate more of those natural operations into their device algorithms. For instance, hearing aids that do more to differentiate voices can help out the Heschl’s gyrus a little, leading to a better 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 functions in conjunction with the ears. 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.