Sometimes when an individual has a difficult time hearing, someone close to them insultingly suggests they have “selective hearing”. Maybe you heard your mother suggest that your father had “selective hearing” when she thought he might be ignoring her.
But actually it takes an amazing act of cooperation between your ears and your brain to have selective hearing.
The Difficulty Of Trying to Hear in a Crowd
Perhaps you’ve experienced this scenario before: you’ve had a long day at work, but your friends all insist on going out to dinner. They decide on the loudest restaurant (because they have incredible food and live entertainment). And you spend an hour and a half straining your ears, trying to follow the conversation.
But it’s very difficult and exhausting. This indicates that you may have hearing loss.
You think, perhaps the restaurant was just too noisy. But no one else seemed to be having difficulties. It seemed like you were the only one having difficulty. Which gets you thinking: Why do ears that have hearing impairment have such a difficult time with the noise of a crowded room? Why is it that being able to hear in a crowd is so challenging? Scientists have begun to discover the solution, and it all begins with selective hearing.
How Does Selective Hearing Work?
The phrase “selective hearing” is a process that doesn’t even take place in the ears and is scientifically called “hierarchical encoding”. This process almost entirely happens in your brain. At least, that’s according to a new study performed by a team at Columbia University.
Ears work like a funnel which scientists have recognized for some time: they send all of the raw data that they gather to your brain. In the auditory cortex the real work is then accomplished. Vibrations triggered by moving air are interpreted by this portion of the brain into perceptible sound information.
Just what these processes look like had remained a mystery in spite of the established understanding of the role played by the auditory cortex in the hearing process. Scientists were able, by making use of unique research techniques on people with epilepsy, to get a better understanding of how the auditory cortex discerns voices in a crowd.
The Hearing Hierarchy
And here is what these intrepid scientists learned: most of the work accomplished by the auditory cortex to isolate particular voices is performed by two different parts. And in loud conditions, they enable you to separate and enhance certain voices.
- 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 unique voice and separates them into distinguishable identities.
- Superior temporal gyrus (STG): At some point your brain will need to make some value based choices and this is done in the STG after it receives the voices that were previously separated 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.
When you start to suffer with hearing damage, it’s more difficult for your brain to identify voices because your ears are lacking particular wavelengths of sound (high or low, based upon your hearing loss). Your brain can’t assign separate identities to each voice because it doesn’t have enough data. As a result, it all blurs together (which means conversations will more difficult to follow).
A New Algorithm From New Science
It’s typical for hearing aids to have features that make it easier to hear in a crowd. But hearing aid manufacturers can now incorporate more of those natural functions into their algorithms because they have a better concept of what the process looks like. For instance, hearing aids that do more to differentiate voices can help out the Heschl’s gyrus a little bit, leading to a greater ability for you to understand what your coworkers are saying in that loud restaurant.
Technology will get better at mimicking what takes place in nature as we uncover more about how the brain really 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.