Selective hearing is a term that normally is used as a pejorative, an insult. Maybe you heard your mother suggest that your father had “selective hearing” when she believed he might be ignoring her.
But actually selective hearing is quite the skill, an impressive linguistic task executed by cooperation between your ears and brain.
Hearing in a Crowd
This situation potentially feels familiar: you’re feeling tired from a long workday but your friends all really want to go out for dinner and drinks. They pick the noisiest restaurant (because it’s popular and the food is delicious). And you spend an hour and a half straining your ears, working hard to follow the conversation.
But it’s challenging, and it’s taxing. And it’s a sign of hearing loss.
You think, maybe the restaurant was simply too noisy. But… everyone else appeared to be having a fine go of it. The only person who appeared to be having difficulty was you. So you begin to wonder: Why do ears that have hearing impairment have such a hard time with the noise of a crowded room? Why is it that being able to hear in a crowd is so quick to go? Scientists have begun to discover the solution, and it all begins with selective hearing.
Selective Hearing – How Does it Work?
The scientific term for what we’re broadly calling selective hearing is “hierarchical encoding,” and it doesn’t take place inside of your ears at all. This process nearly entirely occurs in your brain. At least, that’s according to a new study carried out by a team from Columbia University.
Scientists have recognized for some time that human ears basically work as a funnel: they deliver 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 part of the brain into recognizable sound information.
Just what these processes look like had remained a mystery despite the existing knowledge of the role played by the auditory cortex in the hearing process. Thanks to some innovative research techniques including participants with epilepsy, scientists at Columbia were able to learn more about how the auditory cortex functions in terms of picking out voices in a crowd.
The Hierarchy of Hearing
And here is what these intrepid scientists found out: the majority of the work done by the auditory cortex to isolate particular voices is accomplished by two separate parts. They’re what allows you to sort and intensify distinct voices in loud situations.
- Heschl’s gyrus (HG): The first sorting phase is handled by this region of the auditory cortex. Heschl’s gyrus or HG breaks down each individual voice and separates them into discrete identities.
- Superior temporal gyrus (STG): At some point your brain will need to make some value based choices and this occurs in the STG once it receives the voices which were previously differentiated by the HG. The superior temporal gyrus determines which voices you want to give attention to and which can be confidently moved to the background.
When you start to suffer with hearing problems, it’s harder for your brain to differentiate voices because your ears are missing particular wavelengths of sound (high or low, depending on your hearing loss). Your brain isn’t supplied with enough information to assign separate identities to each voice. It all blends together as a consequence (which means conversations will more difficult to follow).
A New Algorithm From New Science
Hearing aids already have features that make it less difficult to hear in loud circumstances. But hearing aid makers can now incorporate more of those natural functions into their algorithms because they have a better concept of what the process looks like. For example, hearing aids that do more to distinguish voices can assist the Heschl’s gyrus a little bit, bringing about a greater ability for you to understand what your coworkers are saying in that noisy restaurant.
The more we learn about how the brain works, specifically in connection with the ears, the better new technology will be able to mimic what happens in nature. And that can lead to improved hearing outcomes. Then you can concentrate a little more on enjoying yourself and a little less on straining to hear.
