Selective hearing is a phrase that normally gets tossed about as a pejorative, an insult. Perhaps you heard your mother accuse your father of having “selective hearing” when she believed he was ignoring her.
But it turns out that selective hearing is quite the talent, an amazing linguistic task executed by cooperation between your brain and ears.
The Difficulty Of Trying to Hear in a Crowd
Perhaps you’ve experienced this scenario before: you’ve been through a long day at work, but your buddies all insist on going out to dinner. They pick the loudest restaurant (because it’s popular and the food is the best in town). 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 an indication of hearing loss.
You think, maybe the restaurant was just too loud. But… everyone else seemed to be having a great time. The only person who appeared to be having trouble 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? Just why is it that being able to hear in a crowd is so challenging? Scientists have started to reveal the solution, and it all starts with selective hearing.
How Does Selective Hearing Operate?
The scientific term for what we’re broadly calling selective hearing is “hierarchical encoding,” and it doesn’t happen in your ears at all. Most of this process happens in the brain. At least, that’s according to a new study done by a team at Columbia University.
Ears work just like a funnel as scientists have known for quite a while: they deliver all of the unprocessed data that they collect to your brain. In the auditory cortex the real work is then done. Vibrations triggered by moving air are interpreted by this part of the brain into perceptible sound information.
Exactly what these processes look like had remained a mystery despite the existing understanding of the role played by the auditory cortex in the hearing process. Scientists were able, by utilizing novel research techniques on individuals with epilepsy, to get a better picture of how the auditory cortex picks out voices in a crowd.
The Hearing Hierarchy
And the information they found are as follows: most of the work done by the auditory cortex to isolate specific voices is accomplished by two different parts. They’re what allows you to sort and intensify specific voices in noisy environments.
- Heschl’s gyrus (HG): The first sorting stage is managed by this region of the auditory cortex. Heschl’s gyrus or HG processes each individual voice and separates them into discrete identities.
- Superior temporal gyrus (STG): The differentiated voices go from the HG to the STG, and it’s here that your brain begins to make some value distinctions. Which voices can be safely moved to the background and which ones you want to pay attention to is determined by the STG..
When you start to suffer from hearing impairment, it’s more difficult for your brain to differentiate voices because your ears are missing particular wavelengths of sound (low or high, depending on your hearing loss). Your brain isn’t given enough information to assign individual identities to each voice. Consequently, it all blends together (which makes conversations hard to follow).
A New Algorithm From New Science
Hearing aids currently have features that make it easier to hear in loud environments. But hearing aid makers can now incorporate more of those natural functions into their algorithms because they have a greater concept of what the process looks like. For example, 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 differentiate voices.
The more we discover about how the brain works, specifically in connection with the ears, the better new technology will be capable of mimicking what happens in nature. And better hearing success will be the outcome. Then you can focus a little more on enjoying yourself and a little less on straining to hear.