Selective hearing is a phrase that usually is used as a pejorative, an insult. When your mother used to accuse you of having “selective hearing,” she meant that you paid attention to the part about chocolate cake for dessert and (perhaps intentionally) disregarded the part about cleaning your room.
But actually selective hearing is quite the talent, an amazing linguistic accomplishment performed by cooperation between your ears and brain.
The Difficulty Of Trying to Hear in a Crowd
Maybe you’ve dealt with this scenario before: you’re feeling tired from a long workday but your friends all really want to go out for dinner and drinks. And of course, they want to go to the loudest restaurant (because it’s trendy and the food is delicious). And you spend an hour and a half straining your ears, trying to follow the conversation.
But it’s very difficult and exhausting. And it’s an indication of hearing loss.
Perhaps, you rationalize, the restaurant was simply too noisy. But… everyone else seemed to be having a great time. It seemed like you were the only one experiencing difficulty. So you begin to wonder: Why do ears that have hearing impairment have such a difficult time with the noise of a crowded room? Just why is it that being able to hear in a crowd is so quick to go? Scientists have begun to reveal the answer, and it all starts with selective hearing.
How Does Selective Hearing Function?
The scientific term for what we’re loosely calling selective hearing is “hierarchical encoding,” and it doesn’t take place inside of your ears at all. Most of this process occurs in the 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 effectively work as a funnel: they compile all the impulses and then deliver the raw data 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 in spite of the existing understanding of the role played by the auditory cortex in the process of hearing. Scientists were able, by utilizing novel 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 the information they found are as follows: most of the work performed by the auditory cortex to isolate distinct voices is performed by two different regions. And in noisy conditions, they allow you to isolate and intensify particular voices.
- Heschl’s gyrus (HG): This is the part of the auditory cortex that manages the first stage of the sorting process. Researchers discovered that the Heschl’s gyrus (we’re simply going to call it HG from now on) was breaking down each individual voice, separating them into unique identities.
- Superior temporal gyrus (STG): Sooner or later your brain needs to make some value based choices and this occurs in the STG after it receives the voices that were previously differentiated by the HG. The superior temporal gyrus figures out which voices you want to give attention to and which can be safely moved to the background.
When you start to suffer from hearing damage, it’s more difficult 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 furnished with enough data to assign separate identities to each voice. It all blends together as a consequence (meaning interactions will more difficult to follow).
New Science = New Algorithm
Hearing aids currently have features that make it easier to hear in loud settings. But now that we understand what the basic process looks like, hearing aid makers can incorporate more of those natural functions into their instrument algorithms. For instance, you will have a better ability to hear and understand what your coworkers are talking about with hearing aids that assist the Heshl’s gyrus and do a little more to differentiate voices.
Technology will get better at mimicking what happens in nature as we learn more about how the brain works in combination with the ears. And better hearing success will be the result. That way, you can concentrate a little less on straining to hear and a little more on enjoying yourself.