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 suspected he was ignoring her.
But actually selective hearing is quite the talent, an impressive linguistic accomplishment performed by teamwork between your ears and brain.
Hearing in a Crowd
Maybe you’ve encountered this scenario before: you’re feeling tired from a long workday but your friends all really would like to go out for dinner and drinks. And naturally, they want to go to the loudest restaurant (because they have amazing food and live entertainment). And you strain and struggle to understand the conversation for over an hour and a half.
But it’s very difficult and exhausting. And it’s a sign of hearing loss.
Maybe, you rationalize, the restaurant was just too loud. But no one else seemed to be having difficulties. It seemed like you were the only one experiencing trouble. So you start to wonder: Why do ears with hearing impairment have such a hard 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 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 formally called “hierarchical encoding”. Most of this process occurs in the brain. At least, that’s in accordance with a new study performed by a team at Columbia University.
Scientists have recognized for some time that human ears effectively work as a funnel: they forward all of the raw data that they gather to your brain. In the auditory cortex the real work is then accomplished. That’s the part of your gray matter that processes all those impulses, interpreting sensations of moving air into identifiable sounds.
Precisely what these processes look like was still unknown despite the existing knowledge of the role played by the auditory cortex in the process of hearing. Scientists were able, by making use of novel research techniques on individuals with epilepsy, to get a better picture of how the auditory cortex discerns voices in a crowd.
The Hearing Hierarchy
And the insight they found follows: there are two components of the auditory cortex that manage most of the work in allowing you to identify particular voices. And in noisy settings, they enable you to isolate and intensify specific voices.
- Heschl’s gyrus (HG): The first sorting phase is managed by this part of the auditory cortex. Heschl’s gyrus or HG processes each individual voice and separates them into distinguishable identities.
- Superior temporal gyrus (STG): The differentiated voices go from the HG to the STG, and it’s at this point that your brain begins to make some value distinctions. The superior temporal gyrus figures out which voices you want to give attention to and which can be securely moved to the background.
When you begin to suffer with hearing damage, it’s more difficult for your brain to distinguish voices because your ears are lacking certain wavelengths of sound (high or low, depending on 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 makes conversations hard to follow).
New Science = New Algorithm
Hearing aids currently have functions that make it easier to hear in loud settings. But now that we know what the basic process looks like, hearing aid manufacturers can incorporate more of those natural functions into their instrument algorithms. For example, hearing aids that do more to distinguish voices can assist the Heschl’s gyrus a little bit, resulting in a greater ability for you to comprehend what your coworkers are talking about in that loud restaurant.
The more we discover about how the brain works, particularly in connection with the ears, the better new technology will be able to mimic what happens in nature. And better hearing outcomes will be the outcome. That way, you can focus a little less on struggling to hear and a little more on enjoying yourself.