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 listened to the part about chocolate cake for dessert and (perhaps purposely) disregarded the part about cleaning your room.
But in reality it takes an incredible 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 dealt with this scenario before: you’ve been through a long day at work, but your buddies all insist on meeting up for dinner. And naturally, they want to go to the loudest restaurant (because they have amazing food and live entertainment). And you spend the entire evening straining your ears, trying to follow the conversation.
But it’s very difficult and exhausting. And it’s a sign of hearing loss.
You think, maybe the restaurant was simply too noisy. But… everyone else seemed to be having a great time. The only one who appeared to be having trouble was you. Which gets you thinking: what is it about the packed room, the cacophony of voices all struggling to be heard, that causes hearing impaired ears to struggle? Just why is it that being able to hear in a crowd is so challenging? The answer, according to scientists, is selective hearing.
Selective Hearing – How Does it Work?
The scientific name for what we’re broadly calling selective hearing is “hierarchical encoding,” and it doesn’t take place inside of your ears at all. The majority of this process occurs in the brain. At least, that’s in accordance with a new study carried out by a team at Columbia University.
Scientists have known for quite a while that human ears essentially work like a funnel: they compile all the signals and then send the raw information to your brain. In the auditory cortex the real work is then accomplished. Vibrations caused by moving air are interpreted by this part of the brain into perceptible sound information.
Exactly what these processes look like was still unknown despite the established 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 discerns voices in a crowd.
The Hierarchy of Hearing
And here is what these intrepid scientists discovered: the majority of the work done by the auditory cortex to pick out distinct voices is performed by two different parts. And in loud settings, they enable you to separate and amplify certain voices.
- Heschl’s gyrus (HG): This is the part of the auditory cortex that takes care of the first phase of the sorting routine. Scientists found that the Heschl’s gyrus (we’re just going to call it HG from here on out) was processing each distinct voice, classifying them into unique identities.
- Superior temporal gyrus (STG): Sooner or later your brain will need to make some value based choices and this is done in the STG once it receives the voices which were previously differentiated by the HG. The superior temporal gyrus figures out which voices you want to focus on and which can be securely 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 certain wavelengths of sound (low or high, depending on your hearing loss). Your brain isn’t furnished with enough data to assign separate identities to each voice. It all blurs together as a result (which means conversations will harder to follow).
New Science = New Algorithm
It’s standard for hearing aids to come with functions that make it less difficult to hear in a crowd. But now that we understand what the fundamental process looks like, hearing aid makers can integrate more of those natural functions into their instrument algorithms. For instance, you will have a greater capacity to hear and comprehend what your coworkers are talking about with hearing aids that help the Heshl’s gyrus and do a little more to separate voices.
Technology will get better at mimicking what takes place in nature as we uncover more about how the brain functions in conjunction with the ears. And that can result in better hearing success. Then you can focus a little more on enjoying yourself and a little less on straining to hear.