Sometimes when a person has a hard time hearing, someone close to them insultingly says they have “selective hearing”. Maybe you heard your mother accuse your father of having “selective hearing” when she believed he might be ignoring her.
But actually selective hearing is quite the talent, an amazing linguistic task executed by teamwork between your brain and ears.
Hearing in a Crowd
Perhaps you’ve encountered this situation before: you’ve been through a long day at work, but your friends all insist on going out to dinner. And of course, they want to go to the noisiest restaurant (because they have amazing food and live entertainment). And you strain and struggle to follow the conversation for over an hour and a half.
But it’s very difficult and exhausting. And it’s an indication of hearing loss.
Perhaps, you rationalize, the restaurant was just too noisy. But… everyone else appeared to be having a fine go of it. The only one who appeared to be having difficulty was you. So you start to ask yourself: what is it about the crowded room, the cacophony of voices all battling to be heard, that causes hearing impaired ears to struggle? It seems as if hearing well in a crowd is the first thing to go, but why? Scientists have begun to uncover the solution, and it all starts 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 happen in your ears at all. This process nearly completely occurs in your brain. At least, that’s according to a new study carried out by a team at Columbia University.
Scientists have recognized for some time that human ears basically work like a funnel: they send all of the raw data that they collect to your brain. That’s where the real work takes place, particularly the auditory cortex. Vibrations caused by moving air are translated by this part of the brain into perceptible sound information.
Because of comprehensive research with CT and MRI scans, scientists have known for years that the auditory cortex plays a crucial role in hearing, but they were clueless regarding what those processes really look like. Scientists were able, by utilizing unique research techniques on individuals with epilepsy, to get a better understanding of how the auditory cortex discerns voices in a crowd.
The Hearing Hierarchy
And the insight they found out are as follows: the majority of the work performed by the auditory cortex to isolate distinct voices is accomplished by two different parts. They’re what allows you to sort and intensify specific voices in loud settings.
- Superior temporal gyrus (STG): At some point your brain needs to make some value based decisions and this occurs in the STG after it receives the voices which were previously separated by the HG. Which voices can be safely moved to the background and which ones you want to pay attention to is figured out by the STG..
- Heschl’s gyrus (HG): This is the part of the auditory cortex that manages the first phase of the sorting routine. Heschl’s gyrus or HG breaks down each unique voice and separates them into distinguishable identities.
When you begin to suffer with hearing problems, it’s harder for your brain to differentiate voices because your ears are missing specific wavelengths of sound (low or high, depending on your hearing loss). Your brain isn’t supplied with enough information to assign individual identities to each voice. It all blends together as a result (which makes discussions tough to follow).
New Science = New Algorithm
It’s common for hearing aids to have features that make it less difficult to hear in a crowded situation. But now that we know what the fundamental process looks like, hearing aid manufacturers can integrate more of those natural functions into their instrument algorithms. For example, you will have a greater capacity to hear and understand 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 occurs in nature as we discover more about how the brain really works in conjunction with the ears. And that can lead to improved hearing success. Then you can concentrate a little more on enjoying yourself and a little less on straining to hear.