Selective hearing is a term that commonly gets tossed about as a pejorative, an insult. Perhaps you heard your mother accuse your father of having “selective hearing” when she thought he might be ignoring her.
But in reality it takes an amazing act of teamwork between your brain and your ears to have selective hearing.
Hearing in a Crowd
Perhaps you’ve dealt with 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. They choose the noisiest restaurant (because they have great food and live entertainment). And you spend the entire evening straining your ears, working hard to follow the conversation.
But it’s very difficult and exhausting. And it’s a sign of hearing loss.
Maybe, you rationalize, the restaurant was simply too loud. But… everyone else seemed to be having a great time. You seemed like the only one experiencing trouble. So you start to ask yourself: Why do ears that have hearing impairment have such a hard 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 begun to discover the solution, and it all starts with selective hearing.
Selective Hearing – How Does it Work?
The term “selective hearing” is a task that doesn’t even occur in the ears and is formally called “hierarchical encoding”. This process almost entirely happens in your brain. At least, that’s according to a new study done by a team from Columbia University.
Scientists have known for quite a while that human ears effectively work like a funnel: they compile all the signals and then forward the raw data to your brain. In the auditory cortex the real work is then accomplished. Vibrations triggered by moving air are interpreted by this part of the brain into recognizable sound information.
Just what these processes look like had remained a mystery in spite of the established knowledge of the role played by the auditory cortex in the hearing process. Scientists were able, by utilizing novel research techniques on people with epilepsy, to get a better understanding of how the auditory cortex discerns voices in a crowd.
The Hierarchy of Hearing
And here’s what these intrepid scientists learned: there are two components of the auditory cortex that perform most of the work in helping you key in on individual voices. They’re what enables you to separate and amplify specific voices in loud environments.
- Superior temporal gyrus (STG): Eventually your brain will need to make some value based decisions and this is done in the STG after it receives the voices that were previously differentiated by the HG. Which voices can be safely moved to the background and which ones you want to focused on is determined by the STG..
- Heschl’s gyrus (HG): The first sorting stage is handled by this part of the auditory cortex. Researchers observed that the Heschl’s gyrus (we’re just going to call it HG from now on) was processing each distinct voice, classifying them via unique identities.
When you begin to suffer from hearing impairment, it’s harder for your brain to differentiate voices because your ears are lacking particular wavelengths of sound (depending on your hearing loss it might be low or high frequencies). Your brain isn’t provided with enough information to assign separate identities to each voice. As a result, it all blends together (meaning interactions will more difficult to follow).
New Science = New Algorithm
It’s common for hearing aids to have functions 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 incorporate more of those natural operations into their instrument algorithms. As an example, you will have a greater ability to hear and comprehend what your coworkers are saying with hearing aids that assist the Heshl’s gyrus and do a little more to differentiate voices.
Technology will get better at mimicking what occurs in nature as we discover more about how the brain works in combination with the ears. And that can lead to improved hearing outcomes. That way, you can focus a little less on struggling to hear and a little more on enjoying yourself.