Selective hearing is a term that commonly 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 (maybe intentionally) ignored the part about cleaning your room.

But actually selective hearing is quite the skill, an impressive linguistic accomplishment executed by cooperation between your ears and brain.

The Difficulty Of Trying to Hear in a Crowd

This situation potentially seems familiar: you’re feeling tired from a long day at work 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 deep-fried cauliflower is delicious). And you strain and struggle to follow the conversation for the entire evening.

But it’s very difficult and exhausting. And it’s a sign of hearing loss.

You think, perhaps the restaurant was just too loud. But no one else seemed to be having difficulties. The only person who appeared to be having difficulty was you. Which makes you think: what is it about the crowded room, the cacophony of voices all battling to be heard, that throws hearing-impaired ears for a loop? Just why is it that being able to hear in a crowd is so quick to go? Scientists have started to discover the answer, and it all begins with selective hearing.

Selective Hearing – How Does it Work?

The term “selective hearing” is a task that doesn’t even happen in the ears and is formally called “hierarchical encoding”. The majority of this process occurs in the brain. At least, that’s in accordance with a new study done by a team from Columbia University.

Ears work like a funnel as scientists have understood for quite a while: they forward all of the raw data that they gather to your brain. That’s where the heavy lifting takes place, specifically the auditory cortex. That’s the part of your gray matter that processes all those impulses, interpreting impressions of moving air into recognizable sounds.

Precisely 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 hearing process. Scientists were able, by using unique 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 facts they found follows: there are two parts of the auditory cortex that accomplish most of the work in helping you identify particular voices. And in loud situations, they enable you to isolate and enhance specific voices.

• Heschl’s gyrus (HG): The first sorting stage is taken care of by this region of the auditory cortex. Researchers observed that the Heschl’s gyrus (we’re just going to call it HG from here on out) was processing each individual voice, separating them into individual identities.
• Superior temporal gyrus (STG): Sooner or later your brain needs to make some value based choices and this happens in the STG once it receives the voices that were previously separated by the HG. The superior temporal gyrus figures out which voices you want to pay attention to and which can be confidently moved to the background.

When you have hearing problems, your ears are missing specific wavelengths so it’s harder for your brain to distinguish voices (depending on your hearing loss it might be high or low frequencies). Your brain isn’t supplied with enough data to assign individual identities to each voice. It all blends together as a result (which makes interactions difficult to follow).

New Science = New Algorithm

Hearing aids currently have functions that make it easier to hear in loud circumstances. But hearing aid makers can now incorporate more of those natural functions into their algorithms because they have a better concept of what the process looks like. For example, you will have a greater capacity to hear and comprehend what your coworkers are talking about with hearing aids that assist the Heshl’s gyrus and do a little more to differentiate voices.

The more we discover about how the brain works, especially in conjunction with the ears, the better new technology will be able to mimic what happens in nature. And better hearing success will be the result. That way, you can concentrate a little less on struggling to hear and a little more on enjoying yourself.