Sometimes when an individual has a difficult time hearing, somebody close to them insultingly says they have “selective hearing”. Maybe you heard your mother suggest that your father had “selective hearing” when she believed he might be ignoring her.

But actually it takes an amazing act of cooperation between your ears and your brain to have selective hearing.

The Stress Of Trying to Hear in a Crowd

This scenario probably seems familiar: you’re feeling burnt out from a long workday but your friends all really want to go out for dinner and drinks. They choose the loudest restaurant (because it’s popular and the deep-fried cauliflower is the best in town). And you strain and struggle to understand the conversation for over an hour and a half.

But it’s very difficult and exhausting. This indicates that you could have hearing loss.

You think, maybe the restaurant was just too loud. But no one else seemed to be struggling. The only person who appeared to be having difficulty was you. Which makes you think: what is it about the packed room, the cacophony of voices all trying to be heard, that throws hearing-impaired ears for a loop? It seems like hearing well in a crowded place is the first thing to go, but what’s the reason? Scientists have started to discover the answer, and it all starts with selective hearing.

Selective Hearing – How Does it Work?

The phrase “selective hearing” is a process that doesn’t even happen in the ears and is formally known as “hierarchical encoding”. Most of this process occurs in the brain. At least, that’s as reported by a new study carried out by a team from Columbia University.

Scientists have recognized for quite a while that human ears effectively work like a funnel: they gather all the signals and then deliver the raw data to your brain. That’s where the heavy lifting happens, specifically the auditory cortex. That’s the part of your gray matter that processes all those signals, interpreting sensations of moving air into identifiable sounds.

Because of considerable research with CT and MRI scans, scientists have recognized for years that the auditory cortex plays a substantial role in hearing, but they were clueless when it came to what those processes actually look like. Scientists were able, by making use of unique research techniques on people with epilepsy, to get a better picture of how the auditory cortex discerns voices in a crowd.

The Hearing Hierarchy

And here is what these intrepid scientists learned: the majority of the work performed by the auditory cortex to pick out specific voices is accomplished by two separate parts. And in noisy environments, they allow you to separate and enhance certain voices.

• Heschl’s gyrus (HG): This is the region of the auditory cortex that handles the first stage of the sorting routine. Heschl’s gyrus or HG processes each unique voice and separates them into distinct identities.
• Superior temporal gyrus (STG): At some point your brain will need to make some value based choices and this occurs in the STG once it receives the voices that were previously differentiated by the HG. The superior temporal gyrus figures out which voices you want to give attention to and which can be safely moved to the background.

When you begin to suffer from hearing impairment, it’s more difficult for your brain to distinguish voices because your ears are lacking certain wavelengths of sound (low or high, depending on your hearing loss). Your brain isn’t provided with enough data to assign separate identities to each voice. As a result, it all blurs together (which means interactions will harder to follow).

A New Algorithm From New Science

Hearing aids already have functions that make it easier to hear in loud environments. But hearing aid manufacturers can now incorporate more of those natural functions into their algorithms because they have a better idea of what the process looks like. For instance, hearing aids that do more to distinguish voices can help out the Heschl’s gyrus a little bit, bringing about a greater capacity for you to understand what your coworkers are saying in that loud restaurant.

The more we find out about how the brain works, especially in combination with the ears, the better new technology will be capable of mimicking what happens in nature. And better hearing outcomes will be the result. Then you can concentrate a little more on enjoying yourself and a little less on straining to hear.