Sometimes when a person has a difficult time hearing, somebody close to them insultingly says they have “selective hearing”. Perhaps you heard your mother suggest that your father had “selective hearing” when she suspected he might be ignoring her.
But actually selective hearing is quite the ability, an amazing linguistic accomplishment executed by cooperation between your ears and brain.
Hearing in a Crowd
This scenario probably feels familiar: you’ve been through a long day at work, but your buddies all insist on going out to dinner. They choose the loudest restaurant (because it’s popular and the food is delicious). And you strain and struggle to understand the conversation for over an hour and a half.
But it’s very difficult and exhausting. And it’s an indication of hearing loss.
You think, maybe the restaurant was just too loud. But no one else appeared to be struggling. The only one who appeared to be having difficulty was you. So you start to ask yourself: Why do ears with hearing impairment have such a hard time with the noise of a crowded room? It seems as if hearing well in a crowded place is the first thing to go, but why? Scientists have started to uncover the answer, and it all begins with selective hearing.
Selective Hearing – How Does it Work?
The term “selective hearing” is a process that doesn’t even occur in the ears and is technically known as “hierarchical encoding”. This process nearly entirely takes place in your brain. At least, that’s as reported by a new study performed by a team at Columbia University.
Ears work like a funnel which scientists have recognized for some time: they deliver all of the raw data that they gather to your brain. In the auditory cortex the real work is then done. That’s the part of your gray matter that processes all those signals, translating impressions of moving air into recognizable sounds.
Because of extensive research with CT and MRI scans, scientists have understood for years that the auditory cortex plays a substantial role in hearing, but they were stumped when it came to what those processes really look like. Scientists were able, by making use of novel 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 here is what these intrepid scientists discovered: there are two parts of the auditory cortex that perform most of the work in helping you identify distinct voices. And in loud environments, they allow you to separate and enhance specific voices.
- Superior temporal gyrus (STG): The differentiated voices move from the HG to the STG, and it’s here that your brain begins to make some value determinations. Which voices can be freely moved to the background and which ones you want to focused on is determined by the STG..
- Heschl’s gyrus (HG): The first sorting phase is managed by this region of the auditory cortex. Heschl’s gyrus or HG processes each unique voice and separates them into distinguishable identities.
When you have hearing loss, your ears are lacking specific wavelengths so it’s more difficult for your brain to differentiate voices (low or high, depending on your hearing loss). Your brain isn’t provided with enough data to assign individual identities to each voice. Consequently, it all blurs together (which makes discussions tough to follow).
New Science = New Algorithm
It’s typical for hearing aids to come with features that make it easier to hear in a crowded situation. But now that we know what the fundamental process looks like, hearing aid makers can integrate more of those natural operations into their device algorithms. For instance, hearing aids that do more to distinguish voices can assist the Heschl’s gyrus a little, bringing about a greater ability for you to comprehend what your coworkers are saying in that loud restaurant.
The more we learn about how the brain works, particularly in conjunction with the ears, the better new technology will be capable of mimicking what happens in nature. And better hearing success will be the result. Then you can focus a little more on enjoying yourself and a little less on straining to hear.
