Sometimes when a person has a hard time hearing, someone close to them insultingly suggests they have “selective hearing”. Perhaps you heard your mother accuse your father of having “selective hearing” when she suspected he was ignoring her.
But actually it takes an incredible act of cooperation between your ears and your brain to have selective hearing.
Hearing in a Crowd
Perhaps you’ve dealt with this scenario before: you’ve had a long day at work, but your friends all insist on meeting up for dinner. They choose the loudest restaurant (because they have incredible food and live entertainment). And you strain and struggle to follow the conversation for the entire evening.
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 no one else appeared to be struggling. The only person who appeared to be having trouble was you. Which makes you think: Why do ears with 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? The answer, according to scientists, is 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 almost entirely takes place in your brain. At least, that’s as reported by a new study performed by a team at Columbia University.
Scientists have known for some time that human ears effectively work like a funnel: they collect all the impulses and then deliver the raw data to your brain. That’s where the real work occurs, specifically the auditory cortex. That’s the part of your brain that handles all those impulses, translating sensations of moving air into perceptible sounds.
Because of comprehensive research with CT and MRI scans, scientists have recognized for years that the auditory cortex plays a significant role in hearing, but they were stumped 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 understanding of how the auditory cortex discerns voices in a crowd.
The Hierarchy of Hearing
And here’s what these intrepid scientists learned: the majority of the work accomplished by the auditory cortex to isolate particular voices is done by two different regions. They’re what enables you to sort and intensify specific voices in noisy environments.
- Heschl’s gyrus (HG): The first sorting phase is handled by this region of the auditory cortex. Researchers discovered that the Heschl’s gyrus (we’re simply going to call it HG from now on) was breaking down each unique voice, separating them via individual identities.
- Superior temporal gyrus (STG): At some point your brain needs to make some value based decisions and this is done in the STG after 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 lacking particular wavelengths so it’s harder for your brain to recognize voices (high or low, depending on your hearing loss). Your brain can’t assign individual identities to each voice because it doesn’t have enough data. As a result, it all blurs together (meaning conversations will more difficult to understand).
A New Algorithm From New Science
Hearing aids currently have functions that make it less difficult to hear in loud environments. 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 instance, you will have a better ability 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 identify voices.
The more we discover about how the brain works, specifically in connection with the ears, the better new technology will be able to mimic what takes place in nature. And that can lead to better hearing success. That way, you can concentrate a little less on struggling to hear and a little more on enjoying yourself.
