Sometimes when a person has a difficult time hearing, someone close to them insultingly suggests they have “selective hearing”. Maybe you heard your mother suggest that your father had “selective hearing” when she believed he was ignoring her.
But actually it takes an amazing act of cooperation between your brain and your ears to have selective hearing.
The Stress Of Trying to Hear in a Crowd
Perhaps you’ve experienced this situation before: you’ve had a long day at work, but your friends all insist on going out to dinner. They pick the loudest restaurant (because it’s trendy and the food is the best in town). And you spend the entire evening straining your ears, attempting 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 noisy. But… everyone else seemed to be having a great time. You seemed like the only one having trouble. So you start to ask yourself: Why do ears that have hearing impairment have such a difficult time with the noise of a packed room? It seems as if hearing well in a crowded place is the first thing to go, but what’s the reason? Scientists have begun to discover the solution, and it all starts with selective hearing.
How Does Selective Hearing Work?
The phrase “selective hearing” is a task that doesn’t even happen in the ears and is formally known as “hierarchical encoding”. This process nearly exclusively happens in your brain. At least, that’s in accordance with a new study done by a team at Columbia University.
Scientists have known for quite some time that human ears essentially work as a funnel: they compile all the signals and then send the raw data to your brain. That’s where the real work occurs, specifically the auditory cortex. Vibrations caused by moving air are translated by this part of the brain into perceptible sound information.
Because of extensive research with MRI and CT 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 using unique research techniques on people with epilepsy, to get a better picture of how the auditory cortex picks out voices in a crowd.
The Hearing Hierarchy
And here is what these intrepid scientists discovered: there are two components of the auditory cortex that accomplish most of the work in allowing you to identify specific voices. They’re what enables you to sort and intensify specific voices in loud settings.
- Heschl’s gyrus (HG): This is the region of the auditory cortex that handles the first stage of the sorting process. Heschl’s gyrus or HG processes each individual voice and separates them into discrete identities.
- Superior temporal gyrus (STG): At some point your brain needs to make some value based choices and this occurs in the STG once it receives the voices which were previously differentiated by the HG. The superior temporal gyrus determines which voices you want to pay attention to and which can be confidently moved to the background.
When you begin to suffer from hearing problems, it’s harder for your brain to distinguish voices because your ears are missing particular wavelengths of sound (depending on your hearing loss it could be high or low frequencies). Your brain can’t assign individual identities to each voice because it doesn’t have enough data. It all blends together as a consequence (meaning conversations will harder to understand).
New Science = New Algorithm
Hearing aids currently have functions that make it easier to hear in loud situations. But now that we know what the basic process looks like, hearing aid makers can incorporate 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 talking about in that loud restaurant.
Technology will get better at mimicking what occurs in nature as we learn more about how the brain works in conjunction with the ears. And that can result in improved hearing outcomes. Then you can focus a little more on enjoying yourself and a little less on straining to hear.