Why Can’t I Hear in a Crowd?

Selective hearing is a term that normally gets tossed about as a pejorative, an insult. Maybe you heard your mother accuse your father of having “selective hearing” when she believed he was ignoring her.

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

The Difficulty Of Trying to Hear in a Crowd

This situation probably feels familiar: you’ve been through a long day at work, but your buddies all insist on meeting up for dinner. And of course, they want to go to the loudest restaurant (because it’s popular 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. This indicates that you could have hearing loss.

You think, maybe the restaurant was simply too noisy. But.. everyone else appeared to be having a great time. The only person who appeared to be having trouble was you. So you begin to ask yourself: what is it about the crowded room, the cacophony of voices all trying to be heard, that throws hearing-impaired ears for a loop? It seems as if hearing well in a crowded place is the first thing to go, but why? Scientists have begun to discover the answer, and it all begins with selective hearing.

How Does Selective Hearing Operate?

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

Scientists have known for quite a while that human ears basically work like a funnel: they forward 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 impulses, interpreting sensations of moving air into recognizable sounds.

Because of significant research with MRI and CT scans, scientists have known for years that the auditory cortex plays a considerable role in hearing, but they were clueless 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 understanding of how the auditory cortex discerns voices in a crowd.

The Hierarchy of Hearing

And the facts they discovered follows: there are two components of the auditory cortex that manage most of the work in allowing you to key in on individual voices. And in loud situations, they allow you to isolate and intensify specific voices.

• Superior temporal gyrus (STG): Sooner or later your brain will need to make some value based choices and this is done in the STG after it receives the voices which were previously separated by the HG. The superior temporal gyrus figures out which voices you want to give attention to and which can be securely moved to the background.
• 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 distinct identities.

When you begin to suffer from hearing damage, it’s harder for your brain to differentiate voices because your ears are lacking certain wavelengths of sound (depending on your hearing loss it might be high or low frequencies). Your brain isn’t furnished with enough information to assign individual identities to each voice. It all blends together as a consequence (meaning interactions will harder to follow).

New Science = New Algorithm

It’s standard for hearing aids to come with functions that make it easier to hear in a crowd. But now that we know what the basic process looks like, hearing aid companies can incorporate more of those natural operations into their device algorithms. For instance, you will have a better ability to hear and understand what your coworkers are saying 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 conjunction with the ears, the better new technology will be capable of mimicking what happens in nature. And better hearing outcomes will be the outcome. Then you can concentrate a little more on enjoying yourself and a little less on straining to hear.