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Hearing: It's More Than Ears, It's Skin Deep

Our bodies are bombarded every day with what scientists call sensory stimuli – sights, sounds, tastes, touches and smells; and all deliver sensory input to the brain endlessly throughout each day. Even when you’re sitting in complete silence, alone at home, you still pick up sights, sounds and other stimuli delivered via your five senses – sight, hearing, taste, smell and touch.

It’s too hot or too cold. Something smells good (and it’s coming from the kitchen!), it’s getting dark out, a car just drove by, the couch is lumpy – even when we’re sitting quietly, we still receive stimuli – sensory input – from all parts of the body.

In fact, did you know that you not only hear sounds with your ears but also with your skin? Snakes do so why not humans.

It’s all About the Brain

Hearing loss communication
Facial expressions and body language speak for themselves

You’re reading this. Your eyes scan the words. These symbols, which you’ve learned to recognize, are delivered to the brain where they’re interpreted. That’s how we’re communicating right now. I’m writing symbols that have meaning (maybe not to my editor) and you read those symbols and you understand the words I write. Simple, right?

Well, in fact, it’s anything but simple. Studies, recently published by the University of Toronto, and discussed in the New York Times, paint a much more complex picture of how we interact with the world around us.

Let’s go back a few years to 1976 when an important study was undertaken and the results published. That study, and lots of studies that came later, show that we use all of our senses in combination to communicate with the world and the people who share the world with us.

For example, the expression on your boss’ face may reveal much more than the words you’re hearing. You pick up visual cues from facial expression and body language – how the individual reacts physically to what s/he is saying. The body doesn’t lie. These are ingrained movements and gestures of which we may not even be aware – at least on the most conscious level.

Sure, if your boss raises her voice or change her tone of voice that’s an expression you pick up with your ears – the sense of hearing. Psychologists believe that the senses of sight and hearing are the two most critical in interpreting sound but a recent study also indicates that the skin is also involved in the listening experience, all of which takes place in the brain.

The New York Times reports on a study, conducted at the University of British Columbia conducted by Bryan Gick and Donald Derrick, that people hear with their skin as well as with their ears. See, it’s more complicated than you thought.

According to The Times article, “The researchers had subjects listen to spoken syllables while hooked up to a device that would simultaneously blow a tiny puff of air onto the skin of their hand or neck. The syllables included “pa” and “ta,” which produce a brief puff from the mouth when spoken, and “da” and “ba,” which do not produce puffs. They found that when listeners heard “da” or “ba” while a puff of air was blown onto their skin, they perceived the sound as “ta” or “pa.”

The researchers pointed out that the findings were similar to those released in 1976 that showed that visual and sound cues played a role in understanding the people around us. Dr. Gick explained that the results of the U of BC study showed that, even though people heard one set of sounds, that light puff of air on their skin caused their brains to interpret what was actually heard differently.

In this particular situation, the sensory input on the skin was used in conjunction with what was heard. Because the two conflicted (the puff and what was actually heard – “ba”), the brain made the decision is it “pa” or “ba” based on the input (the puff) felt on the skin since when “pa” is spoken, a slight puff of air is produced (something the brain intuitively knows).

Now, you might not feel that light breeze when listening to a speaker who’s far away, but your brain is programmed to recognize those “puffy” sounds and to interpret them as certain syllables – even when the actual sounds you hear are different.

This study shows the important role the brain plays in what’s called sensory integration – using all of the five senses to accurately interpret what’s going on around you in the day-to-day world.

Sensory Integration Made Simple

human hearing diagram
Human hearing diagram. Photo courtesy: Sonic Innovations

When a sound is made, you don’t hear it immediately. In fact, you don’t hear it until the sound waves have made their way to your ears and are funneled down the ear canal by the outer ear.

Inside the ear, the ear drum (tympanic membrane) vibrates to the exact rhythm of the sound that was made – but you still haven’t heard that sound yet. The ear drum vibrates, shaking three small bones called the anvil, the hammer and the stirrup bones – the three smallest bones in the human body.

The vibrations created by the sound pass through the three bones which vibrate a tiny organ deep inside the ear called the cochlea. The cochlea, a snail-shaped organ, is filled with a thick fluid and lined on the inside with hundreds of thousands of hair like projections waving back and forth in the fluid. (You still haven’t heard the sound yet, but it’s coming.)

The cochlear fluid vibrates, activating those hair-like projections. These projections have the miraculous ability to turn mechanical energy – the sound wave vibrations – into electrical energy that’s delivered to the brain’s hearing centers. And, nope, you still haven’t heard the sound.

Once in the brain, the hearing centers identify the sound, call on the brain’s memory banks to recognize the sound ( a dog barking, a horn honking, etc.) and to localize the sound, i.e. determine where it’s coming from. That’s why you can pinpoint the sound of a tweeting bird a hundred yards away in a tree. Your brain’s hearing centers interpret the sound so you can identify what the sound is and where it’s coming from.

Only after the mechanical sound waves have been converted into electrical impulses and sent to the brain for processing do you actually hear the sound. It all happens in the brain.

The British Columbia study confirms other studies that prove that understanding the world around you involves the integration of input delivered by all the senses – including the sense of touch. The slight puff of air across the skin caused people to mis-identify the actual test sounds used during this research. They heard a spoken syllable, felt the puff of air simultaneously and interpreted the sounds based on the sensation of touch, not sound.

So, we take in sensory stimulation through our five senses. This information must then be converted into electrical signals that the brain can understand. Once all the data is collected from all the senses, the brain takes in to account all these stimuli and determines our world around us.

And it does it all in a split second. Think about it. When someone talks to you, face to face, your brain is picking up all kinds of sensory clues. Your ears are delivering sound waves through the hearing system to the brain. Your eyes are picking up visual clues – facial expressions and body language. Your skin is picking up signals as you speak words. You may not feel the puffs of air produced by a distant speaker but you feel your own puffy sounds instantaneously.

It’s the brain’s ability to integrate all of these different stimuli that enable us to interpret what’s going on around us. Are we in danger? Should we be happy? Is the speaker being sarcastic? Are those chocolate chip cookies baking in the oven? All of this sensory input is delivered to the brain, integrated, analyzed and assimilated – all in the blink of an eye.

And you thought hearing was so simple.

What Does This Mean To You?

Well, beside the fact that the human brain is a true natural wonder, there are some other take-aways from this recent study and the studies that preceded it.

First, you can’t always judge a book by its cover. In other words, you require all five senses to judge that book, not just your eyes. It’s the brains ability to integrate all manner of sensory input that enables us to make it through the day without getting run over by a car or setting the house on fire. Thank goodness for our senses. And our brains.

Second, we’re more apt to miss cues when we’re distracted. If you aren’t looking directly at the speaker, you might miss the rolling of the eyes when he speaks or the scrunching of the nose. It’s important to understanding our world that all senses be engaged simultaneously. No worries, the brain can handle a bunch of stimuli from all your senses to warn of everything from danger to love is in the air.

The third take-away is perhaps the most interesting. This British Columbia study points out the importance of sensory integration in accurately interpreting sounds, sights, smells, touches and tastes. But it all happens while we’re on auto-pilot. We don’t have to think about sounds or sights and how they fit together. It happens instantly. Without a thought.

That means that the brain receives a lot of input that we’re not even aware of. Because the brain is able to integrate all of this sensory input so quickly and automatically, we may not be tuned in to all that we see or hear, taste, touch or smell.

But what happens if we have hearing loss and unable to hear fine details in the sounds around us, most importantly speech sounds. What if we have poor vision and are unable to see visual cues when communicating in background noise.

Treating hearing loss is just as important as treating vision loss to ensure our brain does not miss a beat when piecing together the complex puzzle we call life.

Should You Have Your Hearing Tested?

Think about it.

Are you missing sounds, or is your brain misinterpreting sounds because you are not hearing the whole picture? Do you subconsciously strain to see the speakers face while they are speaking for visual cues? When you’re watching a movie, do you have a hard time hearing what a character says when you can’t see her face? These are cognitive cues that you may be experiencing hearing loss.

Look, if your eyesight gets so bad that you have to hold the newspaper at arms length to read it, you have your eyes checked and you get yourself a pair of reading glasses. Problem solved.

However, hearing loss often happens so gradually we miss it – until we literally MISS it. We adapt our behaviors to compensate for that hearing loss. Simple. We turn up the TV or MP3 player and don’t give it a thought. We say “what” a lot and annoy those close to us.

Well, engage the cognitive side of your brain for a minute. Think about your hearing. Think about how you may have adapted to hearing loss by using your other senses to compensate.

If your hearing isn’t running on all cylinders, you’ll notice it once you become aware of changes in your behavior – changes that enable you to hear the world around you through visual cues and puffs of air moving across the skin. And when the cognitive (thinking) center of your brain concludes that, indeed, you have experienced hearing loss, what do you do about it?

Make an appointment for a hearing test. It is a simple, quick and non-invasive test which will determine if you do in fact have hearing loss. Based on the results treatment options will be discussed such as hearing aids or other assistive listening devices.

You have no idea what you have potentially been missing And after all, you don’t know what you’ve got until its gone.

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