Noise pollution: How the world has forgotten to listen

Noise, like the saturation of 21st century urban life, can keep our bodies in a state of alarm, or can help our brains grow stronger, scientist Nina Kraus says.

She has written Of Sound Mind: How Our Brain Constructs a Meaningful Sonic World, a book explaining how we all hear things differently and how sound affects us in ways we probably don't even realise.

Making meaning out of sound is a big ask of our brains, and right now there is arguably more noise in the world than ever before.

Kraus is a neurobiology professor specialising in audiology at Northwestern University in Illinois, one of the leading research universities in the US. Her research is widely cited, and she pioneered our understanding of the potential for the adult nervous system to reorganise itself as we learn new things.

She told Jim Mora our lives shape how we interpret things - how we hear.

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Sound is essential in connecting us and bringing us together, she said.

"The languages we speak, the music we make, the noise that we encounter, they make us us, biologically.

"As I'm talking to you now the neurons in your brain are producing electricity, because electricity is the currency of the nervous system, and we can pick up that electricity with sensors - electrodes on the head.

"I can measure your brain's response to a tune or speech ... we are actually able to see the sound as well as to play it back, but each one of us does it in our own way."

Kraus' book includes examples of the effects of noise on the brain like Benedictine monks whose health was restored when they were allowed to chant again, and sufferers of Tourettes Syndrome whose nervous systems seemed to align when they all drummed together.

Music can be therapeutic, she said, and on the one hand we need lots of music in our lives, on the other hand it's not good to be saturated with music when we don't choose.

"The last chapter of my book is my call to action: I don't want to have to listen to music - whether I like it or not - as I'm in a store or at an airport, or wherever I am, I would like to not have to have that sound imposed on me."
 
Our brains' efforts to keep up with sorting those sounds is wearying.

Despite the well-discussed soundscape of rural life not actually being an unrealistic state of complete peace and quiet, Kraus said it still presents a less stress-inducing sound environment.

"Agrarian life is not suffused with constant relentless pervasive noise, but the noises present - roosters, tractors etcetera, have purpose."

Music is widely played in public spaces in the belief it will be soothing, but Kraus said while some music may be soothing for some, it will likely be jarring for other groups.  

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"There's so much sound that is going on, that you think you're not paying attention to - for example when your refrigerator turns off or the truck idling outside that turns off its ignition - you didn't even realise those sounds were there until they were turned off, but then you breath this [sigh].

"So without even without our knowing, we are in a constant state of alarm because our hearing sense is the one that alerts us to danger."

The constant saturation is overstimulating and decreases our ability to take stock of who we are and where we are.

"Because the hearing brain is so connected to how we think and how we move and how we feel, the noise that is in our world is getting in the way of our ability to think, gets in the way of our ability to focus, gets in the way of our ability to be calm.

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"There have been good studies on this showing that children learn better when their classroom faces a quiet field, compared to the same school - they controlled for the same teachers, when the students were on the other side of the school right next to the subway."

Because our world is inherently flooded with sound, we have lost some of our ability to listen to our environment, and depend more on our visual sense.

Music has also been underappreciated for its influence on brain development, and children's achievement levels.

Kraus has worked with teams running longitudinal studies in economically disadvantaged areas of Chicago and Los Angeles.

She said those working with the children reported that those making music were the better students, but they set out to find out what was happening.

"We can see signs of linguistic understimulation with some under-representation of certain timings and harmonics and sound that are important for speech as well as for music.

"We followed children who were in these music programmes ... the kids who make music regularly over years, their brain's response - that we can measure - their brain's response to sound and these important ingredients that we know are important for speech and language, they became strengthened."

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The potential positive benefits aren't limited to the young. As we become older it becomes more difficult to hear in noisy environments, Kraus said, but those who practice sound-intensive activities like making music are better able to interpret sounds in noisy environments.

"It doesn't matter when you start, your brain is able to change its response to sound throughout our lives. We learn differently at different times in our lives, but we can begin to start playing a musical instrument later in life, and see that our brains response to sound will continue to change.

"As you strengthen your sound mind you're strengthening your ability to think, to move, to combine information from your other senses."