The Science of Silence

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In a world full of noise and increasing stimulation, it can sometimes seem like it can get all too much. However, for some, it’s more than just an annoyance of having too much to listen to, it can become limiting, distressing and outright painful. This sensory overload has driven scientists to try to understand the science of silence.

Sensory overload, as with many disabilities, can be severely debilitating for a person who suffers from it and functioning in this information overloaded, noisy, busy world that we have created can be incredibly difficult. There are now movements to steer us back to a more peaceful time, such as supermarkets who have been trialling a ‘Quiet Hour’ for autistic shoppers. Asda trialled this last year and now other stores such as Tesco are following suit.

However, one hour a week is hardly accommodating for a 24/7 disability. Here is just one person’s description of how sensory overload affects them taken (from Austism.org.uk):

If I already have things going on, building up, or even just when I am trying to concentrate and there is noise, I quickly crumble. I feel my body heat up – a fire up my neck, across my face and then all over. My face goes red and my heart rate flies up.

Clearly we need more than a silent hour and that is where science and technology can come to the rescue. You may own, or know someone who owns, a pair of noise cancelling headphones that rid you of all those pesky background noises of modern life so you can listen to your music in peace. Well these very same headphones can be a huge help for people who suffer from too much noise.

These headphones create silence, but how does that even work? It appears to be an impossible task. It is quite literally taking something, noise caused through sound vibrations, and making nothing out of it. Luckily it’s not as hard as this train of thought suggests. First of all, let’s take a look at a simple wave:

Credit: Hermione Cook

This wave represents a noise that we hear from a source, say a phone. Now if we had two phones making the same noise, then it will be twice as loud. We take two of these waves and add them together to give us this:

Credit: Hermione Cook

Here we can see it is simply double in height (or volume). So if we take a wave that is opposite to the original wave as such:

Credit: Hermione Cook
Credit: Hermione Cook

Then when we add together you can see that they will cancel each other out and we will have nothing, silence.

The tricky part here is creating a wave that is equal and opposite to whatever noise we start with. This is where the headphones have to have more technology than your normal pair of beats. They analyse the sound from their surroundings and works out a profile of the sound waves detected. Then they make their own sound waves (even more noise then we started with) to cancel out the original sound waves to make silence. It seems counter intuitive but works surprisingly well. With these headphones the same person above comments:

If I can wear my headphones and blast music through my ears in the gym, down the street, on the bus. I can cope.

It’s not a full solution, but it’s definitely a step in the right direction. So next time you put on your fancy headphones, take a moment, and appreciate the silence.

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