Colored Noise, and How It Can Help You Focus

When we think about colors, we normally connect
them with light – things you can see, like white clouds, pink flowers, and brown cows. But color can also be used to describe some
special sounds: white, pink, and brown noise. They’re very specific types of the kind
of noise you’d probably think of as static, designed to sound a certain way based on the
physiology of human hearing. And because of human evolution, they can also
be useful when you’re trying to concentrate. Have a listen to this: [PLAY WHITE]. This is white noise. Both light and sound are made of waves. The frequency of the waves – how quickly
they vibrate – are important in how we perceive them. You might know that white /light/ is made
up of light of all the colors of the rainbow – all frequencies we can /see/. White /noise/ gets its name because it contains
sounds from all across the frequencies we can /hear/. That’s a big range – from around 20 to
20,000 Hertz, or wave vibrations per second. These frequencies are played in fast, random
succession, and your brain combines these random, fast-changing frequencies into a fuzzy
hiss of static. Now, you may have noticed that white noise
sounds kind of high-pitched. Which seems weird: if white noise is made
up of sounds with totally random frequencies, you’d think it would sound sort of … middle-pitched. The reason white noise sounds high-pitched
has to do with your biology – the way your ears and brain detect and process sound. What you hear as /pitch/ isn’t quite the
same as the objective frequencies produced and detected by machines. Your hearing system — and music — is based
on octaves. When you play a string of notes, each one
octave apart — like a row of Cs [PLAY Cs] — it might sound like the are evenly spaced,
in terms of how high they are. But that’s not actually the case. Instead, each octave represents a /doubling/
in frequency, meaning there are /twice/ as many possible frequencies for our random sampler
to choose from. So in a random set of frequencies, statistically,
more of the sounds will seem higher-pitched to the human ear. And there’s another reason white noise sounds
high-pitched: human anatomy makes us more attuned to sounds in the high-ish region of
3 to 4 kilohertz. Our brains amplify sounds in this higher-pitched
region, making the higher frequency sounds in white noise seem louder than they really
are. So if you find white noise [PLAY WHITE] a
bit too tinny, you might prefer other color sounds. Like pink noise: [PLAY PINK]. Pink noise takes human hearing into account,
and balances out the frequencies so that all octaves are represented evenly. In pink noise, the frequencies played are
still random, but the /volume/ of the higher frequencies is dampened. The higher the frequency, the more the volume
is lowered, which compensates for how often the higher sounds are played. To your ears, the different pitches come through
equally strong and the result is a deeper, more balanced listening experience. /Brown noise/ takes this idea a step further,
sapping even more volume from the higher frequencies. This creates a more bassy rumble, like this
[PLAY BROWN], which sounds a bit like a large waterfall or distant
traffic. Now, if you just glanced worriedly down at
your pants, you’ve probably heard about the infamous “brown note”. Supposedly, there’s a particular tone that’s
too low for humans to hear, but apparently vibrates through your body, including your
bowels — causing involuntary motions down there! Do not worry though, you and your rear-end
can rest assured: this myth has been well and truly busted. You’re safe to enjoy brown noise without
any additional brown. There are other noise colors, too, with frequencies
that are adjusted in different ways. But white, pink, and brown are the three main
ones. You might find the sounds of white, pink,
and brown noise relaxing, and if you do, you’re not alone. Many people play these sounds to help them
work or sleep, but why? Again, the answer lies in human biology. Your brain is especially attuned to detect
changes in your surroundings if there’s a low level of background information. Like, it’s easy to tell the difference between
two and three people talking at once, compared to ninety-nine versus a hundred people chatting
away. Still just one extra person, but your brain
has a harder time detecting that. When it’s silent, almost any sound can alert
your brain, and you can’t help but pay attention. After all, it might signal danger – a throwback
to our evolutionary ancestors’ worries about predators or other threats. An unfortunate side-effect of that is that
a dripping tap or a snoring partner in a quiet room can lead to some pretty frazzled nerves! But white, pink, and brown noise — playing
across all frequencies — are like muffling blankets of sound. They mask other sounds by making them less
significant compared to the background. So the solution to annoying noises can sometimes
be more noise – sounds that come in many colors! Thanks for watching this episode of SciShow,
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