Listening to pink noise can aid your sleep | Sunday Observer
Science behind sounds

Listening to pink noise can aid your sleep

4 December, 2022

The sound is a gentle roar — a bit like a distant waterfall, or the wind rushing past your car windows on a long drive. It’s continuous, fuzzy and surprisingly soothing.

Welcome to ‘brown noise’ — the latest trend for helping improve your concentration.

While most of us have heard of white noise — that blizzarding static sound that you used to get on TV channels when they were out of service — brown noise consists of lower-frequency, deeper sounds.

It’s wildly popular on social media as a study aid — on apps such as TikTok, videos of people hearing brown noise for the first time have received millions of views.

Adherents gush about profound feelings of peace, while some with ADHD claim it concentrates their thinking more even than medication.

It’s not just brown or white noise; there’s ‘pink’ noise, said to help you fall asleep and sleep longer; and ‘binaural beats’, to help concentration and anxiety.

But while we might be interested in the idea that different sounds could improve our attention, mood and productivity, ‘it is important to find out what the real impact is on the brain’, said Nilli Lavie, a professor of psychology and brain sciences at University College London.

So what is the science behind these sounds — all readily available for free on YouTube — and can they really help us? Professor Lavie offers her verdict while I try them out to see if noise does anything for my concentration.

White noise

This is a familiar sound, a ‘shhh’ similar to a hair dryer. It was identified by engineers back in the 1920s and includes all frequencies audible to the human ear, ie, between 20 Hertz and 20,000 Hertz — a very low organ pipe might produce a 20-Hertz sound, while a dog whistle can be 20,000 Hertz.

This span is why it’s called ‘white’ noise, in a nod to light, which turns white when all the light frequencies are in a single beam.

Prof. Lavie said there are ‘some studies’ showing it improves attention, both for those with ADHD and everyone else, too. ‘And there’s an excellent explanation,’ she said. ‘White noise contains all the frequencies of sound intermixed, so it helps to camouflage peripheral sounds really well. Attention is better focused when there isn’t an attention-capturing distraction — white noise will help to tune those out. There is a compelling case to be made for its efficacy, with a good mechanism behind it.’

Pink noise

Like white noise, pink noise contains all the frequencies detectable to humans. The difference is that the higher frequencies are deliberately toned down, ie quietened.

This should mean that pink noise might be particularly effective for masking higher-frequency noises — for example, the annoyingly shrill beep of a car alarm — because the lower frequency sounds are relatively more intense in the pink noise.

Prof. Lavie said, ‘Pink noise changes the amount of sound energy — simply put, the intensity of the volume — inversely to the frequency. So it makes higher-frequency sounds appear quieter.

‘It’s interesting, although there hasn’t been as much solid research into it as there has with white noise. It may sound more pleasant to some people than white noise due to this dampening of the higher frequencies. And it might be worth trying if you know you specifically want to mask higher-pitched sounds.’

Brown noise

The popularity of brown noise may be recent, but it’s actually named after Robert Brown, a Scottish botanist who, in 1827, discovered ‘Brownian motion’ — the random movement made by pollen grains suspended in water, observed under a microscope.

Brown noise mimics this oscillation, with sound signals that change randomly from one moment to the next, producing an overall impression of static — and supposedly improving concentration. Some users describe it as ‘life-changing’.

Prof. Lavie said, ‘Brown noise is like an exaggerated pink noise. So while pink noise lowers the intensity of high frequencies to make it sound quieter, brown noise does it, too, but in a more extreme way — so the impression that’s left is of only low frequency and bass-heavy notes.’

As a result, the sound is even lower and more rumbly than pink noise. Like pink noise, it will be potentially helpful in screening out high-pitched noises, and some fans argue that it can actually be more effective for falling asleep.

Binaural beats

For these, you need a pair of headphones. That’s because binaural beats are produced when two slightly different sound frequencies are played in each ear, and your brain then splits the difference.

For example, if your right ear is hearing 400 Hertz and your left ear is hearing 410 Hertz, then your binaural beat comes in around 10 Hertz. But this sound only exists in your own brain — it’s an auditory illusion. This — so fans say — is where the magic comes in. Instead of hearing two competing sounds, your brain creates its own sound, which is heard as a rhythmic beat rather than a continuous sound.

“The brain is “tricked” to perceive these as one sound coming from an intermediate location, and the difference in frequency is what creates the perception of beats,” Prof. Lavie said. She said there is some research to suggest that listening to binaural beats may improve attention. “The hypothesis is that this method entrains the brain to produce brain waves at the same frequency as the sound it perceives, and sometimes it seems to work.”

By stimulating particularly beneficial brain waves, binaural beats are supposed to boost cognitive and emotional function — potentially improving memory and attention, reducing anxiety and fostering good sleep.

“This is entirely different from the masking mechanism of white noise,” said Prof. Lavie. “There has been research to measure brain waves while people perform a task that requires focused attention — listening to binaural beats — which did show a brain entrainment effect, but overall, the studies are far from conclusive.” There are also some people who claim binaural beats should be treated with caution, precisely because of their effect on brain waves. Prof. Lavie said, “When you find ways that help you concentrate, it can feel as though you’ve hit the jackpot. Our research shows that people feel happier when they can concentrate.”

- Daily Mail