If you have ever fallen asleep in front of a television set that was playing static (the hissing sound at the beginning of the HBO intro) you may have experienced part of the cognitive benefits of listening to ‘white noise.’
White noise is named so as it is the sound of every audible frequency playing at once. Try to search YouTube for ‘white noise’ and let the result play in the background. It may be noise to some, but for others, it has the potential to be a balm: videos of white noise have amassed tens of millions of views online.
Researchers have for decades been studying the cognitive benefits of white noise. In an age of perennial distractions, some types of background noise can be preferable to others, and under the right conditions, this could even help you to focus.
Studies that looked at individuals with attention deficit hyperactivity disorder (ADHD), as well as children with reading disorders, found it beneficial to have them listen to white noise while performing tasks. In adults, the recall ability of those who listened to white noise was found to be superior. And for children with reading disabilities, it improved both reading skills and memory recall.
Hearing through clutter
Scientists are still uncertain about the mechanism through which white noise may deliver all these benefits. Although, when it comes to neuroscience, it is good to remember the words of renowned Harvard neuroscience professor Jeff Lichtman: “If everything there was to understand about the brain was a mile, we have walked only three inches.”
A few principles that are increasingly being studied stand out. One is the principle of ‘stochastic resonance’ (SR) – the idea that a signal can be amplified by the addition of a background noise that includes its same frequencies. To put it simply, it could mean that if you are struggling to hear a voice, the addition of the right amount of white noise (which is a collection of all audible frequencies) may make it stand out more.
White noise improves the signal-to-noise ratio (SNR), which Göran Söderlund, professor at the Western Norway University of Applied Sciences (HVL), explains is a person’s ability to “differentiate between the surrounding noise and the target signal.” His work has demonstrated the cognitive benefits of white noise for both children with ADHD as well as those with reading disabilities. But the exact mechanism for why this works is not fully understood, he tells Happiest Health, though he believes SR plays a role.
The dopamine factor
The second factor is that the ability to discern SNR may be regulated by tonic dopamine levels, Söderlund explains. And here too, white noise may play a role, even though animal studies have shown that white noise by itself cannot boost dopamine levels.
One study found that white noise could adversely affect the performance of ‘super-attentive’ children whilst doing nothing for ‘normal’ kids, but it still benefitted those who were ‘sub-attentive’ before the study.
ADHD can be explained as a dopamine-deficit condition, with low levels of the ‘reward’ neurotransmitter being associated with low motivation, as well as with other comorbidities. Youths with ADHD are 5.5 times more likely to be diagnosed with major depressive disorder than others.
Benefits for productivity and sleep
Moreover, sensory overwhelm is a common ailment for those with ADHD and a little noise can help block out the sounds of co-workers and other distractors. A study published in the journal Noise & Health found that the spectral content — ie the colour — of noise was a factor in worker productivity.
White noise may seem harsh to some but for others, it might promote sleep. Ambient noise generators promising to improve sleep quality have thronged markets, and many apps exist that do the same.
Mind the limit
But is it safe? Söderlund says that such sounds cannot hurt you if listened to them below the recommended level of 75-80 decibels. But with studies finding mixed results in use on healthy participants, it is clear that listening to noise is not everybody’s cup of tea.
While millions treat themselves to a symphony of noisy frequencies — a trend made evident by the white, brown and pink noise playlists on YouTube — the scientific verdict is not yet out.
Not yet a therapy
Urvakhsh Mehta, additional professor of psychiatry, at the National Institute of Mental Health and Neurosciences, Bengaluru, says the advancement of knowledge is still not sufficient to be translated to patient benefits. White noise joins a couple of dozen other potential treatments promising to improve cognition, he adds, noting that a similar approach is present in transcranial random noise stimulation (TRNS).
“Given the novelty of these approaches, the paucity of high-quality research and the multiplicity of contributory factors to cognition, these treatments still are potential treatments that need to undergo the test of rigorous scientific scrutiny,” he says.
“A more challenging and clinically relevant question to be asked in the future would be if there are specific patterns of brain signals that can be identified which are predictive of a good response to white noise. Another question would be, does white noise exposure have any long-term sequelae (effects) that are undesirable?” he asks.
Söderlund, who has been studying these noises and their impact on cognition for decades now, says that while there is ‘loads of work’ to be done, there is a shortage of money flowing into research. “At the moment we’re working on a study on visual white pixel noise on ADHD – and of course, we want to establish the mechanism behind noise benefit. This is, however, expensive.”