The impact of noise on our wellbeing is undeniable. Noise can disrupt your focus, hinder your sleep and drastically affect your mood. But did you know that different colours correspond to different kinds and frequencies of noise? Every kind of noise has a distinct spectral distribution, and you can use many types of noise to improve your life.
What is coloured noise?
The colour of a noise describes its power spectrum: its strength and frequency. Sound comes at us in waves: tight, short waves (high frequency), long, loping waves (low frequency), or anywhere in between. White noise is the most well-known of all noises and contains equal intensity across all frequencies.
Each colour of noise emphasises certain frequencies, creating a distinctive sound. For example, blue noise has a high frequency and sounds like a hiss, whereas brown noise has a lower frequency with a deeper sound.
“Different colours of noise emphasise different frequencies over others. They have energy in different parts of the sound spectrum,” says Barbara Shinn-Cunningham, director of the Neuroscience Institute at Carnegie Mellon University. “They all have a quality that’s boring to the brain and makes other sounds less perceptible. The main effect is to drown out unexpected or disruptive sounds that would distract you or compromise your attention.”
What is auditory masking?
Auditory masking or sound therapy is a phenomenon in which the perception of one sound, known as the target signal, is affected by the presence of another sound, called the masking noise. The masking noise interferes with the ability of our auditory system to detect specific frequencies of the target signal. Auditory masking is a technique commonly used to help manage tinnitus symptoms.
Sound therapy can make the perception of a particular sound less noticeable or unnoticeable. It is prevalent in various areas such as engineering and psychoacoustics.
Although there is more research supporting the use of some noise colours than others, there’s growing interest in the entire spectrum. Research is focusing on how listening to different colour sounds could help you feel, focus and sleep better at home. Here’s a look at how different noise colours compare.
Different kinds of coloured noises
Coloured noises can be categorised based on the specific distribution of their energy across the frequency spectrum. Some of the most common colours are white, pink, brown, blue and violet, each with a different purpose.
White noise characteristically has equal energy across all frequencies on the spectrum and has a continuous and constant rhythm similar to the sound of static. It is often used to improve concentration as it can significantly drown out or reduce the effect of other noises.
“White noise is especially good for blocking out other irregular and unpredictable noises, such as your upstairs neighbours or phones ringing nearby,” says Alicia Walf, a neuroscientist and senior lecturer at Rensselaer Polytechnic Institute in New York.
Some studies have studied the effect of white noise on humans, and compelling evidence states that it can reduce symptoms of ADHD in children. White noise is also said to help newborns relax and cry less, according to a 2018 study.
Similar to white noise, pink noise includes all the audible frequencies, but it emphasises lower frequencies more than higher ones, giving it a distinct balanced and soothing quality.
While white noise has equal energy across all frequencies, making it sound like static, pink noise has equal energy per octave. In simpler terms, pink noise sounds more balanced because it has more low-frequency components, making it resemble a steady, soothing hum. People often use pink noise for relaxation, sleep, or to drown out other background sounds, just like they might use white noise.
Incorporating a steady source of pink noise during sleep may enhance sleep quality, reduce brain wave complexity and improve memory consolidation.
Pink noise has a more balanced auditory experience and studies claim that it can improve concentration as it aligns well with brainwave patterns. Plus, “Pink noise has been shown to improve memory retention in older people,” says Dr Walf.
The spectrum distribution of pink noise bears a striking resemblance to several sounds found in nature, such as ocean waves and the human heartbeat.
Red or brown noise
Brown noise, sometimes referred to as red noise, typically has a lower pitch and intensity compared to white or pink noise. Its deep and consistent sound makes it effective for masking undesired noises. “It’s similar to the sound conditioners therapists use in waiting rooms. It’s unobtrusive. People find brown noise pleasant,” says Mack Hagood, an associate professor of media and communication at Miami University in Ohio.
Brown noise is a ‘natural noise’ as it sounds similar to steady rain, distant thunder or a waterfall.
More scientific research on the advantages of brown noise is necessary. However, there are indications of its potential benefits. A 2017 study found that listening to brown noise reduced disruptions to workers’ concentration in an open plan office. Additionally, some research suggests that exposure to brown noise may facilitate the transition into REM sleep for certain individuals.
Blue noise has a high-pitched hissing sound similar to steam escaping from a pipe. Many people do not find this noise pleasant, and it is not commonly found in natural settings.
Unlike white noise, which has equal energy at all frequencies, blue noise has higher intensity at higher frequencies and has a much sharper sound.
How to use different coloured noise
Figuring out which colours affect you in the desired ways requires a bit of trial and error, experts say. “Different people react differently to these sounds because they’re more or less susceptible to distractions and more or less sensitive to sound variations,” Dr Shinn-Cunningham says. “Any frequency of noise can be helpful if it helps you focus in on things or ignore sounds that are distracting.”
Try out different colour noises at home to discover which ones aid concentration or relaxation. You can explore colour-noise playlists on platforms such as YouTube or Spotify, download an app or invest in a sound machine that produces a variety of these coloured sounds.
Do you use a sound machine or different coloured noises in your day to day life? Why not share your thoughts in the comments section below?