What Is White Noise and How Does It Help You Sleep?

• Noise is defined as a sound element that occurs within the frequency range of 16 Hz to 20 kHz.
• Among the various forms of noise, white noise is the most well‑known, and it can be further divided into several subtypes.

What is noise?

When we talk about noise, we’re referring to a type of sound element. A wide range of sounds can be classified as noise, especially those that are subtle or barely audible at first. Examples include the faint hum of electrical wiring or the buzz from a coil. Even the slight scraping sound from a dusty or uneven CD can be considered noise.

What types of noise are there?

Just as light can vary in colour, with some appearing warm, and others cool, sound too can be described using colour analogies. “Coloured” sounds correspond to different frequency ranges, with each type of noise occupying its own position within the spectrum.Human hearing can typically detect sound frequencies ranging from 16 Hz to 20 kHz.

Within this range lies white noise, which spans both the lowest and highest audible frequencies. Because it distributes energy evenly across this entire spectrum, white noise can soften or mask sharp sounds, allowing the brain to pay them less attention.

White noise in detail

Historically, white noise was often viewed as a disruptive factor and a meaningless background hiss. Yet modern research suggests it may, in fact, increase cognitive performance in certain individuals. White noise is defined as sound that contains all audible frequencies distributed equally across the spectrum. This wide coverage is why it’s sometimes referred to as broadband noise. In practical terms, you can think of white noise as the static interference from an untuned radio or television, though for some readers, that sound may now feel like a distant memory.

Variations of white noise

In nature and science, we encounter not only white noise, but also blue, violet, brown, pink and grey noise. As their names suggest, these are all variations or “colours” of white noise. Each extends across the audible frequency range, but what differentiates them is the proportion of energy distributed across various parts of the sound spectrum.

In nature, we find sounds such as the rumbling of the ocean or strong wind. These sounds belong to the brown noise spectrum, which occurs at lower sound frequencies, i.e., deeper ones. Brown noise is also characterised by a buzzing quality and is often used for meditation, focus and relaxation.

Just above the range of brown noise lies pink noise, another lower‑frequency variation of white noise. Examples include the sound of flowing water, heavy rain, or the rustling of leaves in the wind. Pink noise tends to sound softer and less sharp than white noise, making it pleasant and calming to listen to.

At the other end of the spectrum are blue and violet noise, which contain more energy at higher frequencies. These sounds are sharper, more piercing, and resemble a hiss or the loud, rhythmic sound of cicadas. 

The last type is grey noise, which differs quite significantly from the previous variations. It contains frequencies from both the lower and upper ends of the audible range, balanced according to how the human ear perceives sound. The result is a neutral, evenly distributed sound that cannot easily be compared to any single natural source.

Beneficial effects of white noise

1. Over many years, scientists have explored the effects of white noise on humans, with numerous studies suggesting potential benefits, though findings are not always consistent. Research indicates possible improvements in work performance, sleep quality (though some studies show no or even negative effects), and symptom management for conditions such as attention deficit and hyperactivity.
2. Other studies, particularly those involving children, have found that white noise may increase cognitive performance in typically developing schoolchildren rated by teachers as inattentive. Conversely, it may worsen performance in children rated as highly attentive.
3. A similar study by G. Söderlund again confirmed that white noise improves concentration in people with language problems and in individuals with learning‑related difficulties. However, it is worth noting that white noise does not benefit all aspects of cognitive performance comprehensively. The opposite effect was found in research by Herweg and Bunzeck, who discovered that white noise selectively impairs working memory when presented during the maintenance phase of a task, compared to performance in complete silence or when listening to a pure tone signal.
4. In contrast, in tasks focused on long‑term memory, it was found that white noise facilitated the speed of perceptual judgments during encoding, but had no impact on subsequent recognition memory performance, i.e., the final state.

The latest findings on the effects of white noise

Until recently, most research concluded that listening to white noise during tasks requiring concentration was primarily beneficial for individuals diagnosed with ADHD or speech disorders, while for healthy individuals, it tended to act as a distraction rather than an aid.

However, in 2022, a groundbreaking study by Awad et al. challenged this understanding. The researchers examined the effects of two white noise levels—45 dB and 65 dB—on cognitive performance, creativity and stress in young adults in quiet, private spaces. The study showed that a white noise level of 45 dB led to better cognitive performance in terms of sustained attention, accuracy and speed of performance, as well as increased creativity and lower stress levels.

On the other hand, noise at a level of 65 dB led to improved working memory, but higher stress levels. This means that different tasks may require different levels of “noise” for optimal performance.

Practical uses of white noise

In everyday life, the most common and practical use of white noise is as a sleep aid to help people fall asleep more easily. Preferences, of course, vary from person to person. Some people prefer complete silence when falling asleep, while others need to hear at least some background sound, such as the  TV. However, using devices like televisions or radios for background noise is not ideal, as their volume and tone fluctuate, which can actually disturb sleep. White noise, by contrast, provides a steady, unchanging sound that helps block out external disturbances, supporting both falling asleep and staying asleep.

Bottom line

When we talk about noise, we are referring to a broad range of sounds occurring within the frequency range of 16 Hz to 20 kHz.

Among these, the most fundamental type is white noise, which is then further divided into blue and violet, grey, pink and brown noise. Noise has beneficial effects on the human body, including: easier falling asleep, improved cognitive performance and reduced stress.