What is White Noise?

Many people (myself included) enjoy falling asleep to the soothing hum of white noise, which consists of low-, medium-, and high-frequency sounds played together at the same intensity level. White noise effectively masks other sounds, making it helpful for people who live in loud neighborhoods. That said, there are a few common misconceptions about what constitutes white noise and how it can help you sleep.

What Is White Noise?

When measuring sound waves, “frequency” refers to how fast the waves vibrate per second while “amplitude” (or “power”) refers to the size of the waves. Frequency is measured in hertz and amplitude is usually measured in decibels. The relationship between the frequency and amplitude of a sound wave is used to define different “colors” of noise, which share structural properties with corresponding light waves of the same name.

To produce white noise, every frequency the human ear can hear is played in a random order at the same amplitude. This results in a “shh” sound many associate with television or radio static. Just as white light is thought to be composed of every visible wavelength on the color spectrum, white noise consists of every audible frequency. Fittingly, “black noise” refers to the literal sound of silence.

Disruptive sounds such as a slamming door do not necessarily wake you up because they are loud. Rather, the change in sound consistency from soft to loud can be strong enough to interrupt your sleep. True white noise essentially creates a blanket of sound that masks these sudden consistency changes. And since white noise is audible, it can also be useful for people who do not like sleeping in a completely silent environment.

White noise has proven particularly effective for hospital patients. These settings tend to be quite loud and filled with ambient noise that can disrupt sleep. Studies suggest a white noise machine can reduce sleep onset for patients, or the time it takes to fall asleep, by nearly 40% compared to patients who don’t use these devices. Some studies have also found that white noise can help babies and young children fall asleep more quickly. White noise has also proven effective at helping inattentive children concentrate better in their classrooms.

Pink Noise vs. White Noise

Some people equate white noise to certain ambient sounds, such as a whirring fan or air conditioner, but they are technically not the same. The effect on your ears may be similar, but by definition, white noise must consist of all audible frequencies played randomly at the same amplitude.

Some sounds confused with white noise are actually different colors of noise. A common example is pink noise. While white noise is defined by equal amplitude across all frequencies, the amplitude of pink noise decreases by half every time the frequency doubles. The result is a blend of more intense low-frequency tones and softer high-frequency tones.

The human ear is particularly sensitive to high frequencies, so many people find pink noise more pleasant than white noise. Pink noise may have other sleep benefits, too. Some studies suggest pink noise can actually reduce your brain wave activity. Your brain becomes less active during the initial stages of your sleep cycle. By assisting with this process, pink noise can decrease sleep onset, extend sleep duration, and improve overall sleep quality.

Those who prefer pink noise may also find red noise soothing. Red noise also decreases in intensity as it increases in frequency, but to a more dramatic extent. This produces a low rumbling sound. Alternatively, blue noise increases in intensity as the frequency rises, resulting in more emphasis on high tones and less for low tones. Blue noise can be likened to a fine spray of water.

The best color of noise for sleep will come down to personal preference, If you find high-frequency sounds too harsh, then bass-heavy pink or red noise may be smoother to your ears. If you would rather listen to higher-frequency sounds, white or blue noise might be your best option. We recommend experimenting with different colors using a sound machine that can replicate these noises.

Choosing a White Noise Machine

A white noise machine, also known as a sound machine, can help you create a more relaxing bedroom environment that promotes healthy, high-quality sleep. In addition to white noise and other noise colors, these devices often produce ambient and natural sounds such as chirping birds and crashing waves. Before choosing a machine, here are a few factors to consider:

  • Price: Most white noise machines cost less than $100. Higher-end models typically offer a wider selection of noises and sounds.
  • Size: Sound machines are generally lightweight and compact, though some are exceptionally small and designed for travel.
  • Sleep Timer: Some sound machines have programmable timers that will automatically shut off the device after a certain amount of time.
  • Looping: Some white noise machines loop their sounds at the end and beginning to create a continuous listening experience, while others will stop when the recording is finished.
  • Alarm: Sound machines often feature a built-in alarm to help you wake up at certain times.

This is the exact same white noise machine I use and highly recommend: White Noise Machine

If you’d rather not purchase a dedicated sound machine, you can download a white noise app to your smartphone or tablet device instead. These apps are typically very inexpensive, if not free of charge.