Many people 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.