What Is White Noise?

This technological wonder helps people sleep, but how does it really work?

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Shhhh. That’s not the sound of the sea, or a co-worker trying to whistle, it’s the relaxing, isolating sound of white noise. The strange phenomenon of listening to the equivalent of active nothingness is more popular today than ever before, and for many people, it’s incredibly relaxing.

But what is white noise, and why do people like listening to it so much?

What Does White Noise Sound Like?

Although white noise might traditionally be characterized by the crackly buzzing that could be heard if you tuned your TV in wrong, technically, white noise is any sound of varying frequency with a consistent power spectral density. In a more practical sense, white noise is any consistent sound your brain will interpret as a solid body of unremarkable sound, rather than individual frequencies.

This is important because white noise’s main purpose is to not be heard. That might sound ridiculous, but many people use it to help them study, to relax, or fall asleep, because it helps them to effectively relax the auditory part of their brain to focus on another task.

So, what does white noise sound like? Nothing, after a while. Colloquially, though, white noise can be anything that’s consistent and sits in the background of your consciousness. For many people, this is something as blanketing as the buzzing TV static we mentioned above. For others, it can be the sound of rain on a rooftop, an oscillating fan, or even the sound of the universe itself -- so called, celestial white noise.

What is White Noise Used For?

As well as relaxing, white noise has also been used in the production of electronic music, often with some measure of filtering to create a different kind of sound altogether.

White noise can also be used for testing audio equipment, or to generate truly random numbers for the purpose of lotteries or certain computer applications. It’s even found some use in tinnitus treatment, helping those with the irritating chronic condition to tune out the distracting noises picked up by their ears.

What About Pink Noise?

White noise is very much a flatline auditorily, but there are other colored variants which differ ever so slightly. For people who use white noise for its various applications, these variants can prove more effective.

Pink noise is one of the most well known and differs from white noise in that its power spectral density is inversely proportional to the frequency of the signal, rather than equal intensity to it. This means the lower frequencies in pink noise are louder than the higher frequencies, which can create a sound that has a deeper feeling to it. Many people find this more comfortable, or natural sounding, than white noise.

Brown noise is another common form of white noise, sometimes called Brownian noise or Red noise. It’s based on Brownian Motion, and achieves an even deeper sound than Pink noise.

What is a White Noise Machine?

A White noise machine is any piece of hardware (or arguably, software) that produces sounds consistent with the colloquial interpretation of white noise. That covers everything from the baby sleep devices that play the sound of running water, to 10-hour YouTube videos featuring background radiation sounds from the cosmos.

There are also a number of white noise apps that can be downloaded from the respective App Store and Google Play Store, which offer quick and easy access to White noise in all of its various colors and configurations.

Is White Noise Harmful?

The short answer is: no. However, as with every health recommendation, there are some caveats. White noise at high volumes (think 100 decibels or higher) has been linked with some damage to the tiny hairs within the human ear and could lead to hearing loss in the future. There is also some suggestion that babies who sleep with white noise on through the night (as opposed to being used merely to help them nod off) could lead to slower development in the auditory portions of their brains.

These are often quite limited studies, though, and in most cases are focused on animals, rather than humans. The best option is to keep white noise volume of any type at a comfortable level, and with a baby or young child, try not to leave it running overnight. After all, letting your kids get used to sleeping through the odd bang you make after bedtime will make your life a lot easier, too.