What is White Noise?'
White noise is a type of noise that is produced by combining sounds of all different frequencies together. If you took all of the imaginable tones that a human can hear and combined them together, you would have white noise. The adjective "white" is used to describe this type of noise because of the way white light works. White light is light that is made up of all of the different colors (frequencies) of light combined together (a prism or a rainbow separates white light back into its component colors). In the same way, white noise is a combination of all of the different frequencies of sound. You can think of white noise as 20,000 tones all playing at the same time. Because white noise contains all frequencies, it is frequently used to mask other sounds. If you are in a hotel and voices from the room next-door are leaking into your room, you might turn on a fan to drown out the voices. The fan produces a good approximation of white noise. Why does that work? Why does white noise drown out voices? Here is one way to think about it. Let's say two people are talking at the same time. Your brain can normally "pick out" one of the two voices and actually listens to it and understands it. If three people are talking simultaneously, your brain can probably still pick out one voice. However, if 1,000 people are talking simultaneously, there is no way that your brain can pick out one voice. It turns out that 1,000 people talking together sounds a lot like white noise. So when you turn on a fan to create white noise, you are essentially creating a source of 1,000 voices. The voice next-door makes it 1,001 voices, and your brain can't pick it out any more.
What does White Noise sound like?
But what does the white noise sound like? Well, the best description would be to say it sounds like a slow soothing “whoosh.” Many say it is the sound of the rain, or the waves gently caressing the shore, or the wind blowing through the trees. It is a very peaceful sound that is instinctively soothing and calming to the ears and minds of humans of all ages. White noise is actually a sound given to us by Mother Nature, in the same way as she has provided us with water and air.
Noises at levels as low as 40 decibels or as high as 70 decibels can keep us awake. That means that a dripping faucet can steal your sleep, as well as the next door neighbor's blaring stereo. But the absence or presence of a familiar noise can have as great an impact on your sleep as out-of-the-ordinary noises. Studies show that sirens and traffic noise from a city street can actually become soothing to longtime city sleepers (they will cringe at the thought of sleeping in the serene desert or mountain climate) just as the absence of the tick, tick, tick of your favorite clock while you try to sleep at a hotel can become a sleep stealer. What to do: Try to block out unwanted sounds with earplugs or use "white noise" such as a fan, air cleaner or sound conditioner. Take your favorite clock with you when you travel in order to recreate familiar sounds that help you sleep.
White-out the Noise
Our sleeping environment is rarely sound-free. It may be plagued by the chugging and whistles of trains, the roar of planes overhead, the clamber or loud music of neighbors, even the incessant cawing of crows in the early morning. The best solution, of course, is to eliminate the noise, but that's often easier said than done. So instead of trying to eliminate all nighttime noise pollution, try masking the noise with a white-noise machine.
White-noise machines are sound-producing devices. With the push of a button, a white-noise machine makes a soft, whooshing noise that can drown out many of the sudden and unpredictable noises that can disturb sleep. The white noise is easy to get used to and is actually quite soothing. More sophisticated models can produce the sounds of rain, wind, waves or other nature sounds, although these may be too stimulating or distracting for some folks.
Unlike the television or a radio, the noise produced by a white-noise machine does not tend to awaken you from sleep because the volume is constant and the sound itself is unchanging. White-noise machines range in price from $50 to $150 and are available from specialty shops, mail-order catalogs and even some department stores
How hearing works
Your ears are extraordinary organs. They pick up all the sounds around you and then translate this information into a form your brain can understand. One of the most remarkable things about this process is that it is completely mechanical. Your sense of smell, taste and vision all involve chemical reactions, but your hearing system is based solely on physical movement. To understand how your ears hear sound, you first need to understand just what sound is. An object produces sound when it vibrates in matter. This could be a solid, such as earth; a liquid, such as water; or a gas, such as air. Most of the time, we hear sounds traveling through the air in our atmosphere. When something vibrates in the atmosphere, it moves the air particles around it. Those air particles in turn move the air particles around them, carrying the pulse of the vibration through the air.
To see how this works, let's look at a simple vibrating object: a bell. When you hit a bell, the metal vibrates -- flexes in and out. When it flexes out on one side, it pushes on the surrounding air particles on that side. These air particles then collide with the particles in front of them, which collide with the particles in front of them, and so on. This is called compression.
When the bell flexes away, it pulls in on the surrounding air particles. This creates a drop in pressure, which pulls in more surrounding air particles, creating another drop in pressure, which pulls in particles even farther out. This pressure decrease is called rarefaction. In this way, a vibrating object sends a wave of pressure fluctuation through the atmosphere. We hear different sounds from different vibrating objects because of variations in the sound wave frequency. A higher wave frequency simply means that the air pressure fluctuation switches back and forth more quickly. We hear this as a higher pitch. When there are fewer fluctuations in a period of time, the pitch is lower. The level of air pressure in each fluctuation, the wave's amplitude, determines how loud the sound is.