White Noise Machines
refers to a class of appliances that are usually employed to block out or mask annoying sounds in our environment such as that created by neighbors arguing, playing their TV at too high a volume or just the general bustle of activity in a city that can create annoying and distracting noises. These noises in your environment can sometimes be blocked out by using a white noise machine to overwhelm the offending noise with a more pleasant sound of your own choosing. The white noise sound generated by these machines usually consists of all sound frequencies occurring at the same time. This white noise will sound kind of like wind, rain, ocean or a mechanical sound like that produced by a motor or fan. The effect of this jumble of sound waves is that some sound waves get canceled and others get obscured, making the offending sound indistinct and therefore less obtrusive.
Sometimes the problem isn't too much noise but near total silence. Sometimes it is just too quiet which in some people can result in difficulty falling asleep. You have probably seen this phenomenon in action by noticing how a baby can have trouble falling asleep if it is really quiet but if a fan, vacuum or car motor is running, the baby falls asleep easily. It is generally best to play your sound machine at the lowest volume possible; save the higher volume for really loud noises that you can't remedy any other way. By playing a soft sound from a white noise machine, you can give your mind something unobtrusive to focus on and this can result in deeper relaxation and quicker sleep.