| white noise |
[25 May 2005|07:59pm] |
1. a signal comprising random noise, providing constant energy at all frequencies, similar to the sound heard when an FM radio is set between stations.
2. A noise whose power spectrum is flat.
What is white noise? Basically, it's random, indistinguishable noise, which you hear in everyday life, but pay little attention to. An electric fan makes white noise. The hum of your refrigerator is white noise. Running water is white noise. Many people talking can be white noise. For instance, if two people are talking at the same time, your brain can normally "pick out" one of the two voices and actually listen to it and understand it. However, if many people are talking simultaneously, there is no way that your brain can pick out one voice. It turns out that many people talking together sounds a lot like white noise.
Because white noise blends into the background of life, it is often used to soothe people to sleep. Fisher Price even makes an aquarium white noise machine for cribs. The noise is not offensive, even though it's comprised of many different frequencies, because the energy level is the same for each one. They blend together into one incoherent sound, making each separate frequency unnoticeable.
You may hear your electric fan when you first turn it on, but your brain quickly loses interest when it can no longer distinguish one unique frequency. Your mind then focuses on individual noises, rather than the hum of so much as a radio no longer tuned in.
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