In terms of physics the sound (noise) represents wave fluctuation which is capable to extend in the air environment. Color of noise — a spectral characteristic of some types of sound signals which have the physical properties similar to properties of light radiation.
White noise is sound vibrations which spectral characteristic has uniform distribution on all frequency range. This term has analogy to white color. From the scientific point of view in the nature there is no radiation of white color. And actually white color represents a combination of all flowers of a visible range (so-called seven colors of the rainbow). The same can be told and about white noise — it is a combination of sounds of different frequency ranges.
Under category of white noise it is accepted to refer any noise which spectral density is close or identical in some considered frequency range.
White noise in the nature and life
Noise, unlimited on frequency range, is possible only in the theory as it has to have infinite power. However the power of a sound is final size. Therefore in practice the white noise meets only in a limited strip of frequencies. But this strip can have rather wide range. Thus, some sounds can be carried to white noise conditionally. Classical examples of white noise are the sound of waves, a heavy rain and a rustle of foliage on wind, also here it is possible to refer noise of close located falls. And the sound of the remote falls is low-frequency therefore its range is close to pink noise. Also a sound which is close to white noise publish many household appliances: drills, vacuum cleaners, mixers, etc.
White noise in sound recording
Sound producers quite often face such task as cleaning of an audio recording of extraneous noises (hindrances). Specialized computer programs and the studio equipment are for this purpose used. To remove a sound hindrance, it is necessary to determine its frequencies and then to remove these frequencies from record. The greatest complexity is represented by removal of the hindrances spectrally close to white noise. It occurs because during removal of extraneous noises parasitic frequencies "are kind of cut out" from record. But when the range of hindrances is too extensive and distributed in big frequency range, during removal of hindrances also the useful signal, that is sound recording is removed. It is possible to give dictation record of phone call in the bathroom at the switched-on crane or soul as an example. The sound of the flowing water on the characteristics is close to white noise. Therefore if completely to remove it from record, then at the same time also the human voice which will get to the same range, as water noise will be removed, however its range will be several times less.