A real-time analyzer can be set so that a pink noise input produces a straight horizontal line on its display. With pink noise input, the equalizer is then adjusted to get a straight line output. The sound system is then equalized to the room. For processes of testing and equalizing rooms and auditoriums, it is convenient to have broad-band noise signals. Typically, white noise or pink noise is used.
White noise is noise whose amplitude is constant throughout the audible frequency range.
It is fairly easy to produce white noise - it is often produced by a random noise generator in which all frequencies are equally probable. The sound of white noise is similar to the sound of steam escaping from an overheated radiator. The ear is aware of a lot of high frequency sound in white noise since the ear is more sensitive to high frequencies. Since each successive octave of frequency will have twice as many Hz in its range, the power in white noise will increase by a factor of two for each octave band. Twice the power corresponds to a 3 decibel increase, so white noise is said to increase 3 dB per octave in power.