A sound that contains every frequency within the range of human hearing in equal amounts.
To many people white noise sounds as if it has more high frequency content, but this is because each successive octave has twice as many frequencies as the one preceding it. Pink noise is similar except that the white noise is filtered to reduce the volume at each octave. This is done to compensate for the increase in the number of frequencies per octave. Each octave is reduced by 6dB, resulting in a noise sound wave that has equal energy at every octave.