Sidebar on PINK NOISE

Pink Noise is an extremely handy audio test signal and it is worth discussing here. Pink Noise is derived from White Noise, which is the audio equivalent of white light. White Noise is random motion in the audio spectrum with equal power at each frequency. Our hearing is exponential, and we hear each octave as “the same amount” or “the same size.” Each octave has twice as many frequencies in it as the one below it. White Noise, with equal power per frequency, therefore has twice the power (3 dB) in each octave than the one just below it because it has twice the number of frequencies. We hear White Noise as “bright” or with the upper octaves emphasized. To make Pink Noise, we filter White Noise with a 3 dB/octave-slope low pass filter, which gives us a signal with equal power in each octave. This makes it extremely useful for audio measurements and our musical concerns. Pink Noise has another advantage as a test signal, compared to a swept sine wave: because it is random and constantly changing, it has the dynamic characteristics of a musical signal. Neat!

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