From http://www.firstpr.com.au/dsp/pink-noise/ . . .

For the purposes of this discussion, "power" means the average power or energy contained in a signal over a long period of time.

White noise has the same distribution of power for all frequencies, so there is the same amount of power between 0 and 500 Hz, 500 and 1,000 Hz or 20,000 and 20,500 Hz.

Pink noise has the same distribution of power for each octave, so the power between 0.5 Hz and 1 Hz is the same as between 5,000 Hz and 10,000 Hz.

Since power is proportional to amplitude squared, the energy per Hz will decline at higher frequencies at the rate of about -3dB per octave. To be absolutely precise, the rolloff should be -10dB/decade, which is about 3.0102999 dB/octave.

The distribution of energy in pink noise resembles the distribution of energy in acoustic instruments and voice. The distribution of energy in white noise reproduction asks a high frequency driver to handle a power level similar to that of mid and low frequency drivers – not a good thing unless you keep the overall level low. Either white or pink noise can be used, but pink is going to give a closer approximation of real-world use.

You can find more information on the web using your favorite search engine.


[This message has been edited by bestbang4thebuck (edited October 07, 2004).]