Does mixing brown noise and white noise create pink noise? What happens if you take a white noise generator, run it through a one-pole LPF set to a low cutoff frequency, and then mix the two together? Do you get pink noise?

Say you have this code:



float noise = noiseGenerator();
float pinkNoise = pinkingFilter(noise); //3dB/oct filter
float brownNoise = onePoleLPF(noise); //6dB/oct filter


Would then pinkNoise roughly equal a mix of noise and brownNoise?

Or going further, can you get intermediate colors by just mixing the three noise signals in varying amounts? Like could a mix between pinkNoise and brownNoise create a 4.5dB/oct slope noise?
Does mixing brown noise and white noise create pink noise?


No. 

Pink noise has a spectrum of that falls with 3dB/octave (or 10dB/decade). The spectrum of the sum of white and brown noise will be "brown" at low frequencies and "white" at high frequencies. The spectrum will have two slopes: below the transition frequency it will be -6dB/octave and above it, it will just be flat.

Somewhere in the transition region will be a frequency range that could be considered approximately  "pink" but it's not really a constant slope.

That transition frequency is simply a function of the mix ratio (and the initial energies) of the two noise signals.

If you define "mixing" as a multiplication and not a summation, the result will just be white.