noise generator

trogluddite · 20 Oct 2009

Hi, Look up 'Denormal' in the SM toolbox. Inside the denormal module is a very basic noise generator. The different 'colours' of noise (pink, white, blue etc.) just state how much noise there is at different frequencies - you can get all the other colours by EQing and filtering white noise. The definitions of the different colours all all maths a bit over my head so you'll need to experiment a bit to get just what you want, but I think the code in the noise generator is just generating a stream of psuedo random numbers so it should give you white noise.

The Luddite

MichaelBenjamin · 21 Oct 2009

heres a rough and lightweight brown noise generator from the forum, i dont recall who wrote it, its slightly modified:

streamout bnoise; float cut1=0.99900001; float cut2=0.001; float rand=0.600001; float tmp=0;

rand = rand*3; rand = rand - (rand>2)&1; rand = rand - (rand>1)&1; tmp = rand*2 - 1; bnoise = (bnoise*cut2+tmp*cut1)*0.5; //lowpassfilter & volumescale

for different noise you can adjust the cut rates or apply a whole different filter, also the rand variable could be a streamin.

overhishead · 8 Mar 2010

this is the filter that MDA used to make their pink noise in 'testtone' that hopefully adapts well. after my research, i have determined this filter is best served with oversampling.

polyin in; polyout out; float z0,z1,z2,z3,z4,z5;

z0 = 0.997 * z0 + 0.029591 * in; //pink filter z1 = 0.985 * z1 + 0.032534 * in; z2 = 0.950 * z2 + 0.048056 * in; z3 = 0.850 * z3 + 0.090579 * in; z4 = 0.620 * z4 + 0.108990 * in; z5 = 0.250 * z5 + 0.255784 * in; out = z0 + z1 + z2 + z3 + z4 + z5;

//adapted from MDA TESTTONE's source code (open source)

Dave · 28 Mar 2010

Is the stock noise module "white"?

And how to include the pink noise code above?

philter5 · 28 Mar 2010

Dave wrote: Is the stock noise module "white"?

And how to include the pink noise code above?

yes it´s white (or at least it is supposed to be white). this pink noise code filters pink noise from a white noise. just copy the code into synthmaker and connect a white noise to the input. the output of the code module is then pink noise

trogluddite · 28 Mar 2010

It's worth making one little alteration to the code... Relplace the... polyin in; polyout out; with... streamin in; streamout out; That just makes the code a little more versatile - the polyin/polyout can only be used with polyphonic streams (Synths), whereas the streamin/streamout will autodetect what kind of stream is used, so they'll also work in mono or quad (for FX etc.)