[PD] brown/grey noise in pd

Matt Barber brbrofsvl at gmail.com
Sat Nov 14 20:17:32 CET 2015

```"True" pink noise is likewise impossible: if it's equal energy per octave,
then since there is no "lowest octave," any energy in any octave implies
infinity at 0hz. The fexpr~ approach I gave accumulates, but imagines a
"container" with "walls" at +/- 1.0 where whatever was doing the random
walk "bounces" off the wall. It should have a color within auditory range
similar to unrestricted integration. A lot depends on what you want to do
with the noise (it's not necessarily an audio source).

Convolution is a pretty good way to go. I've seen a number of filters that
try to distribute phase randomly across the frequency magnitude curve. Also
remember that the 6dB dropoff is with respect to log frequency, whereas FFT
is linear in frequency.

On Sat, Nov 14, 2015 at 1:35 PM, Martin Peach <chakekatzil at gmail.com> wrote:

> There's [rojo~] in mrpeach, if by brown noise you mean red noise.
> (brownian noise?)
> [rojo~] tends to grow out of bounds, which is a problem with correlated
> noise: if you want long term correlations you have to be ready for the
> noise to get very loud. So in practice there is no red noise possible, it's
> all high pass filtered.
> To get any arbitrary shape of noise it can be done most efficiently by
> convolving a frequency curve table with white noise. The table would have
> the same length as the number of bins in the FFT.
>
> Martin
>
> On Fri, Nov 13, 2015 at 10:35 PM, Alexandre Torres Porres <
> porres at gmail.com> wrote:
>
>> hi, wondering how to implement brown noise in Pd (vanilla or extended) -
>> moreover, I'd like and if there's an external that does it.
>>
>>
>> thanks
>>
>> alex
>>
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