[sdiy] converting white noise to pink noise

Andre Majorel aym-htnys at teaser.fr
Tue Mar 4 23:34:00 CET 2008


On 2008-03-04 13:40 -0500, Amos wrote:
> On Tue, Mar 4, 2008 at 9:05 AM, John Mahoney <jmahoney at gate.net> wrote:
> >  Aaaargh, it's the dreaded MM5837, again! Ah, well, it's fine for
> >  testing purposes, it's just no good for making music.
> 
> I assume it's an LFSR with a very short word length?  Seems like a
> modern micro with long words could implement a simple LFSR that sounds
> fine.

But note that long period does not imply good sound. For example,
http://www.maxim-ic.com/appnotes.cfm?appnote_number=1743&CMP=WP-9
is a 32-bit LFSR with a 2**32 period that does not sound very
white.

> Question is, is there an algorithm that would actually weight
> the "noise" at the time of generation, to give pink noise
> output?  Or is it better to make the whitest noise possible and
> use a passive filter?

y = yprev + rand has more LF energy than y = rand (i.e. white
noise). But I don't think that's pink distribution, otherwise
people would use that !

-- 
André Majorel <URL:http://www.teaser.fr/~amajorel/>
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