From batzman@apanix.apana.org.au Wed Jan 18 12:54:48 1995
Date: Thu, 19 Jan 1995 03:01:49 +1030 (CST)
From: Batz Goodfortune <batzman@apanix.apana.org.au>
To: analogue@magnus.acs.ohio-state.edu
Subject: NOISE Three colours to choose from.

Y-Ellow all.
	For all those who wondered what in heck "Brown Noise" was. . .  
This is a description of three different noise colours by David Johnson who 
authers "COOL EDIT". IMHO the best sample editing software in the world. 

Brown Noise has a spectral frequency of 1/2^f. Which means in English that 
there is much more low-end, low-frequency companents to the noise, which
results in thunder and watterfall like sounds. Brown noise is called that
because when viewed the wave follows a Brownian motion curve. That is the
next sample in the waveform is equal to the previous sample plus a small
random amount. This gives the appearance of a mountain range when graphed. 
The wave pattern is very predictable.

Pink Noise has a spectral frequency of 1/f and is found mostly in nature. 
It is the most natural sounding of the noises. By equalizing the rainfall, 
waterfalls, wind, rushing river and other natural sounds can be generated.
Pink noise is exactly between brown and white noise (This is why
some people used to call it tan noise, but pink was more appealing) It is
neither random nor predictable. It has a fractal like nature when viewed.
When zoomed in, the pattern looks identical to when zoomed out, except at a 
lower amplitude. 

White noise has a specttral frequency of 1. In other words, equal
proportions of all frequencies are present. because the human 
ear is more succeptable to high freaquencies, is sounds very "hissy". White
noise is generated by choosing random values for each sample.

Batz 




From jhusted@halcyon.com Wed Jan 18 16:47:11 1995
Date: Wed, 18 Jan 1995 12:39:05 -0800 (PST)
From: James Husted <jhusted@halcyon.com>
To: Batz Goodfortune <batzman@apanix.apana.org.au>
Cc: analogue@magnus.acs.ohio-state.edu
Subject: Re: NOISE Three colours to choose from.

On Thu, 19 Jan 1995, Batz Goodfortune wrote:

> 
> Pink Noise has a spectral frequency of 1/f and is found mostly in nature. 
> It is the most natural sounding of the noises. By equalizing the rainfall, 
> waterfalls, wind, rushing river and other natural sounds can be generated.
> Pink noise is exactly between brown and white noise (This is why
> some people used to call it tan noise, but pink was more appealing) It is
> neither random nor predictable. It has a fractal like nature when viewed.
> When zoomed in, the pattern looks identical to when zoomed out, except at a 
> lower amplitude. 
> 
> White noise has a specttral frequency of 1. In other words, equal
> proportions of all frequencies are present. because the human 
> ear is more succeptable to high freaquencies, is sounds very "hissy". White
> noise is generated by choosing random values for each sample.
> 
> Batz 

Another way of saying this is Pink noise has equal energy per octave and 
White has equal per frequency. If you record on a varible speed tape 
deck, White noise on one track and pink noise on the other, then change 
the speed an octave, one track will sound the same and the other will 
change `pitch'. Guess which one before trying. This is also a good test 
for the quality of your noise generator.

James Husted
jhusted@halcyon.com
