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From: davet@cbnewsj.att.com (Dave Tutelman)
Newsgroups: rec.music.synth,comp.music,rec.music.makers
Subject: Re: White Noise???????
Summary: another use for pink noise
Message-ID: <1990Dec22.133105.8919@cbnewsj.att.com>
Date: 22 Dec 90 13:31:05 GMT
References: <12263@bsu-cs.bsu.edu> <71303@unix.cis.pitt.edu> <1990Dec17.224535.23225@bilver.uucp>
Followup-To: rec.music.synth
Distribution: usa
Organization: AT&T Bell Labs - Lincroft, NJ
Lines: 35

In article <1990Dec17.224535.23225@bilver.uucp>, alex@bilver.uucp (Alex Matulich) writes:
> 
> Actually, the simplest definition of pink noise is a signal composed of
> all frequencies, weighted in such a way that there is equal energy
> in every octave, rather than equal energy at every frequency in the
> case of white noise.
> 
> Pink noise is generally used for testing audio equipment because it
> won't blow your tweeters at high volume levels like white noise can.

Alex,
Good definition, good example.

Another use I've seen for pink noise in audio systems is in the use
of an equalizer to correct for room acoustics.  Equalizers and
audio spectrum analyzers tend to have their sliders (or display bars)
arranged by octaves (or n-per-octave) rather than absolute frequency,
so pink noise is better matched than white.  In fact, what you want is
to adjust the equalizer so that the spectrum analyzer has all bars the
same height.  This indicates equal power in each fraction-of-an-octave,
which is the same as the pink noise in.

If you used white noise for this exercise, you'd have to match to an
exponential response on the spectrum analyzer, much harder than a
simple "all bars the same height."  You'd also need a spectrum analyzer
capable of accurately measuring and displaying very different powers
simultaneously in different bands.

Dave
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|    Dave Tutelman						|
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