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Re: Digital Distortion

Subject: Re: Digital Distortion
From: Rob Danielson <>
Date: Sun, 29 Jun 2003 13:09:39 -0500
>In a message dated 6/24/2003 12:49:41 PM Pacific Standard Time,
> writes:
>>  I have an opinion on that: never normalize. Never. No need for it. At
>>  the last stage of CD mastering, overall levels might be raised so the
>>  loudest sounds are close to max or limited close to max, but that's
>>  as far as you want to go. In intermediate steps, you need headroom
>>  for processing.
>What about normalizing to 50%. I do this on all my recordings before I sta=
>to edit?. Am I making a mistake? I use CoolEdit.
>John V. Moore Nature Recordings

To me, this raises the question about how much bit depth affects
sound quality and, if so, when is it appropriate to change it.

If a sound is saturated in the field, say above 15%*, I agree with
Dan, no need to normalize just to use the file, you can boost
adequately in the mix or even when burning to CD. If a field
recording has peaks lower than 10%, and I need to equalize it, I go
ahead and bring it up as close as I can to full saturation (90-97%)
at the same time (remembering to bring back speaker playback level).
I don't normalize just to normalize. If I do have to equalize a 15%
saturation file, I do the same because there's always a good chance
I'll be doing some more things to it later on.  If a file uses all
the bits, it withstands and "holds"  alteration better. Most
noticeably, there is less discrepancy in sound quality between
previewing a change like eq and listening to the file after its been
processed. Those working on computers without sound cards might have
observed this.

The only thing risky about 97% saturation is blowing your speakers.
As long as a file has to undergo a change, one may as well grab the
bit depth. If I need max volume and it acquires harshness-- then I
try to address this problem with eq at the same time.  I routinely
mix many sound files all with peaks at 97% or  -.3dB.  As long at I
do not boost any of them, there's no over-modulation or distortion.
When multiple generations are involved, the mixes made from files
with good bit depth stand-up better and seem smoother. True also from
unchanged field recordings. For a while, it made me nervous to see
all those big fat mix files, but they all come down when burning to

I mention this because it seems bit depth could be a bigger factor
for people working without an audio card or a cheap audio card where
the digital to analoq (D->A) is marginal to start with.  Makes sense
that monitoring would be more accurate with more bits to work with.

*These are only ballparkpercentages because it depends on how loud
the particular element will be used in the final sound file or mix.
Rob Danielson
Film Department
University of Wisconsin-Milwaukee


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