Thanks for the suggestions. That's the kind of thing I was hoping for. I get the basic idea of what normalizing does but there are so many parameters to adjust. In Soundforge you can select RMS or Peak. From your comment I would use RMS as my target. Am I right in assuming that normalizing the RMS could result in pushing the peaks to clip? I guess this is why there are plug-in chains. Would I use a compressor to tame the peaks and would I do that before or after?
"In Soundforge" - I don't know, I use Adobe Audition and do it separately in 2 ways:
1. after "normal" normalization use compression (you have to set the ratio and the threshold, eg. 6 and -3dB) and then normalization again. You may repeat this process if RMS is not as what you want, but be careful to not overdo...
2. just use Limiter (as a Vst Plug-in) with threshold you want - limiter is dooing likely generally the same as (1) but is written by a "specialist"
A compressor approaches a limiter when the /ratio/ approaches infinity -- that is, the above-threshold slope essentially turns flat. You lose all dynamics for the audio that is above the threshold.
As for applying them.. The sequence I'd suggest is:
Normalize (this puts the peaks at or just below 0.0dB)
Compressor (ratio and threshold adjusted to cover the range you wish to compress)
Normalize (if the compressor doesn't do an automatic or manual post-compression gain boost)
A fairly fast/deep compressor setting would be something like: 6:1 @ -24dB. In the source, a signal at 0.0dB (24dB above threshold) will be reduced to -20dB (24/6 + threshold). -6 => -21dB, -12 => -22dB, -18 => -23dB, -24 => -24dB. You've squeezed the top 24dB of dynamics into a mere 4dB range. You can now apply 20dB of post compression gain to move the peak back to 0.0dB (and audio that was at the -24dB point is now at -4dB, and ALL signal below the threshold has been raised by 20dB).
As stated, that's a fairly heavy compression... 3:1 @ -18dB is probably more common. inf:1 @ -3dB would be a limiter.
I would NOT recommend "redoing" a compressor. Instead, "undo" the first try, change threshold and/or ratio, and try again. In the example of 6:1 @ -3dB, the top 3dB is compressed to take up a range of half a dB... If you then reapply the compressor (assuming renormalized) what had started life as the first 3dB and is now 0.5dB range becomes a 0.08 dB range.