Thanks for the info. I have a question - the reason I was unsure of the filters is because when you change the default "Hanning window" to "rectangular," the graph expands and goes beyond the previous reading on the same scale.

I have 2 cdrs from 2 different guys, supposedly both are duplicates of an original commercial cd, but one is louder than the other. When I Analyze them in Audacity, they both show the same 16 khz cutoff. Obviously at least one of them is fibbing, unless it's possible the retail cd could have this cutoff?