You need to know ACX Check noise analysis depends on finding at least half-second of Room Tone to analyze. If it doesn't find that, the reading will go straight into the toilet.
That may seem a little wacky, but if you read the ACX Submission Specifications, some Room Tone is built in and they will reject a submission without it.
ACX Check is not a generic analysis tool although you can use it like that if you're careful.
It is a collection developed from other tools and techniques. You don't have
to use ACX-Check. I published a page of analysis techniques which will do the same thing—at great expense of time. Get a good strong cup of coffee/tea and comfortable chair......http://www.kozco.com/tech/audacity/ACXT ... sting.html