We have a tool called ACX Check which will tell you the noise level, RMS (volume) and peak sound values. It’s normally used to make sure your sound work meets ACX AudioBook standards.
You need to have at least a half-second of silence in the show for ACX Check to work. I have a suggested sound clip format for testing and posting a sound clip on the forum, but it works on free-form performances, too.
http://www.kozco.com/tech/audacity/TestClip/Record_A_Clip.html
http://wiki.audacityteam.org/wiki/Nyquist_Analyze_Plug-ins#ACX_Check
How to install plugins:
http://manual.audacityteam.org/man/customization.html
There’s also ways to measure audio noise manually, without the extra tool.
Let us know.
Koz