In need of help, Inconsistent levels in sweep and SPL

[GriffinO]

When using SPL my readings will drop from 80db down to 30db with no changes in position or volume on AVR also when doing sweeps I do a volume check and I get the ok then do a sweep and volume is too low. When I check volume again it is low but after 5 to 7 checks the volume comes back.

 

[John Mulcahy]

Might be some form of noise cancellation processing. If you are on Windows make sure enhancements are not enabled on the audio input properties Advanced page (System - Sound - Related Settings on right hand side - Sound Control Panel - Recording - select UMIK, click Properties button).