Originally Posted by alpha434
It's basically impossible to measure decibels off of video. Video cameras adjust volume dynamically besides not accurately recording sound in the first place.
To really tell the difference you need a better audio recording rig than what 99% of non-professional video cameras have built in. Would be better to have the camera framed with a decibel meter in the foreground and the shooter in the background so you can see the results since hearing them will be hit or miss with a camera mic.
In fairness though, I could still tell a difference. The "crack" was much less pronounced with the raincover on vs. off.