I use a noise cancelling headset daily in my flying job. When I was researching muffs for shooting, I found that the electronic muffs geared towards the shooting sports were not noise cancelling, rather they start to "filter" sound at a preset db threshold. Basic noise reduction wasn't much better than ear plugs. I had some custom ear plugs made that work very well, although the spoken word is slightly muffled.
I called Bose, the maker of our aviation headsets, and asked if they'd work for shooting. The explanation I got was that noise cancelling can't keep up with the spike in noise level that is produced by a firing gun.
Just my two cents.
S