This is a video demonstration of The SilencerCo's Salvo 12 shotgun suppressor. Apparently it reduces the sound of a shotgun blast to around 137 decibels, or the equivalent of "someone loudly clapping their hands in front of your ears". Which, for the record, will still get you punched in the f***ing face if it's my ears you're clapping in front of.
Keep going for the video.
Thanks to Lanar and Rubbertoe, who agree silenced shotguns are the preferred weapons of the zombie apocalypse because zombies will come running to the sound of gunfire because they're f***ing stupid.