We did a home defense study in College about a thousand years ago...
In a darkened room: we cycled the actions of various types of firearms.
The ONLY one that was recognized by everyone, and got the most emotional responses: The sound of a 12 gauge being racked
...
#9 shot, and improved cylinder choke (if any!): it'll minimize penetration of walls; yet leave a miscreant leaking from a whole lot of icky places!