**This is only my opinion**
Well I know there isn't any permits to discharge a firearm
Also in AZ, you don't need a permit to own or purchase a handgun.
I would imagine if you felt the need to fire a gun in your house, fearing for your life "poisonous snake" It would be legal. It would probably be smart to contact the police.
You should also note the if it's your gun, its your responsibility whether you meant to fire it or not.
I think the best way to get an answer would be to actually call the police and ask them that question.
I have snake shot for my .44, and honestly its not that loud, so there's a good chance no one would hear it. There is also not much penetration at all.
I had a "not so great" experience a few years ago when I accidentally discharged my 1911 in my apartment. Thank god no one heard it, but the bullet went through my mattress, through the wall and was laying on the floor of the next room. I didn't call the police, and no one ever mentioned it, so I got let off easy. My wife was freakin pissed though.
In the end, I put the bullet back in its casing, and tied a lanyard around it and consider it my good luck charm, and remember not to be a lazy dumbass when it comes to live firearms.