I was going to add a similar remark, that never mind decibels, the best “burglar alarm” is the ch-CHAKK! of racking a shotgun, followed by a long, waiting silence… O yah. Bad Guy will suddenly remember pressing business he has elsewhere.
A friend of mine long ago had an idea I liked: When going on vacation, buy 50-lb blocks of dry ice. (Or 30 lb or whatever size it is.) Maybe a dozen, maybe two. Tote them up and stock your attic with them. To the rafters! Then leave.
Immediately after your departure, the sublimated CO2 will begin pouring down into the house, heavier than air, flooding and filling the interior like a colorless liquid, displacing the normal atmosphere and replacing it. Eventually it will leach out, of course, but meanwhile you need have no fears whatever of any house fire while you're gone… and if someone does break in, he'll never know what hit him. He'll asphyxiate and be unconscious within a minute… and you'll find the body when you get home.
[Even if this scenario doesn't occur, you'll have fumigated your house of all insects and vermin, termites, bedbugs, everything.]