I think I know where Sig229 is coming from. My aunt's blind, and she can tell you how your other senses become more discriminating when you lose one. To Sig's uncle, he can probably tell just by hearing whether it's the wind or an intruder , whereas you or I might not.
I like the idea, sure there are other practical ways of securing your home and sure they might work, alarm systems are great if they run off batteries, because electricity does go out especially during storms, blizzards or if a SHTF scenario should happen, but then again batteries do fail also after time, whether solar or whatever type they are.
I applaud your Uncles for ingenuity and using a simple device as a possible alert system. Though I have to agree with a couple of other folks that the chance for an accident is upped considerably. I'm sure though he's been doing this for some time and has the scenario down by now.
I'm also sure that he acute hearing (or I hope so at least:wink:) will make him more aware of footsteps and such since he lives alone and thus he will be more cautious then to just go shooting at wind chimes, I'm sure he's more cautious then that.:smile: