Im sitting and listening to the attack dog bark and thought a bigger attention getter,the sound of a pump shotgun being pumped!
The wav file (the sound of the shotgun being pump/loaded) can also be
found here. Then use a motion sensor to trigger the sound to play. There are a bunch of ways to cause the wav file to play. I use [the software]
Bill's Voice Commander (BVC). BVC will not only play the wav file it will also speak the text I give it to speak... and it listens to/for the X10 commands (like a motion sensor) so it knows when to play or speak.
You can also do a similar project using an MP3 player, motion sensor, appliance module, and computer speaker.
My backyard voice warning can be seen in my old YouTube Video here.
http://www.youtube.com/suitmanIM Good luck with your project!
If necessity is the mother of invention.... Boredom might be inventions drunken barfly at closing time.