in case anyone is tracking this thread, here is another alarm device, looks like it would work better than the watch version, since the sound wouldn't be muffled (if you don't mind hacking, you could probably even integrate this with your HA):
http://www.axbo.com/infactory/1_home_en/news_list.jsp.html
http://www.axbo.com/infactory/1_home_en/news_list.jsp.html