A guard dog would help in identifying threats as well...
My 100lb female German shepherd can wake me up pretty darn easy if somethings up.
If the key-on-a-lightstick method is feasable then do it. If not, then boot the door.
Sgt. of Marines, 3rd Award Expert Rifle, 237/250
1st Award Expert Pistol, 382/400
D Co, 4th CEB, Engineers UP!! OEF 21JUN-20SEP2011