Activating a prop by sound

[MMayberry]

I'm trying to help out a fellow haunter who is looking to activate a fog machine with a sound-based trigger.  The trigger would need to hold itself closed or trip a relay to close for a period of time to allow the fogger to do it's thing.  I won't get into fog machine non-operative heating cycles.  Anyone out there with experience tripping props with a sound-based trigger?  ???

[JackMan]

Have a look at these.
http://www.electronickits.com/kit/complete/elec/k126.htm
http://www.electronickits.com/kit/complete/elec/UK257.htm
http://www.electronickits.com/kit/complete/elec/ck1607.htm

[MMayberry]

Exactly what's needed, and the store is only 30 minutes away.  Thanks JackMan