Why is it...

....that whenever I get set to do a voice-over audition at home, all of a sudden, airplanes fly lower, big trucks go by in a convoy down my street, babies start crying, car alarms go off, my cat goes ballistic, the phone rings, ambulances and fire trucks are called, and basic pandemonium ignites?  Before I turned on the mic, it was as silent as a tomb.  Murphy's Law.