PetSafe bark collars with our patented Perfect Bark dual detection technology will not be set off by another dog's bark. The collar "hears" and "feels" the bark of the dog wearing the collar so that it is only activated by the bark from the dog wearing the collar. The unit contains a microphone that hears the bark and vibration detection that feels the vocal cords when the bark is made. If the collar doesn't experience both of these sensations at the same time, the collar won't issue a correction. So multiple dogs can each wear bark collars and you, as a pet owner, don't have to worry about your dogs getting corrected unnecessarily.