It is a neat combination between design and practicality. We have three different types of collars -
1) Most of the collars are air-activated, so that they will “answer” only when your doggy barks. There is an air-pressure sensor located on the back, which “catches” the air flow created in the neck area, when a doggy barks and triggers the device. Thus, external noises will not trigger them.
2) The mini bark collars are vibration-activated. They react to the throat vibration, when a dog barks. Thus, external noises will not trigger them, as well :)
3) The remote collars are being triggered with the remote control (quite self-explanatory really :))