Spray bark control collars use an unpleasant scent or water to deter excessive barking.
Spray bark control collars have metal sensors which touch the dog's neck and detect vibrations from the dog's vocal cords. When the dog barks, the collar emits either a scented spray like citronella oil (lemongrass) or lemon juice, or just plain water. Dog's find all of these substances to be unpleasant when sprayed on their faces, and they come to connect barking with experiencing these negative sensations.