If your dog barks incessantly for no particular reason, a bark collar may be able to help you get a little peace and quiet. Some bark collars are electric and may cause harm to your dog, but this spray collar from Petsafe is 100% safe and much more humane than using electric shock.
This video shows the Little Dog Spray Collar, which is suitable for dogs up to 55 pounds. The company also makes a no-bark spray collar for dogs 40 pounds and over. They both work in the same way. The collar registers the vibration of the vocal chords and the audible sound of the bark. When it senses your dog is barking it sprays him with a quick blast of lemon scented spray.
Because the collar uses both audible noise and vibration sensors, there is no risk of it correcting your dog if another dog barks or if the device picks up on other loud noises. Your dog will get consistent correction every time he barks, and you should notice an improvement within a few short days.