If your pooch protects his or her outdoor terrain with a chorus of excessive barking, the PetSafe Elite Outdoor Bark Control can teach dogs of all sizes to be silent. Disguised as a birdhouse, this weatherproof device has an internal microphone that picks up the sound of barking, then sends an ultrasonic tone to correct your dogs noisy behavior. The ultrasonic tone is inaudible to most humans but is annoying to dogs. Theyll quickly learn to associate their barking with the unpleasant sound. This anti-barking deterrent can also control your neighbors dogs barking if its within the acre hearing range. Best for smaller outdoor spaces, you add more units for additional coverage and strategically hang them in a tree or place on a solid surface outside. Theres a built-in digital timer, like an alarm clock, which can automatically turn the unit on and off at specific times.