Undetectable to the Human Ear High-Pitched Screech!
Ultrasonic collars that utilize sound as a deterrent deliver a high-pitched screech that is quite uncomfortable to a dog’s sensitive hearing. This setting is usually adjustable, to minimize the collar’s response to common nearby sounds other than barking. People who dislike shock collars are much more tollerant of Ultrasonic Bark Collars, as they are less harsh. One of the prime disadvantages is that any other dog nearby will also activate Ultrasonic Bark Collars.
Dogs can become conditioned to the sound and learn to ignore!