ultrasonic Bark Control: When Your Dog (or Your Neighbors Dog) Starts Barking, The Unit Emits A Safe, But Annoying High-pitched Ultrasonic Tone When The Barking Stops, The Tone Also Stopsuse This Bark Deterrent In Any Season And During All Weather Conditions To Stop Excessive Barking we Help Pets And Their People Live Happy Together ultrasonic Anti-barking Device Is Within Range Of A Barking Dog, An Internal Microphone Picks Up The Sound And The Unit Is Automatically Activated. The Ultrasonic Sound Can Be Heard By Dogs But Is Silent To Humans. outdoor Sonic Bark Silencer Can Be Hung On A Tree, Indoor, Outdoor Wall Or Fence Post To Stop Dogs Barking. Make Sure The Ultrasonic Bark House Be Placed Facing The Dog And Within Range Of The Dog Up To 50 Feet Away. the Ultrasonic Bark Controller Uses High-frequency Sound That Works To Reduce Excessive Bark Of Dogs Within Hearing Range Suitable For Dogs 3 Months And Older Up To 50 Feet Range. Note: If The Dog Is Deaf Or Hearing Impaired, He May Not React To The Bark Control Device.