When a dog has a deep relationship with its owner, it will bark to arouse the owner's pity when it is left alone. You can place a small alarm clock or a radio with a low volume under the mat of the kennel. When the owner wants to leave, you can order the dog to return to the kennel, then turn off the lights and close the door to leave. After training several times, the dog will consciously return to the den when the owner turns off the lights, closes the door, etc. The hidden alarm clock and radio sound in the kennel will make the dog calmer. After the dog gets used to it, you can take away the alarm clock and radio.