The dog whistle has adjustable pitch for active control of the frequency produced. When you blow on the whistle, you can hear the secondary sound made by the air forced through the metal tubing. Adjust the pitch & blow the whistle to your dog. Your whistle has a nut and screw that adjust the frequency when turned. Continue testing until your dog perks up. You will then know you have reached a frequency he can hear. Use the dog whistle with varying sequences to train your dog. The dog's behavior according to your instruction need to be trained. Such as, at meal time, blow on the whistle before they get the food. It will only take a few times of doing this and your dog will react quickly.