Professional Ultrasonic Pet Training Whistle Stop Barking Dog Training Tool With Lanyard. Whistles are a useful tool for training your pet; to use (1) Get it to know the whistle by calling him (2) Reinforce his attitude with a treat so you know it's a positive (3) Teach him new tricks by associating him with different whistles; It can be one whistle, two whistles, a continuous whistle, etc.