A dog's critical socialization period occurs between 3 and 12 weeks of age. This is the time when their brains are waiting for their environment to tell them what is normal. Dogs that experience a cornucopia of sounds, sights and smells during this period grow up to have the most stable temperaments. Don't wait until your puppy is older for it to hear sirens, lawn mowers, vacuums, slamming doors etc. A downloadable very high sound quality soundtrack