Hi, I'm new to Dobermans and I've also never had a dog this large before. I have a 5 1/2 month old puppy. He never barked before but he has recently started barking when he hears distinctly the either of my neighbors male voices in their yards or if someone screams next door in the yard. I tell him NO and he stops but I'm not sure if I'm training an important instinct out of him. So when is an appropriate time for him to bark? Is it okay for me to stop him from barking at the neighbors voices and will he still have the instinct to bark when it is important like if there is someone lurking near the house? Thanks!