Sox, the sire of these pups, is a singer. He likes to howl when our family howls. Once we get him going, he'll sing for a while. He has the sweetest voice. There is NO guarantee your puppy from us will sing.
This puppy started crooning with me right before he left our place with his new family.
For our pups families, just throw your head back and howl for all your worth. A higher pitched voice works better than a lower one. The more mournful you sound, the more likely they will join in. If your puppy is a singer, he'll soon join along. Give it plenty of tries and continue as they grow because some pick it up later.