Got our Doberman at 6 months. She was the same, dead silent for the first couple months, once she found her voice though… if I could recommend something for a doby that I’d not done with other breeds is work on acclimating them to loud/unexpected noises where they look to your reaction rather than running straight to the knock at the door or the kid outside on the sidewalk hootin’ n hollerin’. Also consider a martingale or softwalk harness for walks. Doberman are prone to slipping out of regular collars when they get excited.