My 18 week old female GSD Tess is very vocal but mainly when she's really happy or excited. I was taking her to day care a couple of times a week to try and socialize her and when I would pick her up at the end of the day, she'd be so excited and happy to see me that she'd vocalize all the way home, without stopping! I think of it as her telling me about her day, it makes me laugh to be honest with you. She's also like that in Petco or Petsmart and I chalk it up to being excited. I know how you feel though, it can attract a lot of looks, but for the most part, it makes people smile and they usually come over to say hello to her.
I'm not sure if it's something that will last into adulthood or if it's a puppy thing, only time will tell. I wouldn't be too overly concerned about it right now, if it's in their nature, I don't think there's going to be too much we can do about it.