is it healthy for a dog not to bark?

[GeorginaJay]

my grandma just got a new puppy. she's nine months old. she's had her for a little over a week now and she hasn't barked once. she hasnt had a very good life until now. shes been abused for a while. is she scared to bark because of her past maybe? does she have a sickness? is she deaf? wh wont she bark? shes a completely sweet little puppy but she doesnt bark. whats wrong???
she's also a shih tzu