Hihi
Do you know in what kind of situation they said it? Because "jah" sounds like "ja", which means "yes", and unless I am really annoyed, I wouldn't say it like that. But for example if you're a teenager, and your mother would tell you to come down to eat, and you were in the middle of something you concidered important, then you probably would say it like that, but normally "ja" is pronouced really fast.