Hi Eric; Not sure what you mean by relative pitch. But I would say that if one can't play "by ear", I think they would have a hard time learning and playing Indian instrumental music. The traditional way of learning is by imitating the notes and "gamak" techniques as shown by the teacher. Improvising would come much later. There is very little written down, and the recent use of sargam notation is not based on what we know as concert pitch.