I have read about tajwid and it only says to enunciate and make clear distinction/pause between each ayat. And yes Allah subhanahu wa ta'ala says to recite in a measured form but does not say anything about the pitch of our voice. Many of those who recite seem to be arbitrarily assigning pitch to words as they go, using an unnatural voice from how they would speak any other true thing. The closest thing I can compare it to is singing. I understand the rhythmic aspects but I do not understand the weird things people insist on doing with the pitch of their voice. It's very confusing and everyone I ask seems to dodge the question, I don't know why. Any one else want to weigh in on this?
Allah knows best.