Manny- I am working some expanding intervals. P. 127 in Arban's, to be specific. I notice tthat when I begin to approach and pass a 6th, my head begins to bob up and down (pivot), especially as I increase tempo. I am almost positive that this is why my low register is not as clear as I'd like. (I also suspect it is keeping my accuracy from being what it should be). Any tips to alleviate this?