Bending Study Level 1

Hi David, in the first two video's were you bending using a tongue blocking or lip blocking. I can't seem to understand when tongue blocking how to keep the tongue on the harmonica blocking holes and move the middle of the tongue up and back when also trying to inhale thru the side of your and keeping a good embouchure. VS. lip blocking were the tongue is in the middle and able to move up and back and constrict the throat without much problem. What am I missing or not doing right. Thank you .