Open Mouth Breathing: For your open mouth breathing, the goal is to inhale through the nose, and open mouth exhale using your belly to push the air out. The goal is to feel all the air come out as you exhale. (This is often to release heat and energy from your body during yoga.)
Closed Mouth Breathing: For closed mouth breathing - inhale through your nose, keeping your lips sealed, constrict muscles in the back of your throat and then exhale back out through your nose. You are going to hear an almost oceanic sound as you exhale through your nose. (This is often done during warm up to build heat in your body). With both open and closed mouth breathing, we want to match the inhale and exhale duration. Meaning if we inhale for a count of 3 seconds, our goal should be to exhale for 3 seconds. 3 Seconds is typically a good start, especially for beginners!