At first you may need to make the sounds really loud, sort of as a kind of physical exaggeration, in order to understand what they do to the body system - so you need a private place where you can shout really loud. Place your hands firmly on your abdomen for feedback, and go to it. Try doing each one five or six times, that is, a series of "heng" first, then a series of "ha", without any preconceptions, and see what you feel.
"Heng", pronounced "huuuung !", is the easiest one to get; it serves several main functions:
- It simultaneously expands the abdominal cavity outward, forward and downward, reinforcing your "root"; 2) it causes the diaphragm to drop down, compressing the abdominal cavity;
- it causes the epiglottal fold to seal the breath in the lungs and throat, adding "backpressure" to reinforce the body's structure; it is most often used to reinforce an "issue", either a push or a strike.
When someone grunts while performing hard work, they do something similar - it's not an "exhale", because that would reduce the internal pressure, and weaken the body's support structure; a little air does escape, making the audible grunting sound, but then the epiglottis flips down and seals the rest of the air in the lungs, adding pneumatic reinforcement to the body system, and consolidating your whole-body "power".
It's also similar to Jhalandara bandha, as used in advanced yoga practice. "Ha", pronounced "haaah!", is sort of the opposite of "Heng": the abdomen temporarily expands with a momentary pulse, but the abdominal "ball" rolls "upward", and the diaphragm rises, decompressing the abdominal cavity; it is commonly used to dissipate the force of an opponent's strike, and also in a maneuver called "suddenly disappearing"... An analogy would be when a stunt double in a movie jumps or falls from a height onto an airbag - there are vents in the side of the air bag to dissipate the initial impact shock by suddenly letting out a controlled amount of air.
When you practice 'Heng-Ha" for awhile, the contrast soon becomes obvious: "Heng" - throat closes, diaphragm drops, abdomen moves forward and down; "Ha" - throat opens, diaphragm rises, abdomen rolls upward and back.
After awhile, these sounds become barely audible, but they're still very functional; when you're sparring with Wm. Chen and you hear him make that low "hunghh!" sound, you know he's about to hit you hard enough to hurt your whole family!
