The two previous posts were about the small internal muscles involved in equalization and the routines and tricks to learn hands-free equalization. This post is about continuous vs intermittent equalization. Should we keep the auditory tubes open constantly to allow free air flow, or is it better to equalize from time to time? Indeed there are two possibilities:
1/ constantly tense the muscles opening the auditory tubes; this will keep the tubes open throughout an entire dive and the pressure inside the ears and mouth and nose will remain equal;
2/ wait until the eardrums feel water pressure and signal a need to equalize; only then activate the muscles to open the tubes; such hands-free equalization is intermittent;
Which option is best and why?
In an ideal world disregarding not ideal differences between people it seems keeping the tubes open is better. + keep two pairs of muscles contracted: a pair of "tensor veli" going from the palate sideways and then up towards the auditory tubes and opening them, and a pair of "palatoglossus" going from the palate down into the tongue (and parallel to the "palatopharyngeus" we discussed in the part 1 of this equalization story). The tubes remain open, while the palate is somehow shortened and retracted forwards from sealing the passage from mouth to nose. Air flows freely from the larynx all the way up to the inner ears. + the eardrums would be constantly free from any excessive tension, equalization being constantly there; + no need to think of any complicated movements with the palate elevators or depressors (i.e. "levator veli" and "palatopharyngeus" from part 1), so conscious attention will be free to do other useful stuff: scan and relax the body, and control the closed vocal folds to keep the mouthfill; + no need of pushing air from the throat or cheeks up, thus no useless efforts neither risk of "swallowing" the mouthfill back into the lungs;
There is a problem though. Auditory tubes are made different in freedivers. Some tubes open wide. Other tubes open just a little. Some freedivers have short tubes. Others are long and sinuous. Tubes opening muscles are also different. Some freedivers can open the tubes with a slight effort, others must ostensibly tense the muscles. And they can not keep the tubes open for any time long.
It is about luck being born this or that way.
Start by trying both ways of hands-free equalization, constant and intermittent, even if constant would appear challenging for your inner-nose anatomy. Sometimes though the constant openness of the tubes will appear truly impossible.
In such a case stay positive and opt for intermittent equalization.
Practicing it, keep in mind the following: + After practicing on land the constant hands-free may become possible; practice your tube-opener palate-stretcher "tensor veli" muscles (use the trick with earbuds-headphones in the nostrils from the part 1 for example). + Take care to keep some tension in the downwards "palatoglossus" muscles connecting the palate and the tongue. For simplicity sake we did not elaborate on those in part 1. The importance of these muscles is not universal to all freedivers, but it is clearly needed for some. After an equalization all palate muscles relax. If the soft palate is somehow longer than usual, it'll reach the rear wall of the throat, sealing air passage to the nasal cavity. After a relaxation, as the dive progresses deeper, some lowering of air pressure in the nose will build up, forcibly sucking the palate to the passage from mouth to nose. At the next attempt to equalize the palate might be reluctant to open up the nose again. Keeping some "palatoglossus" tension between intermittent equalizations is a good habit for keeping the palate retracted and the nasal cavity constantly connected to the mouth, preventing this palate-suction problem. + In a dive with intermittent equalization the drums will be stretched by water pressure, so it's good to anticipate and equalize in time before feeling any pressure on the eardrums. + Remember to control your tongue by not letting it up; indeed while keeping full attention on these palate-tongue "palatoglossus" muscles to keep the passage to the nose open, you might forget your tongue, and this one will just lift up and close the airflow into the nose anyway; In such case your cheeks might be bulging with a good stock of air, but no equalization would be possible; so keep your tongue under control too; + After each equalization the soft palate relaxes, so the vocal folds might relax too, letting the mouthfill escape back into the lungs; think of keeping the vocal folds closed; + Practicing hands-free intermittent equalization, remember to avoid forcefully pushing air up into the nose, i.e. avoid using muscles other that those "tensor veli" stretching the soft palate to equalize; + Intermittent equalization is a well-coordinated action of small muscles; your attention should simultaneously go to the tongue, to the soft palate, the vocal folds, while also relaxing the body to save oxygen; as any other learned coordination, it improves with practice; + Sometimes if your intermittent equalization fails, moving the jaw down-and-forward might help a great deal;
This hands-free intermittent equalization is doable and somehow crucial to learn, though it seems difficult at the beginning. Myself I equalize with intermittent, sometimes helping it with the jaw movement.