tomyum:
But I could not really do that equalize thing, at all. How do you do it while holding your breath?
The principles are the same free diving or on SCUBA.
To prevent a squeeze, which can cause barotaruma (pressure injury); it is necessary to equalize the pressure in the middle ear. The Eustachian tube connects the middle ear to the throat and makes equalization possible. The Eustachian tube is normally closed and must be opened to allow air to flow into and out of the middle ear. The Eustachian tube varies greatly among individuals. Factors that affect your ability to equalize the middle ear include partial obstructions, width, angle and shape of the Eustachian tube.
A number of methods exist which allow you to open your Eustachian tubes and equalize your ears. Equalizing the ears is frequently, although incorrectly, referred to as “clearing.”
The most common method of equalization is the Valsalva Maneuver. Named for Antonio Valsalva, this technique involves pinching off the nostrils and blowing gently into the nose. Never blow forcefully while attempting this method as a too forceful Valsalva Maneuver can result in the rupture of the eardrum, round window or oval window. This will usually result in immediate vertigo and hearing loss, which can be permanent.
The Frenzel Maneuver was named for developer, Herman Frenzel of the Luftwaffe in World War II. This method is preformed by closing off the vocal cords, pinching the nostrils and an effort is made to make a "guh" sound.
The Toynbee Maneuver is simply pinching of the nostrils while swallowing.
Beance Tubaire Voluntaire (BTV) or Voluntary Tubal Opening is the preferred method of equalization once mastered. It feels very much like a yawn and a difference in tonal quality of sounds will be noticed when successful. The muscles of the upper throat are used to pull open the Eustachian tube.
You should employ equalization techniques immediately upon descent and continue them regularly on descent. If any pain is experienced, you should ascend until all pain disappears and begin again.
Often divers find it useful to chew gum or eat foods such as apples or carrots prior to diving. You should not attempt to chew gum or eat while diving. Another equalization technique divers find helpful is to gently massage the area under the ear, just behind the jaw. This gentle massage is most effective when used in conjunction with one of the other equalization techniques mentioned above.
If you are unable to equalize ear pressure, it is possible to rupture the eardrum, round window or oval window. This will usually result in immediate vertigo and hearing loss, which can be permanent. If you are unable to equalize, you should abort the dive.
Reverse blocks are also fairly common in the middle ears.
The use of earplugs will create an air space in the outer ear that you will be unable to equalize. This can result in injury so you should never dive wearing non-vented earplugs.
Another air space subject to squeeze on descent is the air space intentionally put in front of the diver’s eyes. The pressure in the mask must also be equalized, fortunately this is very easy to accomplish by simply exhaling a small amount of air into the mask through the nose. Failure to do so will result in mask squeeze. A mask squeeze can cause bruising of the soft tissues of the face covered by the mask as well as ruptured blood vessels in the eyes. Swim goggles should never be used when diving as they can easily cause injury to you eyes.
