PART 1: The basics and the benefits of the Frenzel technique.
For many freedivers equalizing is the limiting factor when diving for depth. Some run into problems immediately after leaving the surface, others at a certain depth. This is felt as a growing pain in the ears, which should be taken as a signal to abort the dive.
The Valsalva technique is the most common equalization method, and for most it permits dives to reasonable depths. The strength of this technique is the ease of its execution: almost anyone can learn to …pinch the nose shut and blow against it. However, the Valsalva technique is a very inefficient method of equalizing. It requires a surprising amount of muscular effort,
and it becomes rapidly more difficult as depth increases. In this series ofarticles we cover the physiological basis and exercises that can be used to learn the more efficient Frenzel equalization technique. In each article we focus on one type of exercise, and suggest “homework” which will prepare the reader for the next part.
Many divers do fairly well with the Valsalva technique, but for some even a few meters is too much when diving head down. The Frenzel technique requires more advanced muscle control and coordination than Valsalva, but usually the results make all the practice worthwhile.
The biggest difficulty with the Frenzel technique is that it requires independent control of the soft palate and the epiglottis. A good comparison is moving the eyebrows: it is hard to raise one eyebrow without raising the other. In addition to controlling the epiglottis and soft palate, successful execution of the Frenzel technique requires co-operation of the tongue and cheeks. All this can take quite a while to master, but with practice it will
become a natural part of diving.
The basic idea of the Frenzel technique is very simple. If the volume of a closed airspace is mechanically reduced, the pressure inside the airspace will increase. If there is a hole in the wall of the airspace, air will flow through the hole until the pressure is the same on both sides of the wall. This is the principle behind equalizing the pressure in the middle ear. In the Frenzel technique the closed airspace is the mouth. When the epiglottis, soft palate and mouth are closed (see attached picture), and the volume is reduced by for example squeezing the cheeks, the pressure will increase until air escapes, most likely via the mouth accompanied by some funny noises. Unlike with Valsalva, the diaphragm and lungs do not need to work at all, in fact Frenzel will work even if the lungs are completely empty. This is why the Frenzel technique is very useful on dives deeper than 25 meters when getting air from the lungs can be very difficult. Another advantage is that the pressure generated with this technique is much higher than with Valsalva, which enables even people with “tight ears” to equalize.
However, the aim is not to direct air out through the mouth. Air should flow into the middle ear through the eustachian tubes. The openings to the eustachian tubes are in the nasal cavity. The movement of air between the mouth cavity and the nasal cavity is controlled by the soft palate, which should be opened while keeping the epiglottis closed
(otherwise air would flow back into the lungs). This is maybe the
most difficult part of learning the technique. The nose must also be
pinched closed to prevent air from escaping that way.
- The mouth is closed and full of air.
- The epiglottis is closed.
- The nostrils are pinched shut.
- The soft palate is in the neutral position.
As the pressure is increased by squeezing the cheeks (actually thetongue should also be used, but we will get back to this later) air will try to enter the lungs, but the epiglottis will prevent this. Air will try to escape through the mouth, but it will be stopped by the closed lips. Air will try to find its way out through the nose, but since the nose is pinched shut it will have to find the only other way, which is to enter the eustachian tubes and equalize the pressure in the middle ears.
The following pictures illustrate the differences between the two techniques. Note that with the Valsalva technique air comes from the lungs, and with the Frenzel technique air comes from the mouth cavity. Because of the smaller volume of the mouth cavity, the same (or greater) pressure can be created with much less movement and work.
PART 2: The soft palate.
The soft palate is a small muscle which directs air from the palate to the nasal cavity. When breathing through the nose, the soft palate is always open, allowing air to flow from the nose to the trachea. When breathing through the mouth it is usually closed subconsciously (upper position). The following picture should clarify this:
Note that the openings to the eustachian tubes are in the nasal cavity, behind the soft palate. This is why the soft palate must be in the neutral position (as it is in the picture) to allow airflow from the mouth cavity to the eustachian tubes.
The soft palate is also used when speaking, especially in words with the ng-sound as in the word “dong”. This means that you already can control the soft palate, now you just need to learn how to control it consciously.
Say the word “dong” and try to feel what happens around your palate. You should notice a small change. Say “dong” again, but this time prolong the end of the word: “donggggggggg”. You should feel a vibration in your nose and palate. Now stand in front of a mirror. Plug your nose and say “dongggggggg” again. The soft palate tries to direct the air out through
your nose as you make the sound, but you prevent this by pinching your nose. The word should quiet down towards the end and your nose should bulge. Keep practicing this until you can feel the soft palate moving.
You can also try the following exercise: make a continuous humming sound and every now and then interrupt the humming by making the ng-sound. When you can repeat the sound as fast as in the example, you are ready to move on to the next exercise.
Now instead of humming, practice the same thing with a normal exhale. Keep your mouth open and try to direct your breathing alternately through the nose and the mouth. If your are not sure which way the air is going, keep your hand under your nose to feel the airflow. Remember to keep your mouth open all the time when doing this exercise.
When exhaling through the nose, the soft palate is in the lower position. When exhaling through the mouth, it is in the upper position. The Frenzel technique requires the soft palate to be in the neutral position, allowing the air to flow through both at the same time. This is the aim of the final exercise. Take a deep breath. Exhale slowly, alternately through the nose
and the mouth. Stop the soft palate in the middle of these positions. The air should flow simultaneously from the nose and the mouth. This exercise is the core of part 2. The purpose of the other exercises was to learn to feel the movements of the soft palate.
Repeat these exercises until you can control your soft palate at will. Just don’t let anyone hear you making the various sounds or you might get a strange reputation! The next part will focus on the epiglottis.
(Read: “Next part”)