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The Frenzel Equalization Technique

Years ago, I took my first freediving course.  Although I had been scuba diving for many years prior, I was disappointed that I could go down to 7 meters only, feet first.  I only knew how to equalize using Valsalva.  The Valsalva maneuver is performed by moderately forcing an exhalation with the mouth and nose closed, a method that mainly uses the abdominal muscles which requires a lot of energy, but  is very easy to learn, very easy to teach, and works well on scuba.

Equalization needs a pocket of air to work, the more the better.  This is one of the reasons why equalizing is easier on scuba, there’s plenty of air.  Because air is compressible under pressure, the volume of air inhaled just before a freedive becomes less and less as you go deeper, making equalization more and more difficult.

Curious to see if I could freedive any deeper, I went off to find more information on equalization.  There was only one document about Frenzel equalization that existed at the time and it had outdated and limited information, but it was enough to learn from.  It took me a long time to learn; but with proper instruction, and with a lot of resources online now, it’s not uncommon for students to pick it up after a couple of days, overnight or even within a day.

Frenzel is a much better equalization method in many ways particularly in freediving where energy conservation is critical.  It’s doesn’t require much effort at all once mastered and is the foundation for the more advanced equalization method used in even deeper freediving.

Frenzel requires good control over certain muscles – the glottis, soft palate and the larynx.  While some do it naturally, some will have to learn.  Tricky enough in the beginning, but it can be learned.  Some pick it up faster than others, but it can be mastered by anyone.

The Frenzel Technique

In Frenzel, the surrounding the larynx compresses the trapped air in the back of the mouth.  The pressure forces the air to enter the nasal cavity and tries to escape out the nose, but the nostrils are pinched shut.  Air cannot escape back into the lungs because the glottis is closed.  Air cannot escape out the mouth because either the tongue applies an airtight seal or the mouth is closed.  Nowhere else to go, the air enters the eustachian tubes and into the middle ear equalizing the pressure.

The 4 elements to performing Frenzel

The first element is to have a closed glottis.  Where and what is glottis?  Glottis is the opening between the vocal cords in the throat.  You can make the “aahhh” sound and by stopping the sound, with your mouth open, you are closing your glottis.  You can also try inhaling fully through the mouth and then, while keeping the mouth open, hold the air in the lungs by closing the glottis.  Super easy, right?

The 2nd element?  Soft palate in neutral position.  Soft palate is a soft fleshy part toward the back of the roof of the mouth.  If you drew a line with your finger from the back of your upper teeth all the way back until you start to gag, that’s where the soft palate is.  Inhale big and with an open mouth, exhale very slowly out the nose, then mouth, then nose again and keep switching until you run out of air to exhale.  Every time you switch, the part that you feel you’re raising and lowering is the soft palate.  How do we determine if the soft palate is in neutral position?  It is when you can exhale out the nose and the mouth at the same time.  We can do it very easily.

As you’ve noticed, controlling the glottis and the soft palate is not at all difficult.  We do it all the time whenever we talk – whenever we make oral and nasal sounds!  What’s difficult is controlling them together.  When you close your glottis, you will likely raise your soft palate.  But we need to have the soft palate in neutral position.  Try this: inhale fully through the mouth and then, with the mouth open, hold the air in the lungs by closing the glottis.  While holding the air with closed glottis, play with raising and lowering (relaxing) the soft palate.  Remember what neutral soft palate feels like – it actually feels the most relaxed and natural so that makes it somewhat easier.

The 3rd element is you need to be able to trap some air in the back of the mouth by performing a tongue block.  The tongue block is achieved by sealing the tongue against the upper teeth as when you say the letter “t”.  Remember that it should always feel like there is air between the roof of the mouth and the tongue.  Obviously, if there is no air to pressurize, equalization will not be possible.

The 4th element being you need to be able to pump the larynx up and down (while keeping the tongue block or the mouth closed) to pressurize and force the air up the eustachian tubes. Keep in mind that this motion will feel like you’re compressing with the back of the tongue. While there are other ways to learn to control the larynx up and down, I have always just visualized either squirting water (or air) through the teeth or through the mouth (without using your abdomen, of course).  Another good way to familiarize yourself with moving the larynx down is by moving the tongue back towards the throat.  This movement is the down position of the larynx.  Looking at a mirror, you should clearly see the up and down movement of your Adam’s apple.  Once it feels like the larynx and tongue are flushed against the roof the mouth, reset as if you’ve just refilled the back of the mouth with more water (or air) to squirt again.  Doesn’t get any easier than that!


It is also possible to perform Frenzel using the “k” block instead of tongue or “t” block.  Try to say “kah” without making the sound.  There are other blocks I’ve heard people use – “p”, “h” and “n”, but anyway…  Whatever block you choose, remember that it should always feel like there is a pocket of air in the back of the mouth.

Putting everything together

With the nose pinched, perform a tongue block making sure there is a bubble of air trapped in the back of the mouth, close the glottis, and then pump the larynx. Did you feel your ears pop?  It might take a few or even many tries, but if you feel you’re missing something, read on…

Possible problems

  • Pressurized air escapes down the throat instead of up the eustachian tubes due to open glottis.
  • Pressurized air cannot get to the nasal cavity due to raised soft palate.  Try to remember how relaxed soft palate should feel like.
  • Pumping the larynx does not create pressure due to tongue not having a good block.  Without an airtight seal, all you’re doing is aimlessly pumping the larynx in the air space inside the mouth.
  • No pocket of air to compress in the back of the mouth.  Keep in mind that if there isn’t enough air to compress, you will not be able to equalize until you move a bubble of air in in the back of the mouth again.

Practice Tips

  • Practice with your head down to simulate normal freedive position.  Lie belly down on a bed, table or any structure that can safely support your body, with your head down hanging from the waist.
  • Pinch the nose lightly to let a small amount of air escape every time you equalize to simulate decreasing volume of air.  Practice moving air from the lungs to the mouth as you run out of air to equalize with.
  • Do it 500 more times after you think you get it as it needs to be mastered before taking it in the water.  Simply understanding how it works or by being able to do it a few times just doesn’t cut it.  Being in inverted position underwater, plus the many added distractions in the water, make it even harder to perform Frenzel if you have yet to master it.  Fortunately enough, it’s easy to find time to practice – while watching TV, reading a book or while lying in bed.

Good luck and I hope that you find this material helpful.  Should you have a question, comment or suggestion, please don’t hesitate to send us a message via Facebook, Instagram or dumagatfreedive.com.

To learn the more advanced Frenzel-Mouthfill equalization method, see our Deep Equalization Technique: The Mouth-fill article.


This article is geared towards providing beginner to intermediate freedivers an easy, user-friendly and practical way to learn and understand the Frenzel equalization technique. The information herein is offered solely as informational and not intended as a substitute for instruction from equalization experts or from attending a formal freediving course. Freediving and breath-holding can be dangerous if practiced without proper knowledge and education. They should be practiced with a trained buddy or a qualified instructor. Attend a formal freediving course.

December 1, 2014 | Emil Lars