Eli5, how is it that Scuba divers typically have to squeeze their nose and blow to equalize the pressure in their ears every few feet, but those who free dive can sink 20-30 feet in 10 seconds, and be fine while not visually equalizing?

Question

Is the ability to breathe what changes this, or is there some other technique behind it?

In: 55

Answer 1

SCUBA divers use a different technique (typically the Valsalva maneuver) to clear their ears.The Valsalva maneuver is similar to the action you’d take if your altitude changed on a mountain or in an airplane: plug your nose and breath out using your diaphragm.

That’s not necessarily the optimal technique for free-diving, however, because it can be unsafe for a free-diver: the Valsalva maneuver requires the expulsion of air from the lungs, which, for a free-diver, are compressed at depth. Using the Valsalva maneuver under such circumstances may cause injury to the lungs and ears.

Instead, free-divers typically use the Frenzel maneuver. That maneuver involves pinching the nostrils and putting the tongue in the position required to produce a ‘T’ or ‘K’ sound, while simultaneously closing the vocal folds and and lifting the larynx up to push the air from the mouth into the nose.

While the Freznel maneuver can be harder to learn because of the need for more muscle control, it doesn’t require air from the lungs (which means that dives can be longer and there’s less risk of injury), it uses smaller muscle groups, and it’s a much more controlled technique that works at greater depths than the Valsalva maneuver.

More information here:

[https://molchanovs.com/blogs/news/frenzel-vs-valsalva-equalization-for-freediving](https://molchanovs.com/blogs/news/frenzel-vs-valsalva-equalization-for-freediving)