ANATOMY OF AN EAR

The ear is the organ of hearing and balance. Understanding its anatomy can help better illustrate why it’s essential to equalise. The ear consists of three distinct spaces filled with either air or liquid: the external, middle and inner ear.

As divers descend in the column of water, environmental pressure on the body increases in a linear fashion across the body.

To prevent pressure-related injuries such as bleeding, 0edema (swelling) of soft tissues, leakage of fluid into the air space and membrane rupture, divers must actively enable air from the throat to enter through the eustachian tubes into the middle ear by using equalisation techniques.

Why You Must Equalise

AT 1 METRE

The water pressure outside of your eardrums is 10 percent greater than the pressure in your middle ears. Your eardrums flex inward to compensate – you may feel some pressure

AT 2 METRES

The pressure differential is 20 percent greater than at the surface and your eardrums bulge further. You feel definite pressure, and many begin to feel pain

BEYOND 2 METRES

Your eardrums are stretched to their limits. Unless you have equalised, you will feel significant discomfort or pain. The tissues and blood vessels in your ear may start to break, and as the pressure differential builds, your eustachian tubes will shut, making equalisation impossible

AT 3 METRES

If your eardrums haven’t broken yet, the pressure differential begins to draw blood and fluid from the surrounding tissues into your middle ears, causing middle-ear barotrauma. Pain may become a feeling of fullness which will remain for a week or more

BEYOND 3 METRES

If you haven’t equalised, your eardrum can break and cause water to flood your middle ears. The sudden exposure can cause vertigo

HOW TO EQUALISE

There are several techniques divers can employ to effectively equalise their ears.

  • PASSIVE
    Requires no effort. Occurs during ascent
  • VOLUNTARY TUBAL OPENING
    Try yawning or jaw wiggling
  • VALSALVA MANOEUVRE
    Pinch your nostrils and gently blow through your nose
  • TOYNBEE MANOEUVRE
    Pinch your nostrils and swallow (good technique, if equalisation is needed during ascent)
  • FRENZEL MANOEUVRE
    Pinch your nostrils while contracting your throat muscles and make the sound of the letter “k”
  • LOWRY TECHNIQUE
    Pinch your nostrils and gently try to blow air out of your nose while swallowing  (think Valsalva manoeuvre meets the Toynbee manoeuvre)
  • EDMONDS TECHNIQUE
    Push your jaw forward and employ the Valsalva manoeuvre or the Frenzel manoeuvre

PRACTICE MAKES PERFECT

Divers who experience difficulty equalising may find it helpful to master several techniques. Many are difficult until practised repeatedly, but this is one scuba skill you can practise anywhere – in a pool, on a plane or even at your desk. Just do it gently!

For the rest of this article and other stories from this issue, see Scuba Diver No.113 Issue 3/2018

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