Recently we tested our Facebook followers on ear safety and equalisation with a fun Facebook Quiz, which generated a lot of interest! However not everyone got 100% so we thought we’d share a few facts about ears and equalisation.
The 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 distinctive 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, edema (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% 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% 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.
DAN Insider 
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