How Your Ears Respond to Pressure. 6 Methods to Equalise Your Ears.
10 Tips that Make Equalising Easier. How to Deal with Other Ear Problems.
DAN’S SMART GUIDE TO EAR EQUALISING
The purpose of this Smart Guide is to help you understand how your ears respond to pressure and the best ways to protect them while scuba diving.
From simple cases of swimmer’s ear to the serious and sometimes lasting damage of barotrauma, divers are vulnerable to ear problems because the delicate mechanisms that govern our hearing and balance just aren’t designed for the rapid pressure changes that result from diving.
FORTUNATELY, EAR INJURIES ARE PREVENTABLE.
Your middle ears are dead air spaces, connected to the outer world only by the Eustachian tubes running to the back of your throat.
If you fail to increase the pressure in your middle ears to match the pressure in your outer and inner ears, the result is painful middle ear barotrauma, the most common pressure-related ear injury.
The key to safe equalising is opening the normally closed Eustachian tubes. Each has a kind of one-way valve at its lower end called the "Eustachian cushion," which prevents contaminants in your nose from migrating up to your middle ears. Opening the tubes, to allow higher-pressure air from your throat to enter your middle ears, normally requires a conscious act. Swallowing usually does it.
You equalise your ears many times a day without realising it, by swallowing. Oxygen is constantly absorbed by the tissues of your middle ear, lowering the air pressure in those spaces. When you swallow, your soft palate muscles pull your Eustachian tubes open, allowing air to rush from your throat to your middle ears and equalise the pressure. That's the faint "pop" or "click" you hear about every other swallow.
Scuba diving, however, subjects this equalisation system to much greater and faster pressure changes than it’s designed to handle. You need to give it help.
WHY YOU MUST EQUALISE
At 1 metre(3 feet)
At 2 metres (6 feet)
Beyond 2 metres (6 feet)
At 3 metres (10 feet)
Beyond 3 metres (10 feet)
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.
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.
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.
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.
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
All methods for equalising your ears are simply ways to open the lower ends of your Eustachian tubes, so air can enter.
PINCH YOUR NOSE AND BLOW (VALSALVA MANOEUVRE)
This is the method most divers learn: Pinch your nostrils (or close them against your mask skirt) and blow through your nose. The resulting overpressure in your throat usually forces air up your Eustachian tubes.
But the Valsalva Manoeuvre has three problems:
1 - It does not activate muscles which open the Eustachian tubes, so it may not work if the tubes are already locked by a pressure differential.
2 - It's too easy to blow hard enough to damage something.
3 - Blowing against a blocked nose raises your internal fluid pressure, including the fluid pressure in your inner ear, which may rupture your "round windows". So don't blow too hard, and don't maintain pressure for more than five seconds.
Swallowing—and various methods of equalising—are all ways of opening the normally closed Eustachian tubes, reducing the pressure differential between the outer ear and inner ear. The safest clearing methods utilise the muscles of the throat to open the tubes. Unfortunately, the Valsalva manoeuvre that most divers are taught does not activate these muscles, but forces air from the throat into the Eustachian tubes.
That's fine as long as the diver keeps the tubes open ahead of the exterior pressure changes. However, if a diver does not equalise early or often enough, the pressure differential can force the soft tissues together, closing the ends of the tubes. Forcing air against these soft tissues just locks them shut. No air gets to the middle ears, which do not equalise, so barotrauma results. Even worse, blowing too hard during a Valsalva manoeuvre can rupture the round and oval windows of the inner ear.
OTHER METHODS, SOME SAFER, INCLUDE:
Passive REQUIRES NO EFFORT
Typically occurs during ascent.
Voluntary Tubal Opening TENSE YOUR THROAT AND PUSH YOUR JAW FORWARD
Tense the muscles of the soft palate and the throat while pushing the jaw forward and down as if starting to yawn. These muscles pull the Eustachian tubes open. This requires a lot of practice, but some divers can learn to control those muscles and hold their tubes open for continuous equalisation.
Toynbee Manoeuvre PINCH YOUR NOSE AND SWALLOW
With your nostrils pinched or blocked against your mask skirt, swallow. Swallowing pulls open your Eustachian tubes while the movement of your tongue, with your nose closed, compresses air against them.
Frenzel Manoeuvre PINCH YOUR NOSE AND MAKE THE SOUND OF THE LETTER “K”
Close your nostrils, and close the back of your throat as if straining to lift a weight. Then make the sound of the letter “K.” This forces the back of your tongue upward, compressing air against the openings of your Eustachian tubes.
Lowry Technique PINCH YOUR NOSE, BLOW AND SWALLOW
A combination of Valsalva and Toynbee: while closing your nostrils, blow and swallow at the same time.
Edmonds Technique PINCH YOUR NOSE AND BLOW AND PUSH YOUR JAW FORWARD
While tensing the soft palate (the soft tissue at the back of the roof of your mouth) and throat muscles and pushing the jaw forward and down, do a Valsalva Manoeuvre.
PRACTICE MAKES PERFECT
Divers who experience difficulty equalising may find it helpful to master several techniques. Many are difficult until practiced repeatedly, but this is one scuba skill you can practice anywhere. Try practicing in front of a mirror so you can watch your throat muscles.
WHEN TO EQUALISE
Sooner, and more often, than you might think. Most authorities recommend equalising every every half metre to metre(m) of descent. At a fairly slow descent rate of 18m per minute, that's an equalisation every two seconds. Many divers descend much faster and should be equalising constantly.
The good news: as you go deeper, you'll have to equalise less often—another result of Boyle's Law. For example, a descent of 2m from the surface will compress your middle ear space by 20% and produce pain. But from 10m you'd have to descend another 4m to get the same 20% compression. When you reach your maximum depth, equalise again. Though the negative pressure in your middle ear may be so small that you don't feel it, if it's maintained over several minutes it can gradually cause barotrauma.
10 TIPS FOR EASY Equalization
LISTEN FOR THE “POP” Before you even board the boat, make sure that when you swallow you hear a "pop" or "click" in both ears. This tells you both Eustachian tubes are open.
START EARLY Several hours before your dive, begin gently equalising your ears every few minutes. "This has great value and is said to help reduce the chances of a block early on descent," says Dr. Ernest S. Campbell, webmaster of "Diving Medicine Online." "Chewing gum between dives seems to help," adds Dr. Campbell.
EQUALISE AT THE SURFACE "Pre-pressurising" at the surface helps get you past the critical first few metres of descent, where you're often busy with dumping your BCD and clearing your mask. It may also inflate your Eustachian tubes so they are slightly bigger. The guide here is to pre-pressurise only if it seems to help you and to pressurise gently.
DESCEND FEET FIRST Air tends to rise up your Eustachian tubes, and fluid-like mucus tends to drain downward. Studies have shown a Valsalva manoeuvre requires 50% more force when you're in a head-down position than head-up.
LOOK UP Extending your neck tends to open your Eustachian tubes.
USE A DESCENT LINE Pulling yourself down an anchor or mooring line helps control your descent rate more accurately. Without a line, your descent rate will probably accelerate much more than you realise. A line also helps you stop your descent quickly if you feel pressure, before barotrauma has a chance to occur.
STAY AHEAD Equalise often, trying to maintain a slight positive pressure in your middle ears.
STOP IF IT HURTS Don't try to push through pain. Your Eustachian tubes are probably locked shut by pressure differential, and the only result will be barotrauma. If your ears begin to hurt, ascend a few metres and try equalising again.
AVOID TOBACCO AND ALCOHOL Both tobacco smoke and alcohol irritate your mucus membranes, promoting more mucus that can block your Eustachian tubes.
KEEP YOUR MASK CLEAR Water up your nose can irritate your mucus membranes, which then produce more of the stuff that clogs.