Joe’s PADI IDC and Divemaster classroom
In this episode of the Joe's PADI IDC and Divemaster classroom, we will talk about air spaces, in particular the one most affected by water or hydro pressure. A subject covered during your divemaster course on Bali at Joe's Gone Diving.
Most of us experienced the uncomfortable feeling of pressure on our ears while being on a plane or driving to altitude. Here on earth, the pressure is around one bar and is getting less as you go higher. This pressure change is felt by our ears. The most affected part of the ear is the middle ear.
As you can imagine, being surrounded by a liquid like water which is heavier than air, the pressure increases more and more as we descend. Because the Water is pushing onto the tympanic membrane or eardrum and squeezing it, we need to push air against it to equalize it every few meters.
Looking at the diagram above and the ear's anatomy, explains how we hear and why we have to equalise. The ear is divided in three parts which a designed to catch sound and transport it to the brain.
Outer ear: traps sound waves in air or water and channels them down the ear channel (auditory channel) to the eardrum (tympanic membrane) into the middle ear.
Middle ear: the eardrum forms an airtight barrier separating the outer ear from the middle ear. The sound waves vibrate on the auditory bones (ossicles) where they get magnified, to pass into the cochlea and the inner ear.
Inner ear: the cochlea is an liquid filled organ, with the magnified pressure waves the round window is pushing in and is vibrating and stimulating the auditory nerve which is connected to the brain and understood by it.
Your outer ear is open to the environment and therefore always in equilibrium with the surroundings. The inner ear as we learned, is liquid filled and therefore unaffected by pressure. However the middle ear is dry and gas filled.
Your middle ear is connected to your throat via the Eustachian tube. You equalise or compensate the altered pressure by pushing/blowing gas from your throat through the Eustachian tube into the middle ear to restore the pressure balance on both sides of your eardrum/tympanic membrane.
You can accomplish this equalisation in two different ways either the Valsalva maneuvre or the Frenzel maneuvre.
Valsalva maneuvre: you pinch your nostrils and blow gentle against it which relaxes the tissues around the Eustachian tube and forces air through it. This method however, can be dangerous if you perform it forcefully as you could rupture the round Window.
Frenzel maneuvre: this method is a little bit more advanced and might need some practise, however it is safer so you might want to start using this one as a dive professional. The Frenzel maneuvre is done hands free and you basically use your throat muscles to force air into your middle ear for equalisation.
Stayed tuned for our next Blog in Joe’s PADI IDC and Divemaster Course Classroom when we’ll talk about Skills and Environment.