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Yes, you heard that right. Using your ears as a depth gauge. This is something that can work for all divers

The training that I've completed contained some very strange ideas...ideas that when I first heard them thought they were typical military acronyms or worse for something totally unrelated.

It was 0830hrs on a cold wet day sitting patiently watching the golfers above our location for the days briefing. It was all about 'ears'..great!

'Extended Atmospheric Residual Symptoms' said Boz...followed by an uproar of laughter from the rest of the guys. To a certain extent he may just have been right but it certainly gave us all a moments on joy. After the briefing however it all made sense.

The ears are a complex marvel of nature's ingenuity and complexity to overcome one of the primary senses - hearing.

But the ears also have a rudimentary second function - that of balance in conjunction with sight. However, when one of these two is disturbed for whatever reason you may experience dizziness or loss of balance. The eyes are used to help orientate yourself about our surroundings which is further complicated by donning a mask (causing initial visual disturbances but after a while your brain takes this into account). Within the ears the vestibular system detects movement and motion, motion detected as circular and straight. Within the vestibular system are a number of tubes and sacs filled with fluid plus a whole mass of special sensor cells. When we move the fluid is disturbed and the sensory cells send various signals to the brain for interpretation.

So, where is this leading you may ask. Well, the above scenario also detects pressure displaced from the Tympanic Membrane (commonly known as the ear drum) via the middle ear and eventually to the Eustachian Tube. Should the pressures anywhere within the system not be equal then sensory nerves send signals to the brain depicting 'pressure'. I realise this is a simplistic view but it gets the idea across.

Diving at ten meters doubles the atmospheric pressure (again rounded to avoid complicating the issue) placed on the ear drum resulting in an imbalance of pressures. As divers we swallow, burp, wiggle our jaws in an attempt to shift the pressure imbalance via the Eustachian Tube so all is equal. We've all done it.

So, what does this mean to us? Well, the ears are exceptionally sensitive. So much so that you probably end up wiggling, burping and farting your way to inner ear pressure balance every 2 or 3 meters as you decend. Next time you dive look at your dive computer or pressure gauge and for every equalization technique you use check the depth. Everyone is slightly different so perservere. The idea is to find out generally what is happening in the first ten or so meters from the surface. This is generally considered the most prominent diving area for pressure related issues as this is where the biggest changes occur.

Everyone is reliant of their depth gauge or computer these days - so what happens when the lights go out under water?

I'm not necessarily talking about your torch nor am I talking about operational military diving at night but there may become a time when all hell breaks loose and the last depth you remembered was twenty four meters using your favourite 40% Nitrox. The lights are 'out', you're disorientated, your computers failed and panic is setting in. Your 'popped' your ears twice during your manoeuvres...Are you now ready for the O2 convulsion that's about to set in?

Okay, a dramatic analogy but us military divers are taught quite early on the use of the ears. Set your depth (usually quite shallow for most of us, around 10-12 meters) and get to a point slightly above this where the pressure in your ears has built up slightly. And I mean slightly - not excessively otherwise your going to do some damage. Then try and maintain your depth without looking at your depth gauge. If you have to 'pop' your ears then you've broken the depth line. If you release yourself from the pressure then you're above your desired depth. It's a useful exercise but remember that were all different. If you're a 'jaw wiggler' or suffer from 'middle ear creep' then the pressure may slowly dissolve and you'll find yourself getting deeper and deeper with realising it. Always back up the above method with a depth gauge/computer and constantly verify that your staying put. Don't risk binning your gauges after six months of trialling this exercise. . Don't risk binning your gauges ever!!! This is a military test and good for when all else is failed and should NEVER replace standards laid down by your training establishment.

But it's a good exercise to remember - to quote our instructor:

'Ears are not for hearing - they're for depth control only. This exercise will be useful one day. It will save your life'.

I've never had to use it...yet.

Scuba Steve - Submitted anonymously and rewarded with a free copy