I’ve only done scuba to depths of around 70-80 feet and my eardrums were already hurting badly then. On super-deep dives, such as into the 800-foot-deep Bushman’s Hole in South Africa, are scuba divers wearing some sort of protective headgear to protect their eardrums from direct contact with water pressure?
If so, does that inhibit their hearing?
If your eardrums hurt on any depth dive, you aren’t doing it right. Seriously. You should be equalizing the pressure in your middle ears via the Vasalva maneuver or some other equalizing technique. I’ve been down over 100 ft many times without any pain whatsoever. Conversely, I’ve had dives where I had to give up because I couldn’t go below 10 ft. without blinding pain because of a blocked Eustachian tube.
Thanks, good advice. But as far as the thread question is concerned - surely there is a point - maybe 400, 700 feet - where the pressure is simply so great that the eardrums cannot cope, right, and protective gear would be needed?
No, because if you’re equalizing pressure then the pressure inside your eardrum is the same as the pressure outside. I agree with muldoonthief. If your ears hurt, you’re doing it wrong (or have a medical issue that’s impacting your dive).
There limit on human dive depth is (I believe) the point at which there’s no conceivable gas mix that you can breathe at the pressures required.
Nope.
The pressure needs to be equalized. Even a few PSI will cause pain.
BTW, ears are not the only cavity in the body that can cause pain - sinus and intestines can have air pockets that can also cause a “squeeze” as the divers call it.
Nope, theoretically not. If you allow time for equilibration, your ears should feel no effect. There are some technical limitations on amount of air and thus time one can take.
Agreed with the above; the eardrums do not limit dive depth. I have trouble equalizing when I’m snorkeling and make a quick breath-hold dive to 5-10 feet depth, because I’m descending very quickly and head-down, but I have no trouble going to 110 feet on scuba.
There are problems that arise with greater depths, and they can involve the ears, but it’s not really a matter of not being able to equalize. On that deep dive in Bushman’s Hole where Dave Shaw died, his buddy Don Shirley experienced DCS in his ear on the ascent, which caused vertigo, which caused him to vomit repeatedly and almost lose the line to the surface. If he hadn’t managed to grab on, he would almost certainly have died too. But again, that wasn’t an equalization issue, and Dave Shaw had previously dived all the way to the bottom of the hole and come out with eardrums intact.
“Equalizing” means admitting/forcing air into your eustachian tubes so that the pressure on the eardrum’s proximal surface (that is, the side exposed to the eustachian tube) is equal to the pressure on the distal surface (that is, the side exposed to sea water pressure).
Pain is caused when the eardrum is distorted by a pressure imbalance. If you have equalized the pressure, then there is no distortion and no pain.
If you experienced ear pain during a dive, then it is because you did not adequately equalize pressure.
If you were able to dive down to 70-80 feet without rupturing your eardrums, then you were able to equalize the pressure at least somewhat; your pain during those dives just means you didn’t equalize the pressures enough to prevent painful eardrum distortion.
No matter how much pressure the ocean applies to the distal surface of the eardrum, there is a pressure you can apply to the proximal surface that exactly balances it and results in no ear pain.
If you’re having pain you really need to stop descending until you can equalize, and abort the dive if you can’t. Some people just struggle with equalization more than others, but it’s really important that you figure it out if you’re going to keep diving. Pain is a sign you’re about to seriously hurt yourself if you haven’t already. There are lots of resources online about different methods of equalization that might work for you. One thing they really should teach more often, because it’s so easy and effective, is to pre-pressurize by performing a Valsalva (hold your nose and gently blow) on the surface, before you even start your descent.
Another issue that you have to keep in mind is to ensure that your ears equalize as you ascend. Usually, your ears equalize on ascent more or less automatically, but sometimes do not, especially if you ascend too quickly. If you fail to to equalize on ascent, you can experience what is called “reverse squeeze.” The symptoms are ear pain as you ascend.
The correct solution is to go back down deeper until the pain goes away, and to equalize your ears again. Once you have successfully equalized, you should then slowly ascend, and continue to equalize more frequently.
What you don’t want to do is to ignore the pain and keep ascending. My son did this on a dive a couple of years ago, and was in severe pain for several hours after the dive.
The best way to avoid problems with equalizing is to equalize frequently. if you have any problems going up or down, stop and go back (shallower if you are going down, and deeper if you are ascending) until the pain goes away, then equalize. Note that if you change depth too fast without adequately equalizing, sometimes you find you can’t equalize, because the difference in pressure inside and outside the ear is too great, and the Eustachian tube(s) can get pinched off. That’s why you sometimes need to reduce the differential pressure so that you can equalize.
Difficulty equalizing can also be caused by congestion due to allergies or a cold. This is why diving with a cold is contraindicated. It can be dangerous to counteract this with cold medicine, because if the cold medicine wears off during the dive, you might find yourself unable to equalize during ascent.
Extreme depth does not make equalizing significantly more difficult. Though the breathing gas becomes slightly more dense at extreme depth due to increasing pressure it is actually easier as there is a lower percentage change in gas volume per meter of descent at extreme depths.
No, technical divers (dives deeper than 130ft/40m) do not use special headgear to protect against equalization. It wouldn’t help and would almost certainly result in severe injury. The only way to make that work would to be to use an atmospheric diving suit, essentially a one man submarine with rigid articulated body segments.
Physiologically one other consequence of failing to equalize the middle ear is that tissues surrounding the middle ear space can secrete a transudateand partially fill the middle ear space with fluid. That can lead to easier equalization in the immediate moment but provides an excellent medium for infections organisms to grow. This can occur at modest recreational depths and is not unique to technical diving.
I have one nitpick with your post. The density of breathing gas is (approximately) related directly to pressure, so if you are surrounded by 3 times the surface pressure, the gas density is about 3 times as high as on the surface. So the density of the gas does not rise only slightly.
This starts to be an issue for depths >120 feet, since increased density leads to increased breathing resistance. This can mean that your breathing muscle activity starts to create more CO2 than it removed from the system.
The percentage change in gas volume per meter of descent works out like this…
At the surface suppose your lung volume is 120 units. The pressure above you is atmospheric pressure, call it 1atm.
At 10 meters underwater you still have the pressure of the atmosphere (1atm) above you plus the pressure of 10 meters of water. The pressure exerted by 10 meters of water is 1 atm. So the total pressure you are under is 2atm. That means that (if you don’t inhale pressurized gas from a scuba tank) that your lungs will be compressed to half their volume at the surface – to 60 units, a 50% decrease in volume over 10 meters.
Keep going down. Descend 10 more meters to a depth of 20m. Still 1atm of pressure from the air above plus 2atm of pressure from the water column. Total of 3atm of pressure. Lungs now compressed to 40 units… a 66% reduction from the surface but only 33% reduction from where you were at the 10 meter depth.
Descend again. At 30m depth it is 1atm of air pressure plus 3atm of water column pressure. Total of 4atm of pressure. Lung volume compressed to 30 units… a 75% reduction from the surface but only a 25% reduction from the 20 meter depth.
And so on. At 110 meters depth it is 1atm of air pressure plus 11atm of water column pressure. Total of 12atm of pressure. Lung volume compressed to 10 units… a 91.6% reduction from the surface and a mere 8.3% reduction from the 100 meter depth.
The effort to equalize varies according to the percentage change in volume. You need to equalize your ears early and often, every couple of meters, as you descend from the surface. At more extreme depths you can drop 10 or more meters at a time with comparatively little need to equalize.
Divers run into other problems at extreme depth. Nitrogen narcosis and oxygen toxicity become controlling factors before the density of breathing gas and thus the work of breathing becomes the issue. The solution to the dilemma is to switch to gas blends that are specialized for the target depth range. Most common is trimix, a blend of helium, nitrogen, and oxygen. Rarer is heliox, a helium and oxygen blend. Other exotic gas blends involving hydrogen as a breathing gas have even been used. These gas blends with helium or hydrogen have a lower work of breathing than compressed air.
Is that the same idea as “gas pains” i.e. air pockets in your intestines that cause pressure - and pain - from within?
Yes, sort of. Intestinal pain would mostly be an issue at the end of a dive, something referred to as a reverse squeeze Indeed pain from expanding gas in the intestines can be brutal until you can, ahem…, naturally release some of that gas.
If you are having some gas issues it will suddenly feel better as you descend at the start of a dive. The gas pockets in your intestines get squeezed to a small volume, albeit at higher pressure, as you go down in the water column. This reduces the stretch the intestinal walls sense and relieves any pain.
But those bacteria and other microorganisms in your intestines keep generating gas during your dive! This adds more gas molecules to your gut, which is probably all fine and good until your need to ascend at the end of the dive!
Now as you ascend there is less pressure around you and the gas bubble in your intestines starts to expand. That is fine until the expanding gas starts to stretch the intestinal wall like an expanding balloon! Ouch! If you cannot remove some of that gas you will need to descend a bit until the pressure differential is not so great and then hopefully gently release some gas as you ascend slowly. Unfortunately if you just cannot vent some gas you will need to eventually surface even if it causes injury.