axelrod@regina.DEC (02/07/86)
[] >Certain sounds seem to cause a popping sensation in my left ear.... >Also, my ears feel clogged quite often (perhaps due to nasal congestion). >Even when my congestion is cleared the problem still occurs... (Long article) (Sorry for the delay in getting this out to the net.) With the usual caution that I am not a doctor and may be theorizing a bit here, it sounds like your eustachian tubes are giving you the problems you describe. I suspect that you also feel discomfort in elevators and on airplanes. The eustachian tubes connect your middle ears (inside the eardrum but outside the cochlea and other internal mechanisms of the inner ear) to the inside of your mouth. They are the system for equalizing pressure between the sides of the eardrum, and also for draining any fluid accumulations. Like everything else, some people have better eustachian tube performance than others. Many people have such open tubes that nothing bothers them. They can experience substantial changes in altitude without noticing anything. (We call them fighter pilots.) Others are fine as long as they don't have a cold. A few have serious blockage. Children's tubes are especially narrow, so fluids can more easily collect and provide the media for the common ear infections of childhood. An otolaryngocolgist can perform a eustachian tube impedance test that will determine the condition of an adult's tubes. (I don't know what they do for children.) Children sometimes have tubes added to perforate their eardrums to relieve recurring pressure problems, as mentioned in earlier net.med postings. The pain from a pressure imbalance can be so great that sometimes the eardrum must be lanced (pierced with a sterile needle) to relieve the pressure. The very idea is frightening when you consider the delicate structures just behind the eardrum that can be damaged forever by excessive pressure or by an errant lance. And tubes in eardrums let in their own variety of contaminants; swimming may be difficult or forbidden. You may hear popping sounds in various circumstances when a change in posture slightly changes the shape of the middle ear, causing a pressure change that relieves itself through the tubes. Also, over time the pressure changes in the middle ear by diffusion of gases or fluids through the tissues. These changes also need equalizing. There are also two muscles attached to the mechanical linkage between the eardrum and the cochlea. I think they are designed to limit the excursion of the linkage in case of very large amplitude sounds. If this is true, the limit system would introduce distortion and pressure sensations on the eardrum if it was triggered by sudden volume shifts. Remember that sound pressure follows the square law and a source 2 times closer is 4 times louder. As long as I'm on the subject, I'd like to emphasize a point about ears and airplanes. Be prepared to cancel a flight if you have a bad cold. I'm not going to describe the damage that excess pressure can cause, other than to say that it can be severe and permanent. I met a steward who told of flying with a cold and bleeding from an ear as a result. His casual attitude about it shocked me. In retrospect, I realized that the torn eardrum relieved the pain and prevented worse damage. I guess he wasn't concerned about the longer term effects on his hearing. The standard maximum cabin altitude for commercial jet airplanes is 8000 feet. Not every flight goes this high (1/2 hour hops frequently stay at local altitude), but the typical range is 5500-7000 feet. (Letting pressure out of the plane reduces the metal fatigue rate.) This is a large pressure difference from sea level. (Check the tension on the seal of a little cup of cream or salad dressing that was packed on the ground.) Once, when a stewardess was checking the cabin altitude for me, she told me that a pilot may under-report the altitude if he thinks she's complaining about being tired because of the high altitude. Pressure flows out of the eustachian tubes much more easily than it goes in, so you might not notice a problem at the beginning of the flight. But on descent, if you have any restrictions, you must help the tubes stay open. First of all, avoid alchoholic beverages, especially wine. Wine contains something that releases histamines in the body, causing general tissue swelling, including in the eustachian tubes. Next, be awake when descent begins. If you're asleep, not only are you unable to help keep your tubes open, but you may be in a position that helps to keep them closed. Ask someone to wake you 45 minutes before arrival. The flight engineer turns a rate control knob to start the repressurization of the cabin at the start of descent. Descent usually begins 1/2 hour before arrival; if you know when that is, you can usually tell that it has begun because the engines change their sound, the plane tilts forward slightly, and you feel pressure in your ears. Now, make sure that your ears equalize regularly during the descent. If you wait until you feel a lot of pressure, the eustachian tubes may begin to collapse under the pressure and you will have to work much harder to re-open them. Keep equalizing every few minutes. The usual descent rate is around 200-400 (cabin altitude) feet per minute. The pressure changes end when the plane is 2000-5000 feet above the runway. The cabin altitude is now approximately at the runway level. If you are in a holding pattern, the pressure will remain constant at that level. The last change occurs at 500 feet above the runway, when the cabin is vented to the outside to eliminate any remaining pressure difference. People use many techniques to equalize, including chewing gum, blowing their noses, yawning. If you are starting out with a cold or other congestion, be sure to use decongestants and/or nose spray. Remember that ascent is fairly easy to equalize, so take the decongestant an hour or so before descent to ensure that it is effective during descent. One test to decide if decongestants will help is to blow your nose while still on the ground. If you are so blocked up that you can't feel anything in your ears when you blow, you probably shouldn't fly that day. Decongestants have a way of leaving you more stuffed when they wear off, and you get tolerant of them quickly too, so don't overuse them. This information comes from an article "The Newest Fear of Flying: Ear Damage" in New York Magazine in 1979 (I found it in a reprint by a hearing aid company), from Gray's Anatomy, from general sources including doctors and the net, from conversations with pilots, and from my own observations of cabin pressures using an altimeter. Glenn Axelrod Maynard, Mass