Tuesday, 08 January 2008 19:15
Hi Capt Lim,
When an aircraft is descending, I always get a strange hissing feeling in my ears . Why is it so when I don't get this during the take off and climb?
I have answered a similar question previously but in slightly different circumstances. Well, to repeat the answer with a bit of variation; Do you know that, as the airplane climbs to its cruising altitude, the cabin pressure is decreasing gradually? So that creates a differential pressure between any airs trapped in your body and those of the cabin. If you are fit and healthy, without any cold symptoms, you may not feel the change of air pressure during the take off and climb because the air leaks out very slowly through the Eustachian tube that connects your middle ear to your mouth and nose.
If you were to look at the diagram of the Eustachian tube, you would find that it is easier for air to leak out from the middle ear like a balloon. However, if you have a slight cold, the tube membrane at the hole may be wet, swollen or partly blocked. This tends to close the little hole and make it more difficult for air to flow in a reverse direction during the descent. The pressure outside the so-called balloon is greater now and hence, in trying to equalize, it wants to flow back, but with difficulty because it is partially closed by the wet membrane. So the intermittent opening of the hole to equalize the pressure would cause a popping or hissing sound in your ears. A severe cold would aggravate the condition for it can totally rupture your eardrum. Hence the advice, do not fly when you have a severe cold!
What to do if you find discomfort in clearing your ears during the descent? Move your jaws from side to side or swallow repeatedly to exercise the muscle so as to clear the Eustachian tube. If that still fails, try holding your nose closed and blow moderately till you hear a popping sound, indicating that the channel is cleared. This technique is also known as the Valsalva maneuver.
Wish you a hissing-less flight the next time!