yeh been suffering by something alike a lot for a couple of months by now, fortunately it's gradually disappearing and i'm almost back to normal (gosh, i already forgot what's normal so cant be sure ;)
my left ear just got blocked by no apparent reason, starting small but progressing quick to a complete closure, followed by the right one getting obstructed to a certainly irritating degree as well. i could barely hear at some point except my own (annoying) voice from the inside and all those hardcore noises resembling an industrial nightmare orchestra //
went to two different docs, both told me it's otitis externa and prescribed useless antibiotics despite me pointing out the unlikely symptoms -- so i took on a little research on my own and found out it must be the mystical "eustachian tube" who's at guilt.
tube's purpose is to equalize the internal pressure with that on the outer side of the eardrum by letting the air in when necessary and remaining closed otherwise -- however one can "open" it a little by yawning as well as few other tricks.
to cut it short: the tube may easily get locked by a common cold just like your nose does -- especially if you try hard to blow the stuff out. and if you're unfortunate enough, an infection may occur causing an ear blockage which outlives the cold by far. once the pressure in the middle ear is out of balance, the eardrum becomes somehow rigid causing a partial deafness and the "funny" noises is nothing more than a forceful equalization of the pressure -- imagine an air breaking thru your swollen liquid-filled tube ;)
looks like a pretty believable theory to me, aight!