I like using my earbuds when in the airplane, since they provide better sound insulation than the standard economy headphones, but I've been told (I couldn't find any information confirming it though) that they might by a hazard in case of depressurization.
Admittedly, this is extremely rare, but still, could it happen that in this case they might get "sucked" into the ear and possibly damage the eardrum? Or can I travel safe wearing my eardrums all along the flight?
They are not going to be 'sucked in'. Pressure increase in the cabin (causing inward pressure) happens fairly gradually as the plane descends. Even in an uncontrolled dive, it will take awhile for a plane to go from cruising altitude (30.000 feet or so) to 8.000 feet at which point the outside and inside pressure is about equal.
The only possible rapid change in cabin pressure (that you will hopefully never experience) is a drop in pressure (decompression). This will cause the earbuds to be expelled from your ears (assuming the pressure differential is large enough to overcome the friction between the earbuds and your ear canal) because the outside pressure will now be lower than within your ear canal and thus the inside pressure will seek to normalize by expanding.
So you have nothing to worry about.
While it won't be a problem on de-pressurization, you should really think twice about using your own earphones on an aeroplane. The aeroplane usually has a 2-pin headphone socket, you can use your own headphones by plugging into the larger pin (which is 3.5mm). Unfortunately, the impedance of inflight headphones (300 ohm) is different to normal audioplayers (40 ohm) so it can "blow out" the tiny speakers in your headphones (reference).
This happened to me on Air India last week (and I've had to trash a £250 pair of B&W headphones). If you're using your own equipment, please make sure to use (what I previously considered) a pointless adaptor - it creates an impedance buffer and may save your equipment.
