While I'm taking off the headphone, my glasses were taken off accidentally, and their hinge frames on the both side have put against the inside of the ear cup. The clamping force sustained the glasses on the air for a moment.
The spot was somewhere around the red-colored. I went ahead and took out the earpads to check the possible damage inside, but I saw nothing particular.
Right now, I'm going paranoia, and every sometimes I think I hear strange noises.
My question is:
the red-colored part in the second image, is it vulnerable? 'though I see no visible damage.. I'm really worried.
If i was in this situation I would generate and listen to a tone sweep on the headphones at medium to high volumes. if you hear any distortion on the left or right ear then flip the headphones around and see if the other ear can hear it, if you can then you may have caused some borkage.
Great idea! Thank you! Maybe it's okay since I don't hear anything particular.
The parts you encircled are just a mesh (I don't know exactly what purpose they serve, perhaps to tone down reflections). Below the hole in the middle and this mesh is the fragile part, the membrane of the driver. In any case, you can replace the whole part, to my knowledge Sennheiser still offers those as spare parts.
No problems at all there, they're still fine. No need to worry.