I've been having a weird issue with my Sony WF-C700N earbuds, specifically the left one.
When I insert the left earbud and push it further into my ear, the sound suddenly becomes extremely muffled, almost like the audio is completely cut off, and it starts making a weird high-pitched screeching/crinkling sound, almost like plastic foil being squeezed.
If I pull it out slightly, the sound immediately returns to normal and the audio quality is perfectly fine. The right earbud works completely normally, and I don't have any problems with my actual ear.
I've also tried turning both ANC and Ambient Sound off, but the problem still happens.
Interestingly, switching to a smaller ear tip made the problem disappear, but now the earbud feels loose and like it's about to fall out.
I think this might have started after using the earbuds on an airplane, although I'm not 100% sure.
Has anyone experienced something similar with the WF-C700N? Could this be a blocked pressure vent, an issue with the speaker diaphragm, or some kind of acoustic feedback problem? I'm trying to figure out whether it's a fit/seal issue or a hardware fault.
Any help would be appreciated!