Good question. It’s because I was afraid of the possible effect of uneven pressure on both sides of the eardrum, which could dampen its vibration.
However, it’s possible that it isn’t that scary, because even with a workaround of packing the vent with tissue paper, I don’t feel that phenomenon.
So, I’ll see tomorrow the cShell for spare Paradise 90 with 0.6mm vent (I hope), and in the next few days I’ll make a decision if it would be better with no vent for as narrow and deeply placed cShell as possible, because there will be no space needed for vent canal.
There was another topic: