I just pulled apart an old set of headphones that had stopped working on one channel. I managed to fix the wiring, but I ripped up the foam lining inside the cups while getting it apart. I'm not talking about the ear cushions, I'm talking about a thin foam lining that goes between the drivers and the ear cups. In my headphones it's just plastic with lots of holes in it between the driver and the cup space where your ears go. Then this thin foam lining over the top of this plastic next to the ears.Well now that those foam linings have been damaged I've removed them from both cups and to be honest I can't notice any difference in how they sound. So I'm just wondering if that foam is supposed to have any sonic function, or is it just for comfort?