Well after some comparison flight tests I find that the A-11 (and AN-H-15 for that matter) rubber earcups do not block cabin noise as well as a decent set of passive noise reduction headphones.

So my next experiment is to remove the rubber earcup/receiver holders from an AN-H-15 and replace it with plastic oval earcups that are roughly the same size and shape.

My question is this:

Is there any sound absorption material places inside the plastic "cans" of modern headsets? I don'e mean the earseal, but, rather, between the speaker and the plastic can the seals are mounted to.

Thanks!