I just got a set of the EP4 in-ear plugs. I like them, but am wondering if I should have gotten the EP3's instead. When installed, the EP4's muffle all noise, with the caps off. I assume that it is due to the small opening and the sound waves bouncing off the rubber, but am also wondering if they are getting mashed in my ear canal. The EP3's apparently only use 2 cups, as opposed to the EP4's 3 cups. So, is muffled sound at all levels normal for the EP4's, or should I get the 3's? TIA.