An earplug comprises a core and a sound-attenuating body attached to the core, the sound-attenuating body comprising a tip cavity extending proximally from the tip of the sound-attenuating body and comprising a distal opening. The tip cavity side wall includes a plurality of protrusions extending inwardly toward the longitudinal axis of the core. The plurality of protrusions may include from 2 to 12 protrusions. A method of making an earplug includes covering at least a portion of a core with a material including unactivated foaming agent; inserting an end of the core and at least a portion of the material into a mold cavity; and activating the foaming agent to create a sound-attenuating body. The sound-attenuating body has a base, tip, and tip cavity with a plurality of protrusions. The mold cavity may include a boss with a cup and plurality of cut-outs on the cup for forming the protrusions.