—Alyssa Dare, Elkridge, Maryland As many of us know, sound is a vibration that propagates as a wave through a medium. In general, sound travels slowest through gases (such as air), faster through liquids and fastest through solids. So no matter how well you block your outer ears, sound waves will still travel effectively through your head, where they will easily reach your middle and inner ears. You can even buy bone conduction headphones, which bypass your outer ears entirely. Bone conduction hearing technology has been in use for decades, including in the military, although it is not well known among the general public.
