Every sound we hear—birds chirping, bees buzzing—is a wave of pressure moving through the air, which our outer ears “catch” and funnel through the ear canal to be interpreted by the brain. When you speak, your ear is stimulated by internal vibrations from your vocal cords and by the sound coming out of your mouth and traveling through the air and into the ears. This combination gives your voice (as you hear it) a fuller, deeper quality that’s lacking when you hear it on a recording.—Matt Soniak, from Mental Floss