The pinna is the visible part of the ear that resides outside of the head. We often use the pinna, also called the auricle, for hanging earrings and resting eyeglasses, but the evolutionary purpose of the pinna is to collect sound. It does so by acting as a funnel, amplifying the sound and directing it to the ear canal. While passing through the pinna, sound also goes through a filtering process which adds directional information to the sound (see sound localization, head-related transfer function, pinna notch ). Notably, the filtering of the human pinna also selects for sounds in the frequency range of human speech.
