concha

3.17  concha. A depression in the external ear surrounding the meatus bounded in front by the tragus (3.69) and above, to the rear and below by cartilaginous ridges. It and the boundary ridges contribute to sound source direction and location. It also aids fitting and retention of ear molds in the meatus.

Annotation            Of the visible and identified anatomical features of the pinna, the concha and tragus together are acoustically its most important features because of their shape, dimensions and location relative to and surrounding the entrance to the ear canal.