For the last several days, I've been studying a tutorial by Stan Prokopenko on "How to Draw Ears." My ATC's for May 2012 were my practices sessions using markers, water colors, pen and ink. See blog post dated 5/19/2012.
This is the final "photoshopped drawing" I made before I started working on the "25 yEARS" series. I used a picture of my husband's ear using the "photocopy" filter so that I could see the outlines of the ear structure. I visited many images of ear anatomy using Google Image search. The process of learning ear anatomy made it easier to "see" what I was trying to draw in terms of the three-dimensional nature of the external ear.