Have you ever conducted a private survey of the human ear? It is a fascinating experience. It's an interesting way to pass the time while waiting for your appointment in a doctor's office, or for your mate to finish some shopping, or for a plane to arrive at the terminal, or if you are sitting in a meeting that begins to drag.

This exercise is more a comparison than a survey. It involves looking carefully at human ears to see their differences in size and shape, and in the ways they are attached to the head. You'll discover that some ears are large and some small, some protrude and some lie flat against the head. You will note that some ears have glasses hooked across them, some have hearing aids in them, some are pierced, and others have ornaments hanging from them.

The obvious function of …