• Your Ear—The Great Communicator
    Awake!—1990 | January 22

    • Outer Ear​—The Tuned Receiver

      Obviously, the external ear serves to collect sound waves in the air and channel them to the inner parts of the ear. But it does much more than that.

      Have you ever wondered if the convoluted shape of the external ear serves any specific purpose? Scientists find that the cavity at the center of the external ear and the ear canal are so shaped that they enhance sounds, or resonate, within a certain frequency range. How does that benefit us? It so happens that most of the important characteristics of human speech sounds fall in about the same range.a As these sounds travel through the external ear and the ear canal, they are boosted to about twice their original intensity. This is acoustical engineering of the highest order!

      The outer ear also plays an important role in our ability to locate the source of sound. As mentioned, sounds coming from the left or right of the head are identified by the difference in intensity and arrival time at the two ears. But what about sounds that come from behind? Again, the shape of the ear comes into play. The edge of our ear is shaped in such a way that it interacts with sounds coming from behind, causing a loss in the 3,000- to 6,000-​Hz range. This alters the character of the sound, and the brain interprets it as coming from behind. Sounds from above the head are also altered but in a different frequency band.