The Outer Ear
Studies on the Human Ear

The Outer Ear

The outer ear consists of the external ear, the opening of the ear, or concha, and the auditory canal.

The external ear, or visible ear, known medically as the pinna or auricle, is attached to the outside wall of the skull, with its center positioned midpoint between the top of the head and the chin on the vertical axis, and the eye and the nose of the face on the horizontal axis.

The external ear is oval-shaped, and consists of a concave flap of skin and cartilage that extends inward toward a small opening at the side of the head. The outer surface of the ear contains ridges, curves, and crevices which differ from person to person. The irregularities on the ear's surface help to locate the position of a sound source in space.

At the base of the temple along the lower inside edge of the ear, just above the earlobe, is a small piece of cartilage that juts out toward the opening of the ear, known as the tragis. This small tab of cartilage is positioned to block foreign objects from entering the ear, such as debris which might accompany a gust of wind blowing across our face.

In addition, the tragis appears to prevent sound frequencies from entering the ear from the side of the head. This effects the time delay in which the sound enters both ears, which is useful in locating the position of a sound source.

Along most of the outside rim of the ear is a narrow fold of tissue known as the flange or helix. This outer ridge of the ear is designed to collect sounds and project them into the ear canal.

Located at the boundary between the edge of the face and the visible ear, just below the helix, is the earlobe. The earlobe is a mass of fleshy skin and tissue which extends downward toward the chin. A small percentage of the human population are missing earlobes, which is typically a genetic trait.

There is a small bowl-shaped opening at the entrance to the ear canal, known as the concha. The shape of this opening helps to direct the sound into the auditory canal.

In general, the function of the external ear is to trap sound waves traveling through the air, and to direct them through the auditory canal toward the eardrum.

The auditory canal is a thin tube which originates from the opening in the external ear. The tube is about one inch long, and forms a narrow passage that terminates at the eardrum.

The part of the ear canal nearest the entrance is made of cartilage. The cartilage is covered with skin that produces wax, which along with hair follicles prevent dust and small objects from entering the ear.

In addition, the auditory canal functions as a resonant tube that amplifies the sound waves so that they create a sufficient amount of energy to stimulate the eardrum.

Working together, the external ear and the auditory canal modify the sounds which enter the ear by selecting certain frequencies that are associated with human speech, and by amplifying sounds. Furthermore, the texture of the visible ear, as well as the position of the ears on the head, are used to pinpoint the direction of a sound source.