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Science Series Part 7: The Ear Canal

Dr. Emily Martinson, AuD, PhD

After a lengthy break discussing much more interesting topics, today we return to the world of science!  Grab your pocket protector and cancel that prom date, it’s nerd time!

Today we move on to the next portion of the hearing system: the ear canal.  Recall from our last Science Series discussion that the ear is made of three parts: the outer ear, the middle ear, and the inner ear.  The outer ear is composed of the pinna (the most visible portion of the ear), the ear canal, and part of the ear drum.  Our last discussion was on the pinna, bringing us to our focus today: the ear canal.

The ear canal serves three main purposes: producing earwax, bringing sound from the outside world to the eardrum, and amplifying that sound.  Let’s start with producing earwax.

As discussed in last week’s post, earwax is an important protective mechanism for the ear canal.  Earwax is made of secretions from wax glands and sweat glands, and has antibacterial properties.  Interestingly, the skin on the ear canal grows outward, which naturally moves the earwax out of the ear to keep the ear canal clean.

The second purpose of the ear canal is to bring sound from the outside world to the eardrum.  Imagine the ear canal like a Pringles container, where one end (the outermost part) is open, and the other end is closed (the eardrum).  As a side note, putting Pringles in your ear canal is strongly discouraged.

The final purpose of the ear canal is to amplify sound, which is (in my nerdy opinion) the coolest part.  The opening of the ear canal is slightly larger than the end with the eardrum.  Imagine the ear canal shaped like a funnel, with the large end at the beginning and the small end at the eardrum.

Recall from past Science Series discussions that sound waves vibrate with varying levels of intensity.  The more intense the sound wave, the louder the sound.  Much like a funnel, the sound pressure (or water flow in this example) is much higher and concentrated at the end.  In the ear canal, sound is more intense at the level of the eardrum than the outer portion, making it easier for you to hear.