The Auditory Canal and the Eardrum

In order to begin my study of the human perception of sound, I began by researching the auditory canal and eardrum, which are arguably the two most important components of the ear. For reference, here is the diagram from my initial post that details the parts of the ear:

(The Physics of Music and Color)

The auditory canal is the tube within the ear that connects the outer ear to the eardrum and middle ear. Its purpose is bring the vibration of air particles, or sound waves, from the outside air to the inner parts of the ear that can interpret them. Interestingly, the auditory canal behaves like a tube that is open at one end, something I explored in a previous experiment. This causes it to resonate at certain frequencies that are dependent its length and diameter. They are approximately 3,000, 9,000, and 16,000 hertz (The Physics of Music and Color). This emphasizes certain frequencies, which alters how our perception of sound differs from the reality of sound, but this topic will get its own blog post in the future. The shape of the auditory canal is useful for another reason in that it is able to prevent some of the reflection of sound that naturally occurs within the ear; this allows the ear to maximize the amount of sound humans can perceive.

The eardrum is the first part of the ear that sound waves come into contact with after passing through the auditory canal, which makes it incredibly important. The eardrum effectively measures differences between pressure within the ear and pressure outside of the ear. Differences in pressure cause the eardrum to vibrate, and the eardrum sends this energy to the other parts of the ear to be interpreted. It is a very small and delicate membrane; these characteristics allow it to vibrate more easily and to be sensitive, which helps us to perceive quiet sounds.

Works Cited:

1.  Gunther, Leon. The Physics of Music and Color. New York, New York: Springer, 2012.