Introduction to Hearing

My previous posts have discussed the physical nature of sound by looking at sound waves. While I have researched the physical properties of sound waves that dictate the timbre and pitch of instruments, I have not yet addressed how we as humans are able to perceive these differences. While there is a lot of knowledge about the neurological processes that allow us to hear, there is still much to learn.

Humans perceive sound through the use of two things: the ear and the brain. The ear is like a sensor. It collects the different sound waves passing through the air, and then converts them into information that the brain can understand. The actual perception of sound then occurs in the brain. The ear is a very complex piece of anatomy: in order to turn sound waves into nerve signals, it utilizes many different components. This is a nice diagram showing the parts of the inner ear:

(The Physics of Music and Color)

Future posts will go into specific details about some of these individual components, but for now it is important to grasp just how complicated the ear is. It must be able to detect different frequencies of sound waves - this is what allows us to distinguish sounds by pitch. In fact, most people can usually perceive sounds from 20-20,000 hz, but the upper limit decreases with age.  The ear also must be able to process different wave shapes - this is what allows us to distinguish the timbre of sound and differentiate different musical instruments. It also must be able to perceive the amplitude of sound waves - this is what allows us to distinguish sound by volume. All of these different processes are accounted for by the different components of the inner ear in interesting ways.

Works Cited:

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