Dr. Emily Martinson, Au.D., Ph.D.
Now that we’ve defined sound and discussed various properties of the sound wave, we can talk about the ear itself and how the shape of the ear helps us to hear. The ear is made of three parts: the outer ear, middle ear, and inner ear. As they say in The Sound of Music, let’s start from the very beginning.
The outer ear is made of two parts: the pinna and the ear canal. The pinna, along with The Nina and The Santa Maria, was one of Columbus’s ships. Just kidding, the pinna is the large round outer part that we can see when we look at someone’s ear, and the ear canal is a tunnel leading to the eardrum (more on the ear canal next time). Today we will focus on the pinna.
The shape of the pinna is very important, and does more than just hold up your glasses and hearing aids. The pinna sticks out (for some of us more than others!) to capture the sound. Think about a rabbit when it tries to hear. The rabbit moves its ears towards the source of sound to hear better, and can turn its pinna towards the sound source to try and locate it.
If you put your hands behind your ears and make artificial rabbit ears, you hear better right away. In the same way, the pinna of the outer ear helps you to hear better. People who are born without a pinna or lose theirs in an accident have a reduction in their hearing.
Think about that next time you put on your glasses!