When I stepped outside this morning, I heard the loud calling of a Carolina wren. In spite of the fact, I was some distance from the bird; the sounds it made were extremely loud. I can only imagine how loud they sounded to the calling wren. There are several reasons why loud vocalizations do not damage a bird’s ear.
To begin with, a bird’s ear is different from the human ear. For example, we have an outer, middle and inner ear. Birds, on the other hand, lack an outer ear structure. However, small feathers called auriculars protect the opening into ear. These specialized feathers offer protection for the inner ear.
Most birds sing with their mouths open. As such, when like the Carolina wren opens its mouth to call, the canal leading to the middle ear automatically closes. When this happens the air pressure increases in the middle ear. This, in turn, diminishes sound vibrations. In addition, the movement of the jawbone eases the tension on the eardrum.
Since we do not possess these adaptations, the only way we can protect ourselves from loud sounds is to wear proper ear protection devices.
In addition, when we damage the hair cells in our ears, we cannot repair them. Such is not the case with birds; they simply grow new hair cells that restore their ability to hear.
This is just another amazing example of how birds so well adapted to their environment.