The Magic of Hearing
Have you ever wondered what makes hearing work? It’s actually quite a complicated process involving several different kinds of body parts. Here’s a quick description of how they all work together so that you can hear what’s going on around you.
The ear has three main parts (see Figure 1):
- The outer ear
- The middle ear
- The inner ear
Figure 1. Anatomy of the ear
As you can see in Figure 1, the outer ear opens into the ear canal. The eardrum (tympanum) separates the ear canal from the middle ear. The middle ear contains three small bones that help amplify the sound and transfer it to the inner ear. These three bones (ossicles), are the malleus, the inus, and the stapes. They are also referred to as the hammer, the anvil, and the stirrup because of their shapes.
The inner ear contains the cochlea, which changes sound into neurological signals, and the cochlear nerve, which takes sound to the brain.
Here’s how it all works together (see Figure 2).
- Any source of sound sends vibrations, called sound waves, into the air; these sound waves funnel into the ear opening, flow down the external ear canal, and strike your eardrum, causing it to vibrate
- The vibrations are passed from your eardrum to the three small bones of the middle ear
- One of these bones, the Stapes, is attached to the membrane of the oval window; vibrations transferred to the oval window create fluid waves in the cochlea
- The fluid waves push on the flexible membranes of the cochlear duct; hair cells bend and chemical channels open, creating an electrical signal
- These nerve impulses are picked up by the cochlear nerve and delivered to the brain, where they are interpreted (music, voice, car horn, water, wind, etc.); you recognize the sound based on how your brain interprets the auditory nerve signals
- Excess energy from the fluid waves is transferred into the tympanic duct and sent back to the middle ear
Figure 2. How sound waves move through the ear
It all seems like a Rube Goldberg kind of contraption, but it works. And it works very well. But you can see that an interruption of the normal process at any stage along the way can interfere with your ability to hear properly. That’s why it’s important to take care of your ears and seek professional help if you think there is a problem. In most cases, the sooner you recognize a problem, the more likely it can be resolved.
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