Hearing and Balance ( ESSAY )

Let's start today with several questions.

• What is sound?
• How can I hear the sound?
• How can I walk around without falling on my face?

I'll start off by answering the first question. The basic and short answer to the question of "what is sound" is : 'Sounds create vibrations in the air that beat against the eardrum, which pushes on a series of tiny bones called "auditory ossicles" that move internal fluid against a membrane that triggers tiny hair cells -- which aren't actually hairs -- that stimulate neurons, which in turn send action potentials to the brain, which interpret them as sound.' Short and simple, right? But there is a lot more going on in our ear to just allowing us to hear a beautiful song, it also allows you to stand up, walk, and even dance. Yes, the ear also houses the part of your body that allows you to keep your balance. To better understand how your ears pick up sound, we must first understand how sound actually works. The key to sound transmission is vibration. When I talk, my vocal folds vibrate, creating sound. When I slam this desk I'm writing on, or strum a guitar, those vibrations cause air particles to vibrate too, initiating sound waves that carry the vibrations through the air. To hear a sound, your ear must then pick up that vibration that was travelling through the air, and then send it to your brain that then process it, then, and only then, can you finally hear the sounds. One more thing. You may say, "well they all vibrate, what then makes their sound different?" The difference is in the shape of the sound waves and their frequency. Frequency is the number of waves that pass a certain point at a given time frame. A high-pitched noise is the result of shorter waves moving in and out more quickly, while fewer, slower fluctuations, result in a lower pitch. That is for how high or low the notes are, but for loudness, it depends on the waves' amplitude, or the difference between the high and low pressures created in the air by that sound wave. Now, in order for you to pick up and identify barking or beeping, or any sound at all, the sound waves have to reach the part of the ear where those frequencies and air-pressure fluctuations can register and be understand by the brain. Now let's get to the anatomy of the ear. The ear are divided into three major areas : the external, middle, and inner ear. The external and middle ear are only involved in hearing, but your inner ear is key to both hearing and maintaining your balance, or equilibrium. So the pinna, or auricle, is the part that you can see, and wiggle, or grab, or festoon with an earing. It's made up of elastic cartilage covered in skin, and it's main function is to catch sound waves, and pass them along deeper into the ear. Once a sound is "caught" it is funneled down into the external acoustic meatus, or auditory canal, and toward your middle and inner ear. Sound waves traveling down the auditory canal eventually collide with the tympanic membrane, which you probably better known as the eardrum. This ultra-sensitive, translucent, and slightly cone shaped membrane of connective tissue is the boundary between the external and middle ear. When those sound waves collide with the eardrum, they push it back and forth, making it vibrate so it can pass those vibrations along to the tiny bones located in the middle ear. Now the middle ear, also known as the tympanic cavity, is the relay station between the external and inner ear. It's main job is to amplify things a little bit, so that they are louder when they enter the inner ear. And it needs to amplify those sound waves, because the inner ear is located inside a special fluid, and as you probably already know, that it is more hard to move through a liquid than through a vacuum. The tympanic cavity focuses the pressure of sound waves so that they're strong enough to move the fluid in the inner ear. And it does this by the help of the auditory ossicles -- a trio of the smallest bones in your whole body : the malleus, incus, and stapes, commonly known as the hammer, anvil, and stirrup. One end of the malleus connects to the inner eardrum and moves back and forth when the drum vibrates. The other end is attached to the incus, which is also connected to the stapes. Together they form a kind of chain that conducts eardrum vibrations over to another membrane, the superior oval window, where they set those fluid in the inner ear into motion. Your inner ear is mysterious, complicated, and also interesting. It has some of the most complicated anatomy of your entire body, and don't worry, it is planted deep down in your head, so it's more or less, safe. It's other name : the labyrinth. It has two very important jobs to do : to turn those vibrations into electrical impulses that the brain can understand; and also help maintain your balance, or equilibrium, so that you are always aware which way is up or down and stuff. The labyrinth actually has two layers : the bony labyrinth, and the membranous labyrinth. The bony labyrinth is a big fluid-filled system of wavy wormholes. while the membranous labyrinth is a continuous series of sacs and ducts inside the bony labyrinth that basically follow the bony labyrinth's shape. Now the hearing function of the inner ear is housed in the cochlea, which has a back-of-a-snail-like structure. But the maintaining-your-equilibrium stuff is housed in the vestibular apparatus. Inside the vestibular apparatus, there is fluid that is controlled by the movement of your head. This structure has three semi-circles which all sit in the sagittal, frontal, and transverse planes. Based on the movement of the fluid inside of them, those three semicircular arches can detect movement of your head from vertically, horizontally, and in between those. So there you go. An essay on your ear, hearing, and how you can keep your balance, or equilibrium.