To get a better grasp of tinnitus, how it comes about, and what can be done about it, it helps to understand something about how our sense of hearing works. This article is the second of a three article series that deals with tinnitus and the three major parts of the human ear, the outer ear, the middle ear, and the inner ear. This second part focuses on the middle ear, how it works, what can go wrong to engender tinnitus, and what can be done to resolve it. Now, let's look at the middle ear.
The middle ear begins right where the outer ear ends, with the tympanic membrane. The eardrum is the dividing membrane separating the outer and middle ear. The outer surface of the eardrum is considered part of the outer ear, while the inner surface of the eardrum is part of the middle ear.
As sound waves travel through the outer ear the energy quickly hits what we commonly call the ear drum. This tiny membrane, the tympanic membrane, is constantly responding to air pressure fluctuations in the atmosphere around us. When a sound wave moves through the ear canal and strikes the tympanic membrane, a chain reaction is set in motion, which is a purely mechanical reaction.
Being a specialized, taut skin membrane, the ear drum vibrates back and forth in response to the energy of the sound wave, according to the qualities of the sound, such as pitch and volume. The vibrations move quickly for the shorter waves of high-pitch sounds, and more slowly for the longer waves of low-pitch sounds. The energy of a loud sound will impress the eardrum more deeply, while the softest detectable sound of a healthy young adult moves the membrane only about 1 millionth of an inch Truly a marvel!
The tympanic membrane begins the process of changing sound waves into the form that the brain can interpret. Usually the ear receives more than one sound at once. Imagine sitting in a restaurant conversing with your friend. The eardrum helps you to focus and concentrate on what your friend is saying, while putting all of the other sounds of the restaurant in the background.
To a certain degree, the ear drum can also help prevent damage to the inner ear from very loud sounds. The tympanic muscle contracts in reaction to very loud sounds, and does not vibrate normally. The amount of sound energy that gets beyond the tympanic membrane is thereby reduced. However, that mechanism cannot protect us from all excessively loud sounds, so we do have to take responsibility for protecting ourselves from sounds that can cause hearing damage.
Our modern, industrial world produces sound volumes that are not experienced by pre-industrial peoples. Our ears and hearing have not had the time needed to adapt or evolve enough to protect us from the damage caused by the sounds we now experience in our modern world. Whether it is the screaming of jet engines at an airport, or the high decibel speakers of a night club, such loud sounds or noises are well-known as one of the primary causes of hearing loss and tinnitus today.
As wonderful as our eardrums might be, they have evolved to shield us from the loud sounds produced by nature itself, not the powerful sound waves generated by today's high-charged music amplifiers. Therefore, we have responsibility for protecting our ears from the excessively loud sounds of today.
Having said that, let's move on inside the middle ear. Up to this point, we have traced the movement of sound waves through the air, then gathered by the pinna, funneled through the auditory canal, at the end of which the sound energy caused the eardrum to vibrate. From there the middle ear functions to amplify the sound, so that when it is transferred to the inner ear, which is fluid filled, the sound will carry properly through the denser medium. Because the inner ear is fluid-filled rather than air filled, and a denser medium by nature, the amplification that the middle ear performs is really necessary. Our appreciation for how our hearing works can only increase as we understand how the middle ear carries out that amplification and focus.
The primary components within the usually dry chamber of the middle ear are called ossicles. The literal meaning of the word ossicle is "tiny bone," and the ossicles are indeed the three smallest bones found in the human body. The sound vibrations of the eardrum are transferred directly to the malleus, the first of the three ossicles, which is attached directly to the eardrum. With falling domino like action, the malleus then strikes the next ossicle, called the incus, transferring the energy. The sound energy is then transferred to the stapes, the third ossicle. Then the stapes, which is attached to the inner ear, transmits the sound energy to the cochlea of the inner ear.
It is an incredible mechanism, and mechanism is the right word for it, because our sense of hearing is a mechanical process, as opposed to our senses of sight and taste which involve chemical processes. Hearing is a mechanical operation.
Acting as a set of levers, the ossicles magnify the mechanical energy of the eardrum, concentrating the energy from the larger tympanic membrane to the smaller membrane of the oval window of the inner ear. As a result, the ossicles pass on amplified energy with greater concentration to the inner ear. As stated before, because the inner ear is fluid-filled and denser, the kick of amplification that the ossicles leverage is necessary for overcoming the greater inertia of the inner ear's medium. Is it not fantastic?
The final part of the middle ear that needs attention is the eustachian tube which connects the dry chamber of the ossicles with the throat. Those of us who have experienced a common head cold understand that the ears, nose, and throat share common connections. The eustachian tube provides the ear connection.
The eustachian tube keeps the air pressure on either side of the tympanic membrane equal. It is also a drain tube for the middle ear, to keep it free from fluid or congestion. In so doing it is also there to keep the middle ear free from infection.
If you have ever flown in a plane or driven in the mountains, you probably know the feeling of greater or lesser air pressure on either side of the eardrum. Maybe you yawned or made a chewing motion or swallowed, and heard a popping or clicking sound that was accompanied by a sense of relief. That was the eustacian tube functioning to keep the air pressure on either side of the eardrum equalized.
When tinnitus comes about in the middle ear, it is usually due to the eustachian tube becoming blocked by swelling, inflamed tissues from sinusitis, rhinitis, or an allergy bout. Excess fluid can be trapped within the middle ear, when the eustachian tube becomes blocked, forming an ideal breeding ground for bacteria or viruses, causing otitis media or inflammation or infection of the middle ear which can give rise to tinnitus symptoms. While proper treatment of the infection and inflammation usually resolves the ringing in ears, chronic sinusitis or allergies can lead to chronic tinnitus. In that case, a good holistic tinnitus treatment regimen offers the best chance for a permanent tinnitus cure.
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