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Hearing Loss and Deafness

Language defines us as humans. Hearing is how we learn speech. As we learn our language as children, we use that language to organize how we see the world. Hearing is how we best receive the speech sounds that contain the ideas, feelings, and personalities of other humans.

If we lose hearing, we lose a bit of our humanity. The device we call the ear performs the task of translating the analog sound waves in the air into digitized nerve impulses in the organ of hearing. The process of hearing involves two principal stages. First, the sound waves traveling in the air are reproduced in the fluids of the cochlear portion of the inner ear. The structures which accomplish this task include the outer ear, the ear passage, and the eardrum and bony chain. The next phase of hearing involves the hair cell array in the organ of Corti of the cochlea, which analyses the waves and converts them into the complex digital code carried by the nerve of hearing to the brain. Additional stages of hearing include the brain which constantly adjusts the cochlea depending on what we intend to hear. Our ears exhibit miraculous sensitivity.
Disorders of the ear may affect either or both stages. The two overall types of loss are: conductive.......caused by problems affecting the first stage of sound processing nerve loss.........resulting from malfunctions in the second and later stages.

SENSITIVITY - INNER EAR SENSITIVITIES

The conduction mechanism of the first stage, at the threshold of hearing for a 1000 Hz tone moves a distance of 1/10th the diameter of a hydrogen atom. We perceive the movement as sound.
Mode Lowest Reported Threshold
Auditory 10-4 dyn/cm2 peak sound pressure
Seismic 5 X 10-4 cm/sec2 peak acceleration
Rotational 0.04 deg/sec peak velocity
Gravity 5 cm/sec2 lineal acceleration

CONDUCTIVE LOSSES

Conductive losses are caused by anything interfering with the first stage of sound processing. Conductive losses make the sounds seem faint or distant. When the sound source is made louder, the hearing loss is completely overcome. Often the hearing loss is accompanied by a feeling of blockage.
Common causes include wax in the outer ear passage or fluid in the middle ear.
Other conditions include otosclerosis which jams the bony linkage between the eardrum and the inner ear, or eardrum/bony chain damage from chronic infection.
Conductive losses almost always can be repaired by either medicine, surgery, or a combination.

WAX IN THE OUTER EAR PASSAGE - OTITUS EXTERNA

Otitis externa has many different names depending on the stage of the disease. Some call it swimmer's ear. Others refer to a "fungus" in their ears. The most closely related condition anywhere else in the body is eczema.

This condition usually starts when the natural wax barrier in the ear is damaged. Wax is a substance produced by the skin in the outer passage of the ear which protects the ear from moisture and bacteria. It is not a waste product. Sooner or later, all artificial attempts to remove wax damage the protection of the outer passage of the ear. This is why we are so opposed to using cotton-tipped applicators, hairpins, and other instruments as part of personal hygiene. The wax is formed within the ear and slides out the ear where the movement of the jaw joint crumbles the dried wax and allows it to flake out. Beyond the unsightly wax which appears at the very edge of the ear passage and which can be easily reached with a damp face cloth gently twirled on the finger, there is usually no visible wax in the rest of the ear passage.

The two major enemies of the waxy defense system in the outer ear passage are water and mechanical scratching or rubbing. Once the wax defenses are broken, certain bacteria begin to invade and create an alkaline environment which makes the ear weep and become itchy. Usually, this results in more scratching.

The first symptom of this condition is excess wax formation. This is a natural attempt by the ear to protect itself. Sooner or later, the wax glands become exhausted and the ear is super clean. It also itches. The irresistible urge to rub the ear now sets the ear up to be invaded by bacteria and it becomes moist and swollen. Finally, the repeated cycles of infection make the ear passage scar down and close.

The best way to avoid this disorder and the simplest way to reverse it once it begins is by avoiding anything that wets the ear or touches or rubs the inside of the ear. Wax should be removed only from the outermost edge of the ear passage. Cotton-tipped applicators will only push wax further down into the ear passage where it will accumulate and overload the transportation mechanism. Swimmers need only be sure that their ears are perfectly dry before retiring at night. Earplugs are not usually necessary and may even be undesirable. They push the wax further down inside the ear while at the same time providing a surface for the constantly moving ear passage to rub against. The best way to assure that the ear is dry is to use some form of drying drop which usually consists of some sort of mildly acetic substance. (Equal parts of rubbing alcohol and white vinegar can do as a drying drop in a pinch.) A hairdryer works well in drying the ear. Occasionally, oral antibiotics are required to control an acute flare-up. We like to avoid the use of any drops which are available on the market for dissolving ear wax since our experience has been that these drops have difficulty telling where the wax stops and your healthy ear passage begins.

If you find that you have a very hard wax, then a scheduled visit to the doctor is in order. Hydrogen peroxide is too watery to use more than rarely and should be used with specific doctor's instructions. It is helpful to use a few drops of mineral oil or baby oil at bedtime the night before the visit.

FLUID IN THE EAR (MIDDLE EAR VENTILATION PROBLEMS)

The ear passage is a tunnel at which end is a thin wall called the eardrum. On the other side of that eardrum is a space called the middle ear which normally contains air. The air gets there through a tube called the eustachian tube, which is normally closed, and which opens during yawning or swallowing, often causing a clicking sound. When the tube stops functioning, a vacuum develops in the ear. Nature responds to the vacuum by secreting fluid. The fluid may be as thin as water or so thick that we occasionally call it a glue ear. The degree of hearing loss caused by fluid varies. Occasionally, when there is a vacuum in the ear, the eardrum will be sucked in. When vacuum persists for years, chronic infection, damage to bone or perforations of the eardrum may result.

The tube that lets air into the ear is partially made out of a gristle (cartilage). In children, this cartilage is very soft and when a small vacuum develops in the ear, it tends to collapse the cartilage in the same way that a wet straw collapses when you try to drink through it. The cartilage firms up with maturity. Heredity seems to determine the mechanics of the muscles that serve to pull the tube open. Finally, there is a membrane factor, referred to as "allergy" which is poorly understood but is operating at a biochemical level. Children’s adenoids are said to have some mechanical effect on the way the tube opens, but their role in this process in quite unclear at this time.

Ear ventilation problems generally begin at about nine months of age, and gradually get worse until about six to eight years. By puberty, the ears improve, and most chronic ear ventilation problems have almost always vanished. In adults, the tubes malfunction during inflammatory conditions like infection or allergy. Those predisposed to such problems will experience the most difficulty when challenged by environmental pressure changes, such as flying or SCUBA diving.

Treatment varies. Decongestants are frequently offered to improve a borderline tube. Adenoidectomy is said to improve the mechanics of the eustachian tube opening. Artificial middle ear ventilating tubes break the vacuum in the ear responsible for the complications. Ear ventilating tubes mimic the solution nature sometimes uses...a hole in the eardrum. As long as the hole..natural or artificial..is kept perfectly dry, the ear will rarely get infected. Artificial tubes usually last about nine months, though the range can be from two weeks to two years!

NERVE HEARING LOSS

The structures involved in a nerve hearing loss (otherwise called ‘sensorineural’ or ‘perceptive’) include the cochlea and eighth cranial nerve, which are locked away inside the bones at the bottom of the skull. The sounds of language are coded in high frequencies and in low frequencies. When normal hearing people have difficulty hearing speech sounds in the low frequencies, they figure them out from what they hear in the high frequencies. In a noisy background, we count on both.

In addition to affecting the loudness of hearing, nerve hearing loss produces a distortion of the sounds entering the ear. Someone with this kind of loss may be aware of sounds but makes errors deciding exactly what sounds represent. People with nerve hearing loss experience difficulty decoding the complicated sounds we string together to make a speech.

In noisy situations, people with a nerve hearing loss - which almost always affects the high frequencies first - have the greatest difficulty.

Until recently, most of these losses were attributed to "old age". We are now wiser and understand that the tendency to develop these losses probably runs in families and is aggravated by the noise pollution in our society. In fact, the gene for bringing this hearing loss may be located on the chromosome very near the gene for longevity, thus explaining why older people so often have this type of hearing loss. A preventable cause of such loss is work exposure to loud noises. Certain medications, occasionally required in the treatment of life-threatening infections, have been found to damage the hearing nerve.

The person who has this hearing loss usually doesn't know it. The damage usually occurs gradually and since we usually don't know what is going to be said to us, we can only accept what our ears tell us as the truth. When hearing deteriorates to a moderately severe level we finally become aware what our ears are telling us can’t possibly be correct. People who have normal hearing and who know what they and others are saying know that the person with sensorineural loss has lost hearing before they do.

People with nerve loss have problems communicating with friends and family. Though they hear what is being said, they often hear it incorrectly, and having a conversation becomes very difficult. Often, families give up trying to get through to the person who has a nerve loss. It is a rare friend who continues to try. For the person with nerve hearing loss, a public gathering such as a party or a performance is a disaster. Often the person with a nerve hearing loss begins to avoid going into public without realizing why. The telephone becomes a major source of communication since it is easier to understand on the telephone than face-to-face at a moderate stage of deterioration. This explains why so many of our senior citizens spend so much time on the telephone speaking to people whom they could probably just as easily visit face-to-face.

Through the next few decades, we don't foresee any readily available surgical or medical treatment for most nerve hearing losses. The best ways to improve communications include:

· Controlling the Listening Situation
· Amplification Devices
· Ear Surgeons Watching Ear Implants Ear Implants With Great Interest
For more information regarding these topics consult with your ENT specialist