Hearing loss is very case specific because one person who has hearing loss or impairment may be able to hear certain sounds or be completely deaf.
Impairment entails something is not working as well as it should but there may still be some basic functioning. Hearing loss can go by many terms such as deaf, deafness, or hard of hearing. All could be one and the same situation but as pointed out, each individual is suffering from their own individual illness or situation and may or may not be comparable to any other hearing loss situation.
Although this report focuses on hearing loss as it is associated to military service, it is important to note that in the United States; approximately three of every thousand newborns are born with some type of hearing impairment thus making it one of the more common birth defects in our nation. This entails that there are many public and private organizations and foundations diligently working towards a cure. Until there is a solution however, the problem will continue to affect millions of individuals at birth. but, as we are now well aware, hearing problems can and do develop later in life and terms of service in the armed forces has a high incidence of hearing loss and tinnitus associated to it.
To understand how the ability to hear can be lost, it is important to first understand how hearing works. Although this is a simplified view, it is generally enough to clarify the situation. The human ear consists of three different subdivisions:
the outer ear the middle ear the inner ear
When functioning properly, these three unique parts work together and therefore a person has the ability to hear and process sounds. The visible outer ear or pinna functions as a cone that receives and slightly filters sound waves.
These sound waves travel through the outer ear canal and bounce off of or hit the eardrum in the middle ear. The middle ear's eardrum begins to vibrate and these vibrations move three very small bones within the middle ear. These bones are called the malleus or hammer, the incus or anvil and the stapes or stirrup.
The malleus, incus and stapes function is to help direct the sound waves in a certain direction into the inner ear. The vibrations that were triggered by the sound waves in the middle ear then travel to the cochlea which is filled with liquid and lined with cells that have thousands of tiny hairs on their surface.
The vibrations move the hairs and allow the hairs to change the original sound vibrations into nerve signals which are then forwarded to the brain for interpretation. This process is an extremely well meshed orchestra of events that gives is one's ability to hear.
It is also important to understand the various types of hearing loss and there are relatively few different types of hearing loss:
conductive sensory mixed (conductive and sensory combined) neural
Conductive hearing loss occurs if and when there are associated problems with any part of the outer or middle ear. Individuals with conductive hearing loss find that it is often only a mild hearing loss and it can be more than likely temporary if one receives medical treatment. Sensory hearing loss occurs when the cochlea is not functioning as it should. This type of damage could happen if the hair cells are damaged or destroyed or if the liquid that should be within the cochlea is leaked in some way.
Depending on the type of loss, the range of hearing loss could range anywhere between a person hearing only muffled sounds to not that individual not being able to hear any sounds. Sensory hearing impairments are in most cases permanent and may even affect a person's ability to speak normally and have linked to loss of overall balance.
Neural hearing loss is an internal issue with the connections between the cochlea and the brain and therefore implies that there is some sort of associated nerve damage or maybe even that the path of entry to the brain may be blocked or damaged in some way or manner.
Causes of hearing loss can very: besides birth defects, some specific causes of hearing loss can be attributed to:
middle ear fluid serious infections, such as meningitis head injury listening to very loud music, especially through headphones repeated exposure to loud sounds, such as machinery or explosions
If the inner ear's own antioxidant defenses are overwhelmed injury or even death and permanent loss of the sensory cells of the inner ear occurs. This leads to permanent hearing loss and often also tinnitus, or the sensation of ringing in the ear. The technology licensed by ABG from the Navy boosts the inner ear antioxidant defenses to prevent or treat the damage caused by the toxic ROS. Preventing and treating acute injury to the cochlea or hearing organ in the inner ear may also reduce tinnitus in the acute setting." (PR Newswire, 2003)
In a recent news release meant to raise public awareness regarding several clinical hearing-aid trials which were the first of their kind because they were designed to aid hearing loss victims through mechanical correction in both quiet and noisy situations, another piece of surprising information was released.
The interesting information was not that the hearing aids could probably help millions of Americans deal with sensorineural hearing loss or other forms of nerve-related hearing losses -- the interesting data was how many military veterans were affected by hearing loss. "Department of Veterans Affairs (VA) and the National Institute on Deafness and Other Communication Disorders (NIDCD) conducted this rigorous scientific testing among 360 men and women aged 29-91 years with bilateral sensorineural hearing loss. About 70% were military veterans, and about half never used a hearing aid." (Beasley, 2004)
The United States military is currently investigating the situation. "A congressionally mandated study by the Institute of Medicine will assess noise-induced hearing loss and tinnitus associated with military service from World War II to the present, the effects of noise on hearing, and the availability of audiometric testing data for active duty personnel." (IOM Board: Medical Follow-Up Agency, 2004)
The armed forces have implemented an expert committee tasked with discovering the magnitude of the hearing loss problem as well as being charged with providing viable recommendations and solutions for the Department of Veterans Affairs. In the face of such pressures, safety and health experts are paying more attention to metrics in general, and hearing conservation is no exception. The military can no longer overlook the affects of noise-induced hearing loss and tinnitus associated with service in the Armed Forces.
The committee will attempt to review the plethora of staff-generated data about compliance and existing regulations for audiometric testing throughout the services during various periods of time since World War II. There should be a great deal of information for the committee to review and assess on hearing loss and that should lead to long overdue suggestions to help identify the many military sources that create damaging toxic noise during active duty.
The committee has the objective of identifying what the actual levels of noise exposure is needed to cause hearing loss or tinnitus as well as determining if those levels of noise exposure can somehow be delayed or mitigated. "Staff of the Medical Follow-up Agency will identify populations of veterans from each of the armed services (Army, Navy, Air Force, Marine Corps, and Coast Guard) and from each of the time periods from World War II to the present. The service medical records of a sample of these individuals will be obtained and reviewed for records of audiometric surveillance (including reference and termination audiograms)." (IOM Board: Medical Follow-Up Agency, 2004)
From that information, the committee can supposedly make the necessary suggestions of viable alternatives and solutions for the obvious risk factors associated to noise-induced hearing loss and thereby establish and implement new criteria for hearing conservation measures adequate for protecting service members in the same light as the Occupational Safety and Health Administration would do in the civilian business environment.
To demonstrate how crucial this committee's findings could be, during a recent congressional inquiry one returning veteran from Iraq pointed out the historical support soldiers and reservists suffering with hearing loss received by both the active military and the Veterans Administration. "My MEB process spanned over a nine-month period. On my physical exam my complaints of depression, tremors, vertigo, severe headaches, ringing in my ears, numbness to both arms and hearing loss were blatantly ignored and, in my opinion, purposefully, left off the Medical Evaluation Board Findings (DA 3947) which has prolonged my MEB process, which prolongs the time that I can seek competent medical and psychiatric care from the civilian world, and be close to my caring family My depression had become so severe I went to sick call and was told to return the next day."…