Hearing loss typically produces a reduction in the perception and comprehension of sound, particularly under challenging listening conditions. In some cases, hearing loss is so mild that the patient doesn't notice the problem until it is discovered on a hearing test. When hearing loss is more severe, sounds may seem distorted and conversations may become muffled or hard to understand, particularly when in a social setting with background conversation or in rooms with echoes. The patient may fail to answer doorbells or telephones and they may constantly ask friends and relatives to speak louder or to repeat words. Newborns with severe hearing loss do not startle at loud sounds. If left unattended, children with hearing problems experience difficulties in language development. Sometimes, if hearing problems are not diagnosed at an earlier age, the first symptom of hearing loss in a school-age child may be academic troubles, not because of a learning disability, but because the child simply can't hear what is being taught and may be showing some signs of language deprivation.

Hearing loss may be associated with different types of health problems, but the end effect is one of two basic types of hearing loss; Sensorineural and Conductive.

Sensorineural hearing loss is an interference in the transmission of sound impulses from the inner ear to the brain. It is most often not reversible, but can be most can helped with amplification. Some of the important causes of sensorineural hearing loss include:

	Aging - A decrease in hearing is common with age. This condition is called presbycusis. Age-related hearing loss is generally thought to be a decline in the nerve function of the ear as a person ages. The main area of injury in age-related hearing loss is in the cochlea, a snail-shell-shaped structure that generates the first electrical impulse for hearing. There is usually a loss of cells that pick up the tones, particularly in the high-frequency portion of the cochlea. As these cells are damaged, the cells lose their ability to transmit sound in the form of pitches. The degeneration may progress to involve the nerve fibers that connect the ear and brain. The loss is so gradual that a person may not know that it has happened. Most people over the age of 65 have some hearing loss and by age 80, almost everyone does.
	Noise-induced hearing loss - Intense sounds of greater than 75 decibels cause damage to the inner ear. Damage may occur because of a single exposure or from many exposures over months or years. Typically, noise produced by machines or weapons is the most damaging. Some examples of noises that can cause noise-induced hearing loss include: motorcycles, lawnmowers, wood working tools, loud rock music, firecrackers, and gun fire. Viral and bacterial infections - Common childhood diseases, such as mumps, measles, scarlet fever, whooping cough, meningitis, and extended high fevers can cause hearing loss. Having these diseases does not guarantee hearing loss, but these should be followed up with a hearing test.
	Medications - Some medications may reduce hearing sensitivity by damaging hair cell receptors within the inner ear. These include: aminoglycoside antibiotics such as gentamicin, tobramycin, amikacin, and streptomycin; erythromycin (when given intravenously); and vancomycin (when given to patients with poor kidney function).
	Meniere's disease - Meniere's disease is thought to be due to a change in the volume of fluid inside the inner ear. The hallmark of Meniere's disease is fluctuant hearing, spells of dizziness and a sense of fullness in the affected ear. Although the reason for this change is unknown, scientists suspect that it may be linked to prior viral infections of the ear, or to biological factors inside the ear itself. Currently three to five million Americans suffer from Meniere's disease, with about 100,000 new cases diagnosed each year.
	Acoustic neuroma - (also called "vestibular schwannoma") - An acoustic neuroma is a tumor which is located between the ear and the brain, and which usually affects balance as well as hearing. Acoustic neuromas affect 2,000 to 3,000 Americans each year, or about one in every 100,000 Americans. In 95 percent of cases the tumor affects only one ear, and in 5 percent of cases the problem is linked to an inherited syndrome called neurofibromatosis type 2. The possibility of an acoustic neuroma should be considered when there is a hearing loss in one ear only.

Conductive hearing loss is a blockage in the transmission of sounds from the ear drum to the inner ear. It is sometimes reversible with medical attention. Some of the most common causes of conductive hearing loss include:

	Obstruction of the ear canal by ear wax or a foreign object - Sometimes the ear canal can become occluded with wax or some other object and sound cannot travel down the ear canal the way it should. If this is the case, the wax or object can be removed by a professional and hearing may improve. Simple irrigation systems can be purchased at a pharmacy and used to remove wax at home, but cotton swabs, hair pins and other objects should never be placed in the ear to remove wax. The wax is likely to be pushed down further into the ear canal and then become more difficult to remove. In addition, permanent damage can result from placing any of these objects in the ear canal. The safest solution is to have a medical professional such as a physician nurse or audiologist examine the ear and remove any obstructive wax or object.
	Perforation or other damage to the ear drum - Perforations of the ear drum can be caused by various conditions such as head trauma and ear infections. When the ear drum has a hole in it, it is not able to vibrate as efficiently and pass the sound to the nerve.
	Otitis Media - Inflammation of the ear (sterile otitis or serous otitis) may occur when there is a collection of sterile fluid in the ear. This may be caused by overproduction of fluid by the structures in the middle ear. It may also be caused by blockage of the Eustachian tube, which connects the middle ear and the back of the nose/upper throat. The presence of excess fluid causes the ear to become irritated and inflamed. Acute otitis media (acute ear infection) occurs when bacterial or viral infection develops in the fluid of the middle ear. This condition can produce hearing loss because sound cannot travel through a fluid filled space as efficiently as it can an air filled space.
	Otosclerosis - Otosclerosis is an inherited disorder involving the growth of abnormal spongy bone in the middle ear. This growth prevents the stapes (stirrup bone) from vibrating in response to sound waves, thus leading to progressive conductive hearing loss. Otosclerosis is the most frequent cause of middle ear hearing loss in young adults, affecting about 10% of the population of the U.S. Otosclerosis usually affects both ears, and is most commonly seen in women, 15 to 30 years old. The disorder can be addressed with a hearing aid or corrective surgery.

When hearing loss is present it is very important to know what kind it is. An audiologist at Midland Hearing Associates can help determine the cause of your hearing loss and make recommendations as to the best way to treat it. When medical intervention is necessary, the audiologist can provide referrals to several qualified physicians specifically trained to treat your specific problem.