The functioning of the ear is very complex. It is the organ that helps us hear sounds. Apart from that, ears are responsible for ensuring the body's balance irrespective of its position. While the outer, middle, and inner ear are responsible for the function of hearing; only the inner ear is involved in maintaining the postural equilibrium of the body. Total or partial inability to hear is termed deafness, which is also called hearing loss. It has been suggested that the term deafness indicates total inability to hear, and partial inability is called hearing loss. However, both the terms are often used interchangeably.
Deafness is a medical condition that can be congenital or acquired. If the condition is present during birth, it is called congenital deafness. If a person develops deafness later in life, it is acquired deafness. Both types can be caused by genetic factors.
Types of Deafness
The three types of deafness are conductive, sensorineural, and mixed. In conductive deafness, an impairment of the outer or middle ear prevents the sound from reaching the inner ear, thereby causing deafness. The impairment can be in the form of mild obstructions like excess earwax or ear infection. It can also be due to severe conditions like otosclerosis, where the abnormal growth of the middle ear bone blocks the passage of sound. However, most cases of conductive hearing loss can be cured with medication or surgery.
Sensorineural hearing loss is almost permanent in nature, and is the result of a disorder of the inner ear or auditory nerve. Causes for this type of deafness include heredity, diseases or disorders, exposure to excess noise or some chemicals, head trauma, certain medication, and old age. The third type of deafness is a combination of the other two types.
What Causes Deafness?
Genetic Defects: Deafness is one of the common birth defects. Inherited genetic defects comprise the main cause for congenital deafness. In some people, such genetic defects may cause deafness at a later stage in life. Deafness caused by genetic defects can be conductive, sensorineural, or mixed. It can be syndromic (if associated with visible malformations in the ear or medical problems in other organs. The condition is nonsyndromic, if there are no such abnormalities.
Continuous Exposure to Loud Noise: This is one of the common causes of sensorineural deafness in humans. Such deafness is usually observed in people working at construction sites, airports, and nightclubs. Those working with firearms and heavy equipment are also prone to this condition. Regular and frequent use of music headphones is another reason for such deafness. The longer the exposure, the greater the chance of getting affected with this condition. Sometimes, a single loud explosion is enough to cause deafness in humans.
Diseases and Disorders: Some diseases and disorders are considered as contributory factors for deafness. They include measles, meningitis, certain autoimmune diseases like Wegener's granulomatosis, mumps, presbycusis, AIDS, and chlamydia. Fetal alcoholic syndrome (seen in babies born to alcoholic mothers), is a cause of hearing loss in infants. Growing adenoids can also cause hearing loss, as they can obstruct the Eustachian tubes. Otosclerosis, which is a disorder of the middle ear bone, is another cause of deafness. Head injury may also cause deafness in humans. Diabetes and disorders of the brain and nerves are often linked to sensorineural deafness.
Certain Medication: Some medication may cause permanent hearing loss in humans, while others may lead to deafness which can be reversed. The user may develop vertigo and tinnitus during the initial days of treatment with such medicines. These symptoms may disappear once he stops taking the medicine. However, some medicines cause permanent damage to the inner ear, resulting in deafness. Antibiotics like aminoglycosides are among the commonly used ototoxic medicines. They include gentamicin, streptomycin, neomycin, etc. Others are NSAIDs (like ibuprofen), diuretics, aspirin, and some medicines used for treating cancer. Narcotic pain killer addiction and heavy hydrocodone abuse are often linked to deafness.
Exposure to Industrial Chemicals: Ototoxic chemicals damage the cochlea and some parts of the auditory system, thereby causing permanent hearing loss. Exposure to such chemicals, along with continuous exposure to loud noise can be a dangerous combination that can cause deafness within a short period. Solvents (like styrene, toluene and ethyl benzene), asphyxiants like carbon monoxide, metals like lead and mercury, and pesticides like paraquat, may cause deafness.
Mentioned above are some of the common causes of deafness in humans. It is always advisable to protect the ears from trauma and other injuries. Make sure to wear protective gear in workplaces, where you are regularly exposed to heavy noises. Consult your health care provider as soon as you develop hearing problems.
Disclaimer: This article is for informational purposes only and should not be used as a replacement for expert medical advice. Visiting your physician is the safest way to diagnose and treat any health condition.