Global Health and Hearing Loss
16.10.2017
Hearing loss is a major public health problem, affecting 360 million people worldwide. It is the third most common health problem in the United States (US) – with about 48 million Americans having lost some degree of hearing. It affects quality of life and relationships, and may result in depression, social isolation, unemployment, high blood pressure and increased risk of falls. Major factors that cause and facilitate hearing loss include aging, illness, genetics, medications and noise.
Statistically, humans begin to lose hearing from about 30 to 40 years. Age is the strongest predictor of hearing loss among adults aged 20 and above, with the greatest burden on people aged 60 and above. Age related hearing loss is called Presbycusis, and occurs gradually as individuals become older- one third of people aged 65-74 and about half of people aged 75 and above. This could be as a result of the fact that over the years, the ear’s efficiency to hear gradually wears out due to the following: changes in the structures of the inner ear, changes in blood flow to the ear, impairment in the nerves responsible for hearing, changes in the way that the brain processes speech and sound, damage to the tiny hairs in the ear responsible for transmitting sound to the brain, diabetes, poor circulation, exposure to loud noises, use of certain medications, family history and smoking. There is no cure for age-related hearing loss; however, doctors may recommend the following to improve hearing: hearing aids, assistive devices, such as telephone amplifiers, lessons in sign language or lip reading and cochlear implant. In addition to aging, noise is another factor that wears out hearing especially when it’s loud or constant. Some jobs such as Carpentry and Plumbing increase the risk of hearing loss since workers are exposed to dangerous noise levels daily- 44% of carpenters and 48% of plumbers report some hearing loss .
Based on which part of the auditory system is affected, there are 3 major types of hearing loss and they include sensorineural, conductive and mixed hearing loss. Sensorineural hearing loss occurs when the inner ear (cochlea) or hearing nerve in the brain is damaged. Some possible causes are aging, excessive exposure to loud noise, viral or bacterial infections, medications, ear tumor and other hereditary factors. Conductive hearing loss occurs when there is inefficient conduction of sound through the ear canal, ear drum or middle ear. Possible causes include ear infection, presence of fluid or foreign objects in the middle ear, scarring of the eardrum, build-up of wax, ossicles dislocation, otosclerosis and tumors. Finally, mixed hearing loss results from a combination of sensorineural and conductive hearing loss, affecting both the middle ear and inner ear. Hearing loss can also be classified based on the severity of the problem- four classes exist and they include: Mild hearing loss- where it’s hard to comprehend every word in a noisy background; Moderate hearing loss- where words have to be repeated before they’re comprehended; Severe hearing loss- where it becomes difficult and impossible to follow a conversation without a hearing aid and Profound hearing loss- where it’s impossible to hear people unless they shout.
Symptoms of hearing loss vary broadly depending on the type, cause and severity of the problem. In general, affected people may experience one or more of the following: difficulty understanding conversations, difficulty hearing without repetition, increased difficulty communicating in noisy environments and tinnitus, or ringing sounds in the ears. Hearing loss can be diagnosed by a series of tests such as initial examination using an otoscope, pure tone test, bone conduction test, speech test, tympanometry and audiogram. Given that most cases of hearing loss are untreatable, irreversible and can only be managed, it is best to prevent the problem. Recommended prevention methods include avoiding repetitive exposure to loud sounds and wearing ear protection when exposed to loud sounds.