The sense of hearing is a special sense by which we perceive sounds and interpret their meaning. The auditory system consists of the ear, the auditory nerve, and parts of the central nervous system that are involved in the sense of hearing. Sounds waves vibrate, and our ear collects those vibrations and converts them into nerves impulses, which are often sent to certain parts of the brain and interpreted that way.
The ear consists of three parts
Outer ear - consists of the earlobe and ear canal. The ear shell captures and collects sound waves from the environment and directs them to the ear canal, which conducts them to the next part of the ear - the middle ear, which consists of the eardrum, three small bones (hammer, anvil, stirrup) and Eustachian tube.
Its function is to transmit sound signals to the third part of the ear - the inner ear - which consists of a snail and semicircular canals. The role of this part of the ear is to convert sound waves into nerve impulses that are further transmitted through auditory nerve to certain parts of the brain where they are deciphered and as final result gives us a sense of hearing.
A healthy human ear hears external sounds in the frequency range from 16 to 20,000 Hz. Frequencies below 16 Hz (infrasound) are felt as vibrations, and frequencies above 20,000 Hz represent ultrasonic frequencies.
What can be hearing impairment?
Hearing impairment can be divided according to the time of occurrence and according to the place or location of the impairment.
According to the time of their occurrence, we divide them into congenital and acquired hearing impairment. Congenital hearing loss occurs in one to three per 1,000 live births. It is of the sensorineural type, which means damage at the level of the inner ear and the auditory nerve. Congenital hearing impairment adversely affects the child's speech and language development. That is why children's audiology is extremely important in the early recognition of mild deafness and total deafness. This is especially important because of the early rehabilitation of hearing and because of the later speech and language development of the child. That is why screening measurement of hearing for babies in maternity hospitals has been introduced in our country (Serbia). Acquired hearing impairment is of various etiologies. It can be a consequence of a prenatal viral infection (rubella, cytomegalovirus, herpes simplex virus). Premature babies are especially at risk for hearing loss. Low birth weight, hyperbilirubinemia, difficulty breathing at birth, hypoxia - all these are risk factors that require monitoring of the child's hearing during the first years of life.
Hearing loss can be caused by ototoxic drugs, such as gentamicin, neomycin, streptomycin.
Acquired hearing loss can be can be result of bacterial meningitis or encephalitis , trauma or a sudden strong sound stimulus.
Finally, acquired hearing impairment can also be of idiopathic nature, when the exact cause of sudden hearing loss isn't known.
Early deafness or presbycusis is a type of acquired progressive hearing impairment. It is manifested by a decrease or loss of auditory sensitivity (sensorineural hearing loss) that occurs as a result of a combination of hearing cell degradation at different levels of the auditory system and chronic exposure to noise. Damage can occur gradually or suddenly, in one or both ears, equally of differently in one or the other ear. Sensory loss affects every third person over the age of 65 or every second person over the age of 75.
Hearing impairment according to the place of origin
According to the place of origin, hearing impairments are divided into conductive and perceptual hearing impairments. Conductive hearing loss or conduction damage causes limited sound transmission through the outer and middle ear. It is usually caused by inflammation of the middle and outer ear, ear injuries or accumulation of ear fat in the ear canal (cerumen). Perceptual hearing impairment occurs as a consequence of damage to the structures of the inner ear that allows the conversion of sound waves into nerve impulses or damage to the auditory nerve that transmits these impulses to the brain.
What is mild deafness and higher deafness from that?
Mild deafness and higher deafness from it are two special pathological conditions that affect your sense of hearing and differ according to the size of the hearing impairment.
Mild deafness is a hearing impairment of 25 to 80 db, and according to the degree of hearing impairment, hearing loss is divided into:
Mild - hearing impairment from 25-35 db;
Moderate - hearing impairment from 36-60 db;
Severe - hearing impairment from 61-80db.
Deafness is considered to be hearing loss at speech frequencies greater than 81 db. Speech frequencies are frequencies between 500 and 4000 Hz.
Deafness can be:
- Total or clinical, when the person has no feelings or hearing;
- Practical, when there are individual remnants of hearing, most often in frequencies lower than 500 Hz.
Diagnosis of hearing impairment
A patient who has a feeling of hearing loss should be immediately referred to an otorhinolaryngologist, who will with otoscope examine the ear and audiological treat the patient.
This method objectively assesses whether there is hearing loss. If there is, it is estimated what that loss is. Basic audiological processing includes audiometry performed using an audiometer apparatus. During this examination, the patient wears earphones through which different tones are played first to one ear and then to the other. The patient is asked to answer when he hears the first highest tone. The method is simple and the examination doesn't take long. Another audiological method is tympanometry, which assesses the ability of the eardrum to receive sounds.
Depending on the findings of these tests, further necessary diagnostics, therapy and treatment of the patient are planned.
Treatment of impaired hearing
If it is an eat fat that blocks the ear canal, rinsing the ear with enough water that solves the problem. Ear infections with hearing loss, caused by a stuffy nose or tonsillitis, are common in children. In such cases, antibiotic therapy is included along with nasal cleansing and decongestive nasal drops. In some cases, when the contents of the middle ear are determined by tympanometry's examination, due to which the patient is less able to hear, a surgical procedure is suggested in which ventilation tubes are placed the eardrum. The tubes stay in the ear for about six months, after which they are removed or fall out on their own. After that, the hearing returns to normal and there no consequences on the eardrum and middle ear. This procedure is more common in children.
If ossification of the middle ear (otosclerosis) is diagnosed, by removing the diseased bone and replacing it with a prosthesis, hearing improves. If hearing cells are found to be damaged at the level or the inner ear, it is recommended to wear a hearing aid. If severe hearing disease is diagnosed at the level of the middle or inner ear, where the remnants of hearing are minimal or can't be registered, and are measured practically with deafness, it is suggested to install an artificial ear - cochlear implant which returns hearing to the patient , with later rehabilitation.
Prevention of hearing loss
Hearing loss often causes depression, anxiety and feelings of rejection in society. Therefore, such patient should be taken seriously and treated carefully.
In order to combat hearing loss due to external factors - noise, especially in younger people, it is necessary to inform young people about the harmful effects of noise and loud music on the state of hearing. Simple preventative measures, such as lowering loud music and using hearing aids in a noisy environment, can reduce the side effects of noise. Older people who have been diagnosed with hearing impairment should be informed about the benefits of using hearing aids and remove the fears and prejudices that always exist about their use.
Hearing loss is a common problem that occurs at all ages and is an important social and medical problem. Modern medical methods of diagnosis and treatment of hearing impairment can significantly help patients with such a problem, and enable them to be reintegrated into everyday life activities.
Literature and images: Lily magazine, number 43, winter 2020/21.
