Deafness - a hearing loss is when a man can not hear at all, or the degree of hearing loss is so strong that the perception of speech sounds becomes impossible.
Physiology of Hearing
The organ of hearing consists of a sound-conducting and sound-pieces. Each constituent part of the process of evolution adapted to best perform its tasks. For example, the shape of the human ear to better pick up sounds and auditory canal improves the quality of the sound.
The structure of the acoustic analyzer can be identified:
- The outer ear (pinna, external auditory meatus);
- Middle ear (tympanic membrane, auditory ossicles, tympanic cavity);
- The inner ear (the cochlea, the semicircular canals, the organ of Corti)
- The conductive path;
- Cortical areas in the brain.
The sounds that we hear are the mechanical vibrations of the air space. These fluctuations cause the eardrum to the inner ear, which resonates with their own frequency. Further transfer of vibrations by means of the auditory ossicles (hammer, anvil and stirrup) and liquid (endolymph) in the labyrinth of the inner ear. Located in the liquid hair organ of Corti (in fact, they are sensitive cells) was converted mechanical vibration wave in the auditory nerve impulses that are then transmitted along the nerve fibers to the brain.
Now it is known that the causes of deafness can be set.
Hearing loss may occur from the constant noise at work (so-called noise trauma), after suffering otitis media (ear infection), meningitis (inflammation of the meninges), or toxic effects on the auditory nerve of the aminoglycoside antibiotics. The cause of deafness can be a scarlet fever, respiratory virus and certain other communicable diseases. The trauma of the temporal bone may result in a violation of the structure of the organ of hearing, or the integrity of the auditory nerve and, as a consequence - deafness.
Types of deafness
Completely missing the hearing rarely. More often there are situations where continued residual audibility, and the person is able to distinguish between very loud speech or some of its frequency. These states are called deafness. A clear distinction between the definition of hearing loss and deafness is difficult and depends on the method of investigation.
If a person has lost his hearing before learned to speak, he can remain deaf.
On the origin of the following types of deafness:
- Hereditary (passed down from generation to generation, is associated with chromosomal abnormalities);
- Congenital (appeared in the adverse effects on the fetus during its intrauterine development or at the time of delivery);
- Acquired (as a result of age-related hearing organ, disease, injury, toxic effect of some medicines, etc..).
In the place of the damage of the auditory analyzer is isolated conductive and sensorineural deafness. Sensorineural hearing loss occurs when the hearing impaired the formation of pulses, their conduct or the perception in the brain. The cause of deafness conductive type are abnormalities in the conducting apparatus of the auditory analyzer (trauma of the ear, otosclerosis, and others.).
Deafness is also classified according to the degree of hearing loss.
The development of the organ of hearing in the embryo begins with 5 weeks of intrauterine life. At 20 weeks' gestation, the unborn child already has the inner ear, the degree of maturity comparable to adults. Since that time the baby is in the womb begins to distinguish sounds of different intensity and frequency.
Congenital deafness occurs due to pathological influence of some factors on the fetus and damage components of the auditory analyzer. The degree of hearing loss as a result can vary widely - from total deafness (meets at 0, 25% of newborns) to its slight decline.
Among the causes of congenital deafness often note infections (mostly viral, such as measles, rubella, influenza), the toxic effect of medicines taken by the mother during pregnancy (sulfonamides, aminoglycoside antibiotics and others). In the occurrence of a number of cases of congenital deafness scientifically proven toxic effects of alcohol.
Identification of deafness
The problems involved in hearing loss doctor audiologist, although initially the patients most likely to seek help from the otolaryngologist.
Deafness can occur suddenly or gradually, quite imperceptible to humans. Complaints about deafness require additional tests. Modern techniques and accurate instruments allow to objectively evaluate the degree of deafness and hearing remnants.
Hearing loss should be identified as early as possible after birth, because it depends on the child's level of development and the degree of adaptation and the possibility of restoring hearing aid.
Already in the neonatal period, in many hospitals conducted a screening study special audiometry auditory function of all children. Audioskrining holds prior to discharge from the hospital by trained staff. This is a quick, painless and completely safe method of detection of congenital deafness. Adults may conduct speech audiometry.
Treatment of deafness
Hearing heavily affect the quality of human life, so when incomplete deafness correction is possible with the use of his hearing aids amplify sounds. This so-called electro-acoustic correction.
Pharmacological treatment of deafness are ineffective, often requires plastic or arthroplasty.
Recently used in the treatment of deafness hearing aids with special electrodes implanted into the inner ear (cochlear implants). Intensively developing at the microscopic level of the inner ear surgery (tympanoplasty, stapedoplasty etc..).
Corrections amenable to most types of conductive deafness.