Deafness is the total absence of hearing or this degree of reducing it, in which the perception of speech is impossible.
Absolute deafness is rare. Usually there are remnants of hearing, allowing to perceive very loud sounds, including some speech sounds, spoken in a loud voice about the ear. Discerning of speech perception at deafness is not achieved; this deafness is different from hearing lossin which sufficient sound provides the possibility of voice communication.
Deafness may be congenital or acquired. Congenital deafness occurs as a result of incorrect prenatal development of the hearing body, which may be due to the influence of hereditary factor and its impact on the fruit of infection or intoxication. Practical importance in the occurrence of congenital deafness are viral infections (measles, influenza), the alcohol consumed by the mother during pregnancy, some of medicinal substance (streptomycin, kanamycin, monomitsin, quinine and other), injury to the foetus. A particularly harmful impact of all these factors in the first months of pregnancy, when the rudiment of the organ of hearing especially vulnerable. The cause of acquired deafness most often inflammatory processes in the inner ear and the auditory nerve, developing or as a complication of acute and chronic middle ear infections (see), or as a result of some infectious diseases, epidemic cerebrospinal meningitis, measles, scarlet fever, mumps, influenza. In pre-revolutionary Russia was often observed occupational deafness among the boilers and weavers that occurred in the result of prolonged exposure to the organ of hearing a lot of noise and vibrations. Already in the first years after the October revolution were conducted extensive protection measures working noisy production (reduction of noise and vibrations, the use of special of protivosokove, replacement of some particularly noisy processes less noisy, such as hand-riveted by electric welding).
The diagnosis. Modern methods of research of hearing (see Audiometry) allow with a high degree of accuracy to determine the absence or presence of residual hearing. Significant differences occur recognition of deafness in young children. The conventional methods of research of hearing (speech, tuning forks, audiometer) does not reach the goal, as these children do not understand the tasks set before them. In these cases it is more appropriate use of sounding toys. The presence or the absence of reaction to published toys tones help to determine if the child has a hearing.
In those rare cases, when analyzed reason hides the true state of the hearing and pretends to be deaf, apply special methods for detection of hearing. One of the most simple is the way of the Pawnshop. Investigated offer to read out loud or to conduct an oral account and at this time muffle his ears with noisemakers or headphones through which is passed to the loud music. When this deafness voice studied not changed. When the imaginary deafness investigated seeking to block his voice noise of soglasites owing to what the volume is read or account is noticeable. The presence of hearing loss can sometimes be identified by reflexes Bekhterev and Shurygin: with a sudden switch on sound closed eyelids blink, or Auro-palpebralis, reflex Bekhterev) and a narrowing of a pupil (pupillary, or Auro-pupillary, reflex Shurygin).
Treatment. Pathological processes in the nervous elements of the organ of hearing usually lead to a stable and irreversible changes. Therefore, the treatment of deafness is in most cases ineffective. In the case of partial deafness some improvement hearing can sometimes be achieved by the use of drugs of strychnine, nicotinic acid, vitamin B1, extract of aloe and other stimulants. In cases where deafness is caused by the defeat of the conductive system, for example when otosclerosis, improved hearing is achieved by developed recently suholuch operations (stapedectomy, fenestration of the maze). In the speech communication with other great help deaf provides mastering the skill of visual perception of speech (read lips). With significant balances of hearing the famous favor can bring sound amplifying devices (see Hearing AIDS), as well as auditory exercises (reeducate hearing).
Prevention. In the prevention of congenital deafness focus is prevention of viral infections, the prohibition of taking some drugs, alcohol, etc. are Not recommended marriages between innate and deaf. Prevention of acquired deafness is the prevention and timely treatment of the disease, leading to permanent hearing impairment, and also in eliminating harmful factors at work and in everyday life (noise, vibration, intoxication). You should not absolutely necessary to use large doses of antibiotics such as streptomycin, kanamycin, monomitsin. A special caution in the use of these funds is required in the presence of pathological processes in the hearing organ.
Congenital or acquired during early childhood deafness deprives the child of the possibility to acquire speech and requires special methods of training (see Deafness).