Acoustic impedancemetry - a complex diagnostic procedures that are carried out to assess the state of the middle ear, is responsible for the transmission of sound vibrations of air.
Anatomy of the ear is designed so that existing auditory reflex acts as a protective mechanism: under the influence of strong sound vibrations tense muscles of the tympanum, deformed chain of auditory ossicles and tympanic membrane and there is resistance to vibrations of sound, protects the sensitive hair cells. Impedance makes it possible to verify the extent of this resistance. Based on the acoustic stimulation of the middle ear impedancemetry enables objective evaluation of the eardrum, the auditory ossicles and the pipe, the pressure in the middle ear, to find out if in the middle ear fluid or scarring.
In addition, impedancemetry ear enables secure reduction of muscle and evaluate hearing threshold of the acoustic reflex, including threshold of discomfort to differentiate the diseases of middle and inner ear: otitis, tubo-otitis, otosclerosis, a disease to confirm or deny the auditory nerve.
Ear impedance includes tympanometry and research of the auditory reflex.
Under the method of impedance - tympanometry meant checking the mobility of the tympanic membrane under the pressure of the air in the external auditory canal. Assign tympanometry in diseases adenoids, pathologies of the eardrum and the eustachian tubes, middle ear disease, hearing loss, after suffering otitis.
Conducts tympanometry audiologist doctor after examining the ears, removing sulfur masses (if necessary) and clarify the essence of the test to the patient. This procedure takes impedance as follows: the doctor inserts into the ear canal and a small rubber tube comprises device - impedance, which is using a special pump changes the pressure in your ear and makes the eardrum move. The pressure in the ear canal is measured using a small microphone connected to a probe inserted into the ear. The procedure is painless, the patient feels the same pressure in the ear, like when climbing in the mountains or during the flight, and hears a squeak. During acoustic testing can not chew, move and talk. Tympanometry lasts 5-10 minutes, results audiologist doctor to analyze the patient's condition gets instantly.
The second method of impedance - the study of the auditory reflex, based on the pitch in the ear to loud sound stimulus. The sound is fed directly into the ear canal, through headphones, earpiece, or tube. Stimulus passes through the middle ear reaches the cochlea. From the information about the intensity and frequency of the sound is transmitted to the brain stem through the eighth nerve, which is determined by a sufficiently intense sound stimulus for the reflex response. With sufficient intensity occurs sided reflex response: impulse passes through the seventh nerve on both sides of the stirrup to the muscles and causing their decline. Sound incentives for research reflex is 85 dB in one ear.
If the reflex response is not present, the volume level increases gradually, dB and 10, until a reflex response - reduced muscle stapes to 0, 05sm.
Acoustic impedance is used not only to diagnose diseases of the ears and hearing pathologies, but also for the selection of the hearing aid, cochlear implantation of. In these cases, inspection of the state of the middle ear combined with tone audiometry. Use ear impedance and control examination in the treatment of myasthenia gravis and facial paralysis.