AmpliVox Otowave 302+, Инструкция по эксплуатации

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PRINCIPLES OF OPERATION
20 OTOWAVE 302+ INSTRUCTION FOR USE
3.4. ACOUSTIC REFLEX MEASUREMENT
Using the same principle as in tympanometry measures, it is also possible to establish whether an acoustical reflex is
present. The acoustic reflex is caused by the contraction of the stapedial muscle as a response to high-intensity
stimulation of the ear. The acoustic reflex is also a natural protection of the inner ear from too high sound pressure
levels and thereby damage of the hearing organ.
In acoustic reflex testing, the 226Hz tone is used to measure the admittance of the ear, while a short tone at a different
frequency is presented (the reflex stimulus). The level of this stimulus is increased in steps until the stapedial muscles
respond causing the tympanic membrane to become stiffer, or a preset maximum level is reached. When the change in
admittance exceeds a predetermined threshold, this constitutes a reflex and the change in admittance at that level
when the stimulus is applied is displayed as a plot against time.
The stapedial reflex is measured at the static ear canal pressure that produces the maximum membrane admittance, so
reflex measurements are taken after the tympanogram is measured when the peak admittance pressure has been
established.
The reflex stimulus may be produced in the ear being measured (ipsilateral mode), the opposite ear (contralateral mode)
or in both ears (ipsilateral mode followed by contralateral mode). For contralateral stimulation the reflex tone is
produced in a separate transducer supplied with the instrument.