Maico MI 34 Operating Instructions Manual

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Maico MI 34 Operating Instructions Manual Manual pdf 18 page image

Operating Instructions MI 34 / MI 34 HGEBAmi34e.11a.docx 17 850 232/14 08/11Figure 10The middle earhearingnerveear canalmiddleearbonesear drummiddle eareustachian tubecochleamusculusstapediusFigure 11 – Principle of impedance measurement4 How to create a TympanogramIn the following paragraph we will deal shortly with the principle and thebackground of the impedance measurement to create a betterunderstanding. If you want to begin the measurements immediately justskip this paragraph and continue reading with 4.3 Preparing themeasurements.4.1 The basics of the impedance measurementThe impedance measurementserves the diagnosis of thecondition of the middle ear andcan therefore not be compareddirectly with other audiometricaltests such as sound or speechaudiometry which serve themeasurement of the hearing.Furthermore the impedancemeasurement is an objectivemeasuring method which doesnot depend on the cooperationof the test person and cantherefore not be falsified by him.The two most important impedance measuring methods possible with yourMI 34 are Tympanometry and the measurement of the Stapedius reflexwhich is treated in chapter 5. “How to measure the stapedius reflex”.The impedance measurementexamines the acoustic resistance of themiddle ear. If the eardrum is hit by asound a part is absorbed and sent viathe middle ear to the inner ear whilethe other part is reflected. The stifferthe eardrum is the more sound isreflected and the less sound reachesthe inner ear. In the probe of theimpedance measuring instrument asmall loudspeaker is installed whichemits a sound of low frequency via atube A (see Figure 11) into the