Question
Identify the instrument shown in the picture below ?
A. Impedence audiometer.
B. Galvanic audiometry.
C. Caloric audiometry.
D. None of the above.
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Correct Answer » A Explanation |
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Ans : A. Impedence audiometer.
IMPEDANCE AUDIOMETRY
- Objective test
The following tests are included in the category Impedance Audiometry tests:
- Tympanometry (most commonly used)
- To determine the status of the tympanic membrane and middle ear
- Eustachian Tube Function
- Acoustic reflex thresholds
- To evaluate acoustic reflex pathways, which include cranial nerves (CN) VII and VIII and the auditory brainstem.
- Acoustic reflex decay
TYMPANOMETRY
- Tympanogram is the graphic representation of compliance and impendance of tympanic ossicular system with air pressure changes.
- Tone is delivered at 220 Hz
- By charting the compliance of tympano-ossicular system against various pressure changes, different tympanograms are obtained
TYPES OF TYMPANOGRAM
- Type A – normal middle ear function.
- Type As – (Low compliance) otosclerosis, malleus fixation
- Type Ad (High compliance) ossicular discontinuity or thin and lax tympanic membrane
- Type B – (No change in compliance with pressure changes) middle ear fluid as in Secretory Otits Media, thick tympanic membrane
- Most common cause of Type B tympanogram in an old aged patient with neck nodes is Nasopharyngeal Carcinoma.
- Type C – (Maximum compliance occurs with negative pressure in excess of 100 mm of H20) retracted tympanic membrane.indicates a malfunctioning eustachian tube