Automatic Tympanometry in Clinical Practice

Abstract

The probe tone of an impedance bridge has a direct effect on the results of tympanometry. The frequency of the probe tone should be close to the resonant frequency of the middle ear. Of three electro-acoustic bridges using three different probe tones, i.e. 800, 625 and 220 Hz, the one using 800 Hz provided the most indentifiable tympanographic pattern incases with ossicular discontinuity. Five different types of tympanograms could be indentified when an 800 Hz tone is used

The stapedius reflex thresholds, on the other hand, show only minor differences with different probe tone frequencies

Important clinical information can be obtained by combining the type of tympanogram with the results of stapedius reflex measurements

Key Words:

• Relative impendance of the ear
• Selection of the probe-tone frequency
• Type of tympanograms
• Acoustic reflex threshold
• Conductive hearing loss
• Otosclerosis
• Disruption of the ossicular chain