Effect of Probe-Tip Placement on Impedance Audiometry

Abstract

Introduction: Impedance audiometry measures intactness of middle ear system and acoustic arc. It has become an essential tool in audiological practice, any variability leads to erroneous diagnosis. The most likely error to occur is by different probe-tip placements in the ear canal. The present study was conducted to verify this hypothesis. Subjects, Material and Methods: The study was conducted on twenty normal hearing subjects (40 ears) with age range of 17 to 28 years. It included measurements of compliance, ear canal volume, middle ear pressure and acoustic reflexes. These parameters were studied for two probe-tip positions (i) ≤1mm; and (ii) 2mm inside the ear canal. Results: Significant differences were observed between the two probe-tip positions for ear canal volume. During acoustic reflex for 2000 Hz probe-tone, the change in compliance was significantly affected. Conclusions: The results can be explained by ear canal resonance principles. Thus, the study verifies that the placement of probe-tip affects the measurements of tympanometry and acoustic reflex testing. Aim and Objectives: To study the changes of tympanometric and acoustic reflex test measures with different placements of probe-tip.