Introduction: Laser Doppler vibrometry can potentially be applied in the measurement of the acoustic conductivity of the middle ear during tympanoplasty. Its usefulness in estimating the accuracy of ossiculoplasty requires experimentally verified.
Aim: The article presents the test procedure developed at the Department of Otolaryngology, Medical University of Warsaw for the displacement measurement of the conductive elements of the middle ear.
Materials and method: In the study were used 14 fresh-frozen temporal bones. In the initial stage was performed antrotomy with posterior tympanotomy. During the measurements, ER-2 speakers generated a signal with a frequency of 1000 Hz, 2000 Hz, 4000 Hz, 8000 Hz. Acoustic conductivity of the middle ear was measured on the back branch of the stapes, round window. Laser Doppler Vibrometer was used to measure velocity of each selected elements of the ear. In four experiments were assessed the intraoperative availability of measurement points, the impact of laser beam angle changes and the presence of reflective tape on the amplitude of vibration measured point, intra- and interindividual variability of the method.
Results: For all measured frequencies intra-individual differences were no statistically significant. There were observed large differences between the velocity values in various temporal bones. Changing the angle of the laser beam does not significantly affect the results. Mucosal surface of the tympanic cavity does not reflect the laser beam.
Conclusion: Laser Doppler vibrometry can be used to measure motion of the middle ear sound conductivity with very good repeatability of measurements. Changing the angle of the laser beam should not vary amplitude of measurement during surgery. To maintain the sensitivity of response, it is necessary to use part of reflective tape.