1987 Volume 30 Issue 6 Pages 753-758
Effect of attic obstruction on the middle ear sound transmission was measured simultaneously by two different methods in four fresh human cadaver temporal bones. In the visual method, the displacement of the manubrium tip of the malleus (umbo) to a constant sound pressure of 124dB SPL at the TM was measured before and after attic obstruction under microscope with stroboscope illumination combined with a video measuring system. In the acoustical method, the effective sound pressure (SP) which was transformed into the energy of vibration of the TM, was measured before and after obstruction of the attic. The effective SP was obtained from three parameters; the SPs in front and behind the TM, and the phase difference between them. The results by two methods were in good accordance and showed that the attic obstruction improved middle ear sound transmission by 7±2dB at 2.4-3kHz and worsened it by 6±2dB at 0.6-0.8kHz.
