[Laser Doppler vibrometry of the tympanic membrane. Possibilities for objective middle ear diagnosis].

In the diagnosis of hearing disorders, the laser velocimeter can be used to advantage. In contrast to previously published studies on measurements at exposed middle and inner ear structures of the human temporal bone, we used a clinically more practical method to obtain results through the intact auditory meatus. We used a laser intensity of less than 1 mW. The measurements were performed in a room with unlimited sound transmission of frequencies between 0.5 and 8 kHz. The signals from the vibration of the tympanic membrane, obtained by this touch-free method, were analyzed by Fourier transform, showing only the fundamental oscillation but not the higher harmonics. Experimental data on middle ear effusions, obtained by fixation of the malleus head and by drilling the temporal bone, are presented.