Abstract: Under hearing conditions, the amplitude of the motion of the human tympanic membrane is in the range of several tens of nanometers. To measure motions of this size by a touchfree method is a domain of laser technology. Here laser-Doppler-vibrometry was chosen because of its sensitivity in detecting small amplitudes and the clear information about the detected point on the tympanic membrane. Care was taken to develop the method for a clinically acceptable procedure for hearing diagnosis. The first realization by sinus wave excitation was found to be very time consuming. A measuring time of less than a minute was obtained by white noise excitation, fast Fourier transformation and choosing the umbo as the detection point. Meanwhile the setup is used for in vivo measurements. !14
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