Measuring the motions in the human middle ear by Laser Doppler Vibrometry

For the detection of tiny motions which are caused by the tympanic membrane under normal hearing conditions, the touch-free method of Laser Doppler Vibrometry was used. Spectra containing information about the motions of the middle ear bones were recorded within 1 min when the umbo was chosen as the detection point and acoustic stimulation was performed via white noise excitation. It was observed that these spectra correlate to middle ear diseases, which had been artificially induced by manipulations in the chain of the middle ear bones in human temporal bones. The dosimetry of the applied laser radiation was found to be harmless to the tympanic membrane, which opened the way for successful in vivo measurements.