Three-dimensional laser Doppler interferometric display of human tympanic membrane vibrations at two different frequencies and sound pressure levels.

The vibrational movements of the tympanic membrane of human in vitro specimens were studied by computerized laser Doppler interferometry. The entire surface of the vibrating tympanic membrane was scanned with the laser beam and all information was stored digitally making it possible to recreate the movements as in slow motion on the oscilloscope. Single phases of interest from the vibrational cycle were plotted as shown. The resonance patterns at 0.58 kHz and 3.11 kHz are compared and the effect of different sound pressure levels on the vibrational movement of the tympanic membrane demonstrated.