Vibration measurement of the human tympanic membrane--in vivo

The vibration patterns of the human eardrum in vivo have been recorded by time average electronic speckle pattern interferometry--ESPI. The necessary stability was achieved by shortening the exposure time of each TV frame. The amplitude--and phasedistribution was mapped across the drum by phase-modulation techniques which also could show the vibrations in slow motion. By photoelectric detection of the TV image intensity, amplitudes down to 2 nm could be measured. Preliminary results are presented.