Computerized analysis of moiré contours applied to eardrum shape measurements

Khanna and Tonndorf have used moire topography to study the resting shape of the eardrum and the effects of static pressures [J. Acoust. Soc. Am. 57, S72 (1975} and 58, S88 (1975)]. They have recently modified their apparatus so as to remove the parallel grating image that had been superimposed on the moire isotathmic (constant‐depth) contours. By simplifying the pattern recognition problem, this has made it feasible to develop a semiautomatic method of analyzing the data. An interactive computerized image‐processing system is used to identify and extract the contours from the photographic image. An interactive computer‐graphics system is then used for computing shape profiles, volumes, static displacements, etc. and for preparing the shape data for use in a finite‐element model of the eardrum. [Work supported by Medical Research Council of Canada and Macdonald Stewart Foundation.]