Application of holographic interferometry to the study of hearing: analysis of the human skull bone vibration (author's transl)

Abstract

Vibration of the human skull bone was observed by means of the holographic interferometry.Holography is a new optical technique which is originally being applied to the transmission and the management of the image-information. Holographic interferometry, an application of holographic technique, is an unique and useful method for analysis of vibration, in which the human skull bone vibration was analyzed three-dimensionally. Three human dry skull bones were used, and the results are as follows;1) Number of the first proper vibration of the skull bones, whose sutures were filled with Alon alpha, ranged between 1700 and 2100Hz. The proper vibration numbers of the higher degrees were also observed.2) At each proper vibration number, the skull bone vibrated greatly on the bilateral temporal regions and vibrated less on the median region. This mode was common on the other proper vibration numbers of the higher degrees. The distortion of the skull bone was estimated as about 10-7cm at 0dB.3) It is known that the inertia bone conduction acts a great part on the low frequency. Through this research, however, the possibility of the compressive bone conduction was considered even in the low frequencies.