Vibrational Holography of the Tympanic Membrane: Further Findings

Publisher Website
Google Scholar
Abstract
At the 78th Meeting, photographs of the vibratory pattern of the tympanic membrane were presented [Khanna et al., Tonndorf and Khanna]. They were obtained with the aid of time-averaged holography from cadaver ears of cat and man. These findings, which are compatible with the catenary principle of tympanic membrane action as postulated by Helmholtz (1868), need further elaboration. With frequency above 2000 Hz, the patterns become gradually restricted in area and subdivide into multiple quasi-independent subpatterns. Volume displacements for constant SPLs calculated from such photographs decrease with frequency in a similar manner and were found to be in excellent numerical agreement with such values calculated from available impedance data obtained in living animals or human subjects. This latter agreement (1) justified the use of cadaver material in the present experiments and (2) shows that the multiple subpatterns at higher frequencies are still in phase over the entire surface of the tympanic membrane. (Time-averaged holography is not sensitive to phase.) A revised formulation of the total middle-ear transformer ratio, which includes the catenary effect, is presented. [Supported by NIH grants.]

This publication has 0 references indexed in Scilit: