A mechanical model of the middle ear is obtained from anatomical observations. The differential equations for the model are solved, and the solutions are found in good agreement with the impedance of the ear at the tympanic membrane measured in many earn of fresh cadavers. Thus, the mechanism of the middle ear is clarified theoretically as well as experimentally. The ossicular chain loaded with the impedance of the cochlea is found to be the most important factor controlling the impedance of the tympanic membrane. The ossicular chain has two resonances: the lower one due to the malleoincudal body, and the higher due to the stapes. Thus, the ossicular chain keeps the reactance of the tympanic membrane near or at its resonances. The function of the air cavities behind the tympanic membrane is found to be similar to but less than that of the ossicular chain. The apparent pressure gain by the middle ear for the cochlea is measured. From these data the frequency characteristic of the ossicular chain the impedance of the stapes are calculated. Moreover, it is found experimentally as well as theoretically that the transmission of the middle ear is not only increased by a lower impedance of the tympanic membrane but also by a higher impedance; transmission is increased by the tympanic membrane vibrating as a rigid cone attached to the ossicular chain even though such attachment increases the impedance of the tympanic membrane.
No takes yet. Share an insight, caveat, or question.
Y Onchi (1961) studied this question.