4pPP5. Middle ear of a lion: Comparison of structure and function to domestic cat.

Session: Thursday Afternoon, May 16

Author: Gregory T. Huang
Author: John J. Rosowski
Author: Deborah T. Flandermeyer
Author: William T. Peake
Location: Dept. of Elec. Eng. and Comp. Sci. and Res. Lab. of Elec., MIT, Cambridge, MA 02139
Location: Eaton-Peabody Lab., Mass. Eye and Ear Infirmary, 243 Charles St., Boston, MA 02114


Acoustic and anatomical measurements have been made in a deceased lion (Panthera leo) and compared to measurements in domestic cat (Felis catus). The results are used to test a model in which the acoustic impedance at the tympanic membrane (TM) is the sum of (1) the impedance of the TM and ossicular chain and (2) the impedance of the middle-ear cavities. Impedance was measured at the TM in lion before and after manipulation of the cavity structures; sound pressure in the cavities was measured simultaneously. CT sections of the lion middle ear were used to reconstruct the tympanic ring, the tympanic cavity, the bullar cavity, and the foramen that connects these cavities. A quantitative comparison of these structures shows that ear dimensions in the lion are roughly two times those in cats. Acoustic measurements in the lion and cat are qualitatively similar, but the lion middle-ear impedance is generally smaller. A six-element analog circuit model captures the main features of both sets of measurements. The acoustic effects of the size differences are represented by changes in the circuit model element values. In its ear, the lion is just a big pussycat. [Work supported by NIDCD.]

from ASA 131st Meeting, Indianapolis, May 1996