The middle ear of guinea pig has long been used for experimental studies. However, in spite of numerous otologic studies on guinea pig's middle ear, there are few investigations on measuring the size of each part of the middle ear. Therefore, in this study, a computer-aided 3-D reconstruction method was applied to the middle ear of a guinea pig, and the ossicles, tympanic membrane, ligaments and bulla were reconstructed three-dimensionally in detail. Then, the length, angle, volume and area of each part of the middle ear were obtained from these reconstructed images. Finally, the mechanism of the sound pressure enhancement in the middle ear was examined.
