Page 34 - Fall2020

BIOMECHANICS OF THE MIDDLE EAR
via air conduction through the middle ear. Sound can also reach the cochlea via bone-conduction pathways, in which the middle ear also plays an important role (Stenfelt, 2013).
Otologists often perform surgery to restore function in damaged or diseased middle ears, such as patching a damaged eardrum, replacing an eroded incus with a prosthesis, or bypassing a stapes immobilized by otoscle- rotic bone growth with a prosthesis inserted into a hole in the footplate (Merchant and Rosowski, 2013). Before surgery can be performed, however, a proper diagnosis has to be made. The noninvasive diagnosis of middle ear pathologies is an important area of clinical research, particularly in the case of newborns because they cannot participate in standard clinical tests (Keefe et al., 2012). Surgery is more common in patients with middle ear pathologies. For patients with cochlear damage, a clini- cian will typically prescribe an acoustic hearing aid to provide amplified sound. However, a number of groups have been developing implantable hearing aids that amplify sound by mechanically vibrating the ossicles. A major advantage of these devices is reduced feedback, which allows greater amplification and wider bandwidth. Although these new devices cost more than traditional acoustic hearing aids, they can enable improved sound quality and better hearing in noisy environments (Puria, 2013). A nonimplantable alternative has also been devel- oped that contacts the eardrum from the ear canal side and mechanically vibrates the malleus (Puria, 2013).
Conclusions
Like a trusty sailboat with a seasoned captain, the mam- malian middle ear is able to navigate through a sea of complexity to provide a smooth and graceful experience of the environment. And much as a small, nimble craft must adapt to the perils of seafaring in different ways than a larger, more robust ship, the middle ear too has evolved in clever ways to suit the needs of different species. Although a multitude of vibration modes on the eardrum and many varied motions of the ossicles are involved in this voyage, the middle ear reveals none of these secrets until we get on board and examine it using modern measurement tools and computational approaches. Finally, by straddling the worlds of acoustics, mechanics, materials science, fluid mechanics, biology, medicine, computational modeling, and technology, the middle ear provides an ideal play- ground for an interdisciplinary crew of adventure-seeking collaborative researchers.
Acknowledgments
Some of my work described here has been funded by the National Institute on Deafness and Communication Dis- orders, National Institutes of Health, and, more recently, by the Amelia Peabody Charitable Fund. I am grateful to the entire OtoBiomechanics Group at the Eaton-Pea- body Laboratories and particularly Kevin N. O’Connor for assistance on multiple levels.
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