The Woodruff School

SUMMARY

The mammalian ear acts as an impressively sensitive broadband receiver which transduces sound waves in the ear canal to electrical signals sent to the nervous system. By studying the mechanics of different components of the ear, the mechanisms which allow for such remarkable abilities can be better understood and the treatment and prevention of hearing loss can be improved. A more complete understanding of the mechanics of the tectorial membrane (an important structure within the inner ear) and the middle ear would contribute to a better understanding of overall hearing function.

In recent years, examination of cochlear physiology in genetically modified mice has demonstrated that the mutation of genes affecting tectorial membrane proteins causes changes in key characteristics of cochlear function. In the past decade, several groups have measured wave propagation on isolated tectorial membrane segments. The presence of collagen fibers within the tectorial membrane causes the tectorial membrane to be strongly anisotropic. A computational model is used in order to determine the effects of anisotropy on wave propagation along the tectorial membrane segments and an inverse methodology is proposed in order to determine accurate estimations of the tectorial membrane mechanical properties of wild-type and mutant mice.

The middle ear efficiently transmits sound from the ear canal into the inner ear through a broad range of frequencies: understanding middle-ear transmission characteristics is essential in the study of hearing mechanics. In preliminary work, middle-ear transmission characteristics were examined using a circuit model of the chinchilla middle ear. The eardrum was found to play a large role in middle-ear transmission at high frequencies. The development and analysis of a computational model of the amphibian eardrum, whose flat and nearly circular geometry make it a simpler structure than the mammalian eardrum, is proposed in order to further investigate the transmission characteristics of the eardrum.

SUBJECT:	Ph.D. Proposal Presentation

BY:	Charlise Lemons

TIME:	Monday, December 5, 2016, 11:00 a.m.

PLACE:	MRDC Building, 4211

TITLE:	Examining Middle-ear and Tectorial Membrane Mechanics using Analytical and Computational Models

COMMITTEE:	Dr. Julien Meaud, Chair (ME) Dr. Alper Erturk (ME) Dr. Karim Sabra (ME) Dr. Kenneth Cunefare (ME) Dr. Wei Sun (BME)

SUMMARY The mammalian ear acts as an impressively sensitive broadband receiver which transduces sound waves in the ear canal to electrical signals sent to the nervous system. By studying the mechanics of different components of the ear, the mechanisms which allow for such remarkable abilities can be better understood and the treatment and prevention of hearing loss can be improved. A more complete understanding of the mechanics of the tectorial membrane (an important structure within the inner ear) and the middle ear would contribute to a better understanding of overall hearing function. In recent years, examination of cochlear physiology in genetically modified mice has demonstrated that the mutation of genes affecting tectorial membrane proteins causes changes in key characteristics of cochlear function. In the past decade, several groups have measured wave propagation on isolated tectorial membrane segments. The presence of collagen fibers within the tectorial membrane causes the tectorial membrane to be strongly anisotropic. A computational model is used in order to determine the effects of anisotropy on wave propagation along the tectorial membrane segments and an inverse methodology is proposed in order to determine accurate estimations of the tectorial membrane mechanical properties of wild-type and mutant mice. The middle ear efficiently transmits sound from the ear canal into the inner ear through a broad range of frequencies: understanding middle-ear transmission characteristics is essential in the study of hearing mechanics. In preliminary work, middle-ear transmission characteristics were examined using a circuit model of the chinchilla middle ear. The eardrum was found to play a large role in middle-ear transmission at high frequencies. The development and analysis of a computational model of the amphibian eardrum, whose flat and nearly circular geometry make it a simpler structure than the mammalian eardrum, is proposed in order to further investigate the transmission characteristics of the eardrum.