Human middle-ear imaging, physiology, and biomechanics
Principal Investigator: CHARLES RICHARD STEELE
Abstract: DESCRIPTION (provided by applicant): The middle ear plays a vital role in the sense and sensitivity of hearing, yet there is currently a lack of knowledge about the mechanisms of high-frequency middle-ear sound transmission in mammals. The overall goal of this project is to understand the relationships between the morphometry of the middle ear and the biomechanical processes that lead to physiological and clinical responses. The approach is to deconstruct the middle ear into subsystems that are each characterized by morphological and physiological measurements, as well as three-dimensional linear and nonlinear mathematical analyses. The subsystems are then mathematically reassembled to form a complete `virtual middle-ear'model that can be used to examine issues relevant to high frequency sound transmission in a variety of animals and repaired middle ears before and after surgery. Specific Aim #1: At high frequencies, experimental evidence suggests that sound conduction is not limited by the inertia of the middle-ear bones, contrary to expectations. Recent moment of inertia calculations suggest that the malleus switches from a hinging motion at low frequencies to a new twisting motion at high frequencies, in order to take advantage of the reduced inertia associated with a twisting type of motion. It is hypothesized that the mobile saddle-shaped malleus-incus joint is able to suitably transfer this twisting motion to the incus. This will be tested using micro-CT imaging, cryogenic transmission electron microscopy, optical second harmonic generation, hinging and twisting motion measurements with a laser Doppler vibrometer, and bio-computational modeling. Specific Aim #2: The human middle-ear cavity is known to be an irregularly shaped space within the temporal bone that varies from person to person. A finite element modeling approach will be used to test the hypothesis that the complex shape of the human middle-ear cavity functions to break up resonant modes that would otherwise decrease hearing sensitivity at specific resonant frequencies. The finite element approach, which is well-suited for the nonlinear descriptions needed to incorporate the forces exerted by the tensor tympani and the stapedius muscles, will also be used to understand how these muscles affect sound transmission through the middle ear. Specific Aim #3: Ear surgeons target restoration of hearing in the speech frequency range, and not in the higher frequencies where important sound localization cues are known to reside. Temporal bone measurements and the anatomically- and physics-based virtual middle-ear model will be used to understand how to improve high-frequency outcomes of middle-ear surgical treatments, such as tympanic membrane repair (myringoplasty) and ossicle replacement with a prosthesis (tympanoplasty). Specific Aim #4: Our hypothesis that myringoplasty and tympanoplasty surgery patients continue to have air-bone gap deficits at frequencies above 4 kHz will be tested. New methods to measure bone conduction sensitivity will be developed for high frequencies and combined with existing air conduction measurement methods. While it is well accepted that amongst terrestrial vertebrates, the mammalian middle ear is unique in its ability to transmit sounds from the external world to the cochlea for frequencies above 10 kHz, the biomechanical basis for sound transmission at high frequencies is poorly understood, which has consequences in the clinical realm. It is well known that the morphometry of the middle ear plays a key role in sound transmission, but the lack of knowledge about the relationships between middle-ear structures and sound transmission has resulted in unsatisfactory and variable outcomes of middle-ear repairs, particularly at high frequencies where sound localization cues may be important for hearing in noisy situations. The proposed studies will provide a solid scientific foundation for understanding the structural basis of middle-ear sound transmission, leading to clinical applications for the surgical reconstruction of the middle ear, the interpretation of otoacoustic emissions, and improvements to the understanding of passive and active prostheses used by surgeons to repair the middle ear.
Funding Period: 2009-02-17 - 2014-01-31
more information: NIH RePORT
- Middle ear cavity and ear canal pressure-driven stapes velocity responses in human cadaveric temporal bonesKevin N O'Connor
Department of Otolaryngology Head and Neck Surgery, Stanford University, 300 Pasteur Drive, Stanford, California 94305, USA
J Acoust Soc Am 120:1517-28. 2006..3 vs -6.7 dB/octave for Aibara et al., Hear. Res. 152, 100-109 (2001)], and significantly more phase group delay (134 vs 62 micros for Aibara et al.)...
- Superior-semicircular-canal dehiscence: effects of location, shape, and size on sound conductionNamkeun Kim
Department of Mechanical Engineering, Stanford University, 496 Lomita Mall, Stanford, CA 94305, USA
Hear Res 301:72-84. 2013..This article is part of a special issue entitled "MEMRO 2012"...
- Békésy's contributions to our present understanding of sound conduction to the inner earSunil Puria
Department of Mechanical Engineering, Stanford University, Durand Building, 496 Lomita Mall, Stanford, CA 94305, USA
Hear Res 293:21-30. 2012..Today many of Békésy's ideas continue to be investigated and extended, some have been supported by new evidence, some have been refuted, while others remain to be tested...
- Comparisons of electromagnetic and piezoelectric floating-mass transducers in human cadaveric temporal bonesIl Yong Park
Department of Biomedical Engineering, College of Medicine, Dankook University, Cheonan, Republic of Korea
Hear Res 272:187-92. 2011..Thus, it is expected that the PFMT can be utilized to compensate for high-frequency sensorineural hearing loss...
- The floating mass transducer on the round window versus attachment to an ossicular replacement prosthesisYoshitaka Shimizu
Department of Veterans Affairs, Palo Alto Health Care System, Palo Alto, California, USA
Otol Neurotol 32:98-103. 2011..The goal is to provide efficient transfer of sound vibration into the cochlea. The hypothesis is that the FMT location on the prosthesis is superior to the RW location...
- Middle-ear function at high frequencies quantified with advanced bone-conduction measuresGerald R Popelka
Department of Otolaryngology, Stanford University, 801 Welch Road, Stanford, CA 94305 5739, USA
Hear Res 263:85-92. 2010....
- Tympanic-membrane and malleus-incus-complex co-adaptations for high-frequency hearing in mammalsSunil Puria
Department of Mechanical Engineering, 496 Lomita Mall, Stanford, CA 94305, USA
Hear Res 263:183-90. 2010..This work argues that the upper-frequency hearing limit of a given mammalian species can in part be understood in terms of morphological co-adaptations of the eardrum and ossicular chain...
- Ossicular resonance modes of the human middle ear for bone and air conductionKenji Homma
Adaptive Technologies, Inc, Blacksburg, Virginia 24060, USA
J Acoust Soc Am 125:968-79. 2009..The finding is also consistent with the hypothesis that a middle-ear structural resonance is responsible for the prominent peak seen at 1.5-2 kHz in BC limit data...
- Finite element modeling of acousto-mechanical coupling in the cat middle earJAMES P TUCK-LEE
Department of Mechanical Engineering, Stanford University Stanford, California 94305, USA
J Acoust Soc Am 124:348-62. 2008....
- Soft tissue morphometry of the malleus-incus complex from micro-CT imagingJae Hoon Sim
Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA
J Assoc Res Otolaryngol 9:5-21. 2008..The micro-CT imaging modality is a nondestructive and relatively fast method for obtaining soft tissue morphometry and provides accurate anatomical features in relation to the principal axes of bones...
- The discordant eardrumJonathan P Fay
Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA
Proc Natl Acad Sci U S A 103:19743-8. 2006..In each case, the peculiar properties of the eardrum are directly responsible for the optimal sensitivity of this discordant drum...
- Morphometric and physiologic analyses of the mammalian low frequency sound localiARMIN HARRY SEIDL; Fiscal Year: 2013..Understanding this mechanism will provide a solid foundation to better understand hearing disabilities and will assist in finding ways to solve hearing related health issues. ..
- UNDERSTANDING OTOACOUSTIC EMISSIONSChristopher A Shera; Fiscal Year: 2013..abstract_text> ..