Ossicular Mechanics of a Low Frequency Ear and Implications for Bone-Conducted Hearing.

低频耳的听骨力学及其对骨传导听力的影响。

• 批准号: 10594482
• 负责人: Caitlin O'Connell-Rodwell
• 金额: $ 14.18万
• 依托单位: MASSACHUSETTS EYE AND EAR INFIRMARY
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-04-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10594482
• 关键词: 3-Dimensional; Affect; Air; Anatomy; Articulation; Auricular prosthesis; Bone Conduction; Characteristics; Cochlea; Detection; Drowning; Ear; Elephants; Exhibits; External auditory canal; Food; Frequencies; Goals; Head Movements; Hearing; Hearing Aids; Hearing Tests; Human; Image; Impulsivity; Incus; Investigation; Jaw; Joints; Labyrinth; Lasers; Malleus; Mammals; Mastication; Measurement; Measures; Mechanics; Methods; Modeling; Modification; Morphology; Motion; Noise; Ossicular Replacement Prosthesis; Performance; Play; Promontory; Prosthesis; Role; Rotation; Series; Shapes; Source; Stapes; Structure-Activity Relationship; Temporal bone structure; Testing; Time; Tympanic membrane; animation; bone; comparative; cranium; design; flexibility; hearing impairment; improved; insight; middle ear; novel; pressure; reconstruction; response; sound; sound frequency; structural determinants; transmission process; vibration

Abstract The mammalian ear contains three middle-ear bones called ossicles that transmit both air-conducted (AC) sound from the eardrum to the inner ear and bone-conducted (BC) vibrations of the skull to the inner ear. The functional significance of having three ossicles to transmit sound is not completely understood, yet their varied shapes, mass distributions, and articulation around two flexible joints could serve to protect the inner ear from static pressure and impulsive AC sounds presented in the ear canal, and could reduce sensitivity to potentially distracting self-generated BC vibrations caused by head movement, chewing, etc. At the same time, ossicles might also improve AC and BC hearing at low frequencies. In this study, we propose to test the role that ossicular shape, mass and mass distribution, as well as flexibility play on 3D ossicular motion and sound transmission into the cochlea for both human and elephant temporal bones in response to AC and BC stimulation under normal and modified conditions. Despite significant anatomical differences, humans and elephants exhibit very similar audiograms over their overlapping 20 Hz–11 kHz frequency range, although elephants can hear below 20 Hz and humans can hear above 11 kHz. Middle-ear bones scale with skull size, such that elephant ossicles (the largest among terrestrial mammals) are approximately seven times heavier than those of humans. Studies suggest that BC hearing is enhanced below 100 Hz using mass-loading to simulate greater ossicular mass, and our preliminary measurements on elephants suggest that their heavier ossicles should yield an order of magnitude better BC hearing than humans at low frequencies. BC hearing in elephants might also be enhanced due to what appears to be a partially fused incudo-malleolar joint. Thus, quantifying the structure–function relationships and mass loading within human versus elephant ears could improve our understanding of the possible optimizations and trade-offs within the middle ear. The immediate goal of this investigation is to quantitatively compare human and elephant ossicular-chain morphology and motion as it relates to input to the cochlea by measuring ossicular shape and mass distributions using µCT imaging; and measuring 3D ossicular motions in response to AC and BC stimulation using 3D laser Doppler vibrometry, for the normal and modified cases with added mass and reduced ossicular-joint flexibility. The motion measurements will be used to animate µCT reconstructions of the ossicles, and these results will be compared using moments of inertia (MOI) to quantify the functional implications of the inter-species structural differences and effects of modifications in terms of: 1) sound transmission from the ear canal to the cochlea, especially at lower frequencies; 2) the relative motion of the ossicles; and 3) the transmission of sound via bone conduction. The structure–function relationships revealed through this inter-species comparison may have ramifications in the design of specialized passive and active middle-ear prosthetic devices for restoring human hearing.

抽象的 哺乳动物的耳朵包含三个称为小骨的中耳骨，可传输空气传导 (AC) 和空气传导 (AC) 的声音。 从鼓膜到内耳的声音以及从头骨到内耳的骨传导（BC）振动。 具有三个小骨来传输声音的功能意义尚不完全清楚，但它们的 不同的形状、质量分布和两个柔性关节周围的关节可以用来保护内部 耳朵免受耳道中出现的静压和脉冲交流声音的影响，并可能降低对耳道的敏感度 由头部运动、咀嚼等引起的潜在分散注意力的自生 BC 振动。 随着时间的推移，小骨也可能会改善低频的 AC 和 BC 听力。在这项研究中，我们建议测试一下。 听骨形状、质量和质量分布以及灵活性对 3D 听骨运动的作用 声音传输到人类和大象颞骨的耳蜗中以响应 AC 和 BC 尽管存在显着的解剖学差异，但人类和正常条件下的刺激。 大象在重叠的 20 Hz–11 kHz 频率范围内表现出非常相似的听力图，尽管 大象可以听到低于 20 Hz 的声音，而人类可以听到高于 11 kHz 的中耳骨比例与头骨大小， 大象的小骨（陆地哺乳动物中最大的）大约重七倍 研究表明，通过质量加载，BC 听力可在 100 Hz 以下得到增强。 模拟更大的听骨质量，我们对大象的初步测量表明，它们更重 小骨在低频下的 BC 听力应该比人类好一个数量级。 大象也可能由于部分融合的砧踝关节而得到增强。 量化人类与大象耳朵内的结构-功能关系和质量负载可以 提高我们对中耳内可能的优化和权衡的理解。 这项研究的目标是定量比较人类和大象的听骨链形态和 通过使用 µCT 测量听骨形状和质量分布，了解与耳蜗输入相关的运动 成像；并使用 3D 激光多普勒测量响应 AC 和 BC 刺激的 3D 听骨运动 振动测量，适用于质量增加和听骨关节灵活性降低的正常和改良病例。 运动测量将用于动画小骨的 µCT 重建，这些结果将 比较使用惯性矩（MOI）来量化物种间结构的功能影响 修改的差异和影响如下：1) 声音从耳道传输到耳蜗， 尤其是在较低频率下；2) 听小骨的相对运动；以及 3) 声音的传输； 通过这种种间比较揭示的结构-功能关系可能。 对用于恢复的专门被动和主动中耳假体装置的设计产生影响 人类的听觉。

项目成果

The impact of size on middle-ear sound transmission in elephants, the largest terrestrial mammal.

体型对最大陆地哺乳动物大象中耳声音传输的影响。

• 发表时间: 2024
• 影响因子: 3.7
• 作者: O'Connell;Berezin, Jodie L;Dharmarajan, Anbuselvan;Ravicz, Michael E;Hu, Yihan;Guan, Xiying;O'Connor, Kevin N;Puria, Sunil
• 通讯作者: Puria, Sunil