Julien Meaud

Mechanics of Hearing Discussion Moderated by Gabrielle Merchant, Yi-Wen Liu and George Burwood and related to sessions 13, 14 and 15: Machine Learning, Cochlear Nonlinearity, Otoacoustic Emissions and Keynote

Mechanics of Hearing Discussion Moderated by Heidi Nakajima, Jeffrey Tao Cheng and Alessandro Altoè related to session 10: Human cochlear mechanics, session 11: Middle ear: prosthesis and session 12: Cochlear modeling.

Mechanics of Hearing Discussion Moderated by Heidi Nakajima, Jeffrey Tao Cheng and Alessandro Altoè related to session 10: Human cochlear mechanics, session 11: Middle ear: prosthesis and session 12: Cochlear modeling.

Mechanics of Hearing Discussion Moderated by Brian Frost and Yanli Wang related to sessions 8: Cochlear micromechanics – models and 9: Prestin and tip-link mechanics

Mechanics of Hearing Discussion Moderated by Gabrielle Merchant, Yi-Wen Liu and George Burwood and related to sessions 13, 14 and 15: Machine Learning, Cochlear Nonlinearity, Otoacoustic Emissions and Keynote

Mechanics of Hearing Discussion Moderated by Brian Frost and Yanli Wang related to sessions 8: Cochlear micromechanics – models and 9: Prestin and tip-link mechanics

Mechanics of Hearing Discussion Moderated by Manuela Nowotny and James Dewey related to sessions 16 and 17: Comparative Mechanics and Cochlear Mechanics Experiments

Mechanics of Hearing Discussion Moderated by Manuela Nowotny and James Dewey related to sessions 16 and 17: Comparative Mechanics and Cochlear Mechanics Experiments

In vivo measurements show that the basilar membrane (BM) exhibits sharp frequency tuning and high sensitivity to low-level stimuli. This has led most cochlear theories to assume that outer hair cells (OHCs) amplify traveling waves by delivering power directly to the BM. However, recent experiments revealed that the main bodies of Deiters cells (DCs), which are sandwiched between the OHCs and the BM, deform significantly in response to acoustic inputs. These findings challenge the hypothesis that power is transmitted by OHCs to the BM through the DCs. In this work, we consider a cochlear model that includes a micromechanical model of the organ of Corti with deformable DCs. The micromechanical model includes not only the BM, OHCs and DCs, but also other components of the organ of Corti, including the reticular lamina (RL) and pillar cells (PCs). We find that the amplitude and phase of the OHC-DC junction is consistent with in vivo measurements only if (1) the DC stiffness is comparable to that of OHCs; and (2) the joint between the RL and PCs is relatively stiff. Under these conditions, the model predicts that OHC electromotility does not deliver power to the BM through the classical OHC-DC-BM pathway, but rather through an alternative pathway through the RL and PCs. This result points to a new theoretical framework in which the RL and PCs, rather than DCs, serve as the primary conduit for the transfer of OHC-generated power to the BM and offers new insight into how the cochlea may achieve its remarkable sensitivity and frequency selectivity.

Mechanics of Hearing Discussion Moderated by Anthony Peng, Renata Sisto, Sebastiaan Meenderink, Jong-Hoon Nam and related to sessions 4-7: Hair bundle mechanics II, Nonlinear dynamics of the cochlea, Cochlear processing, and Cochlear mechanics: methods and results.

Mechanics of Hearing Discussion Moderated by Ernst Dalhoff, Dáibhid Ó Maoiléidigh and Susan Voss and related to sessions 1, 2 and 3: External and middle ear, Hair bundle I and Otoacoustic emissions.

Mechanics of Hearing Discussion Moderated by Anthony Peng, Renata Sisto, Sebastiaan Meenderink, Jong-Hoon Nam and related to sessions 4-7: Hair bundle mechanics II, Nonlinear dynamics of the cochlea, Cochlear processing, and Cochlear mechanics: methods and results.

Mechanics of Hearing Discussion Moderated by Ernst Dalhoff, Dáibhid Ó Maoiléidigh and Susan Voss and related to sessions 1, 2 and 3: External and middle ear, Hair bundle I and Otoacoustic emissions.

Abstract This article studies the nonreciprocity of a system that consists of a bistable element coupled to a monostable element through a contactless magnetic interaction. To illustrate the concept, the bistable element is physically realized using a pendulum that interacts with a stationary magnet and the monostable element is a classical pendulum. A numerical model is implemented to simulate the nonlinear dynamics of the system. Both simulations and experiments show that the system exhibits a strong amplitude-dependent nonreciprocity in response to initial excitations. At small input amplitudes, the system has an intrawell response with minimal transmission of energy whether the excitation is exerted on the side of the bistable pendulum or on the other side. However, at high input amplitude, a strong nonreciprocal behavior is observed: excitation of the bistable pendulum causes an interwell response which considerably reduces the distance between the two pendulums and allows energy to be efficiently transmitted through the contactless magnetic interaction; excitation of the monostable pendulum does not cause any interwell response and results in limited energy transmission. The combination of bistability and contactless nonlinear interactions allows the system to exhibit very strong amplitude-dependent nonreciprocity, which may be useful in a wide range of applications.

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Julien Meaud, Haiqi Wen, George Samaras, Yiwei Xia; Modeling the fine structure of ear canal pressure and cochlear microphonics in response to a pure tone. AIP Conf. Proc. 27 February 2024; 3062 (1): 030001. https://doi.org/10.1063/5.0189201 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search

Based on a plethora of basilar membrane vibration measurements, it had been presumed that cochlear nonlinearity due to outer hair cell (OHC) forces is limited to the peak region of a given stimulus. However, recent experiments showing two-tone suppression of the reticular lamina (RL) indicate that OHCs provide electromotile feedback over a much broader basal region. In this work, a computational model of the cochlea containing organ of Corti (OoC) structures, a fluid domain coupled to the basilar membrane (BM), and an electrical model to represent OHC activity is calibrated to experimental data for the mechanical and electrical responses to a pure tone and then used to make two-tone suppression predictions. These predictions are in line with recent experimental measurements, capturing extended nonlinearity in the RL response compared to that of the BM. By comparing the OHC force of pure tone and two-tone model predictions, we examine the root cause of broader nonlinearity seen in the response of OoC structures at the top end of the OHCs.

Stimulus frequency otoacoustic emissions (SFOAEs), which are sounds emitted by the cochlea at the frequency of the stimulus, have been used as a noninvasive measure of cochlear function. The gradient of the SFOAE phases characterizes the latency of emission and is associated with the frequency selectivity and sharpness of tuning of the mammalian cochlea. However, whether the phase-gradient delay of SFOAE can be used as a indicator of cochlear tuning and sensitivity reliably when the proper-ties of the cochlea change remains unclear. The objective of this study is to address this question by varying cochlear model activity, tectorial membrane (TM) properties and organ of Corti (OoC) micromechanical properties to change cochlear tuning. In this work, a three-dimensional gerbil cochlear model that couples mechanical, electrical and acoustic domains with cochlear roughness has been used. The roughness is implemented on outer hair cells (OHCs) force acting on the basilar membrane (BM). Parameters that control the activity levels, TM longitudinal coupling and OoC impedance are varied. The results show that changes in sharpness of tuning due to reduction in cochlear activity and TM longitudinal coupling can be detected by using SFOAE phase-gradient delay. However, changes in cochlear tuning due to changes in OoC impedance are not necessarily reflected by corresponding changes in SFOAE phase-gradient delay.

According to the Center for Disease Control, hearing loss is the third most common chronic physical condition in the US, and it is more prevalent than diabetes or cancer. Most cases of the permanent hearing loss results from damage to the sensory cells of the inner ear. These sensory hair cells (called outer hair cells) provide us with sensitive hearing through a delicate process of amplification of the sound-evoked motions of the inner ear epithelia.

Spontaneous otoacoustic emissions (SOAEs) are sounds generated by the inner ear in the absence of an external stimulus and are a direct consequence of the inner ear nonlinearity that arises from hair cell electromechanics. SOAEs with similar spectral characteristics have been observed in both mammals and non-mammalian species such as lizards, suggesting a common mechanism in their generation, despite striking differences in inner ear physiology between mammals and non-mammals. In this work, a model based on coupled limit-cycle oscillators (Vilfan and Duke, Biophys. J, vol. 95, pp. 4622–4630, 2008) and a model based on standing waves (Bowling etal., Sci. Rep., vol. 11, pp. 1–14, 2021) are implemented to analyze their ability to predict key SOAE characteristics. As in experiments, the models predict discrete peaks in the SOAEs with quasi-periodic spacing. However, if noise is neglected, the SOAE peaks are unrealistically sharp. In this work, the effect of noise on SOAE spectral properties (e.g., bandwidth of SOAE peaks) and statistical properties (e.g., interpeak cross-correlations) is evaluated to assess whether either model is a better representation of SOAE generation. This is a key step in understanding the theoretical underpinnings of SOAE generation. [Research funded by NIH grant R01 DC016114.]