“…Because the experiment 14 started at 630 Hz, it needed to clarify how the temporal bone support in the presented model affected the OC vibration at lower frequencies. The effect of bone fixation was visible as differences between the experimental CP velocities obtained from studies on human heads 23 and the RW edge vibration velocities at low frequencies (Fig. 8 ).…”
Section: Discussionmentioning
confidence: 98%
“… Figure 8 The averaged round window edge velocity in the direction perpendicular to the round window. Four directions of bone conduction stimulation compared with the cochlear promontory vibration measured on cadavers for the same stimulation site above the lateral semicircular canal (LSCC) 23 . The forces in the presented finite element model tuned to the values generated in the experiment by the B81 transducer.…”
Section: Discussionmentioning
confidence: 99%
“…The BM vibration depends on the pressure difference between the scala tympani and the scala vestibule, which is measurable on cadavers 22 . There are measurement inaccuracies for BC stimulation due to relative movements between pressure gauges and vibrating bone 23 . Kim et al 24 numerically modeled the influence of excitation direction on the BM velocity.…”
Sound transmission to the human inner ear by bone conduction pathway with an implant attached to the otic capsule is a specific case where the cochlear response depends on the direction of the stimulating force. A finite element model of the temporal bone with the inner ear, no middle and outer ear structures, and an immobilized stapes footplate was used to assess the directional sensitivity of the cochlea. A concentrated mass represented the bone conduction implant. The harmonic analysis included seventeen frequencies within the hearing range and a full range of excitation directions. Two assessment criteria included: (1) bone vibrations of the round window edge in the direction perpendicular to its surface and (2) the fluid volume displacement of the round window membrane. The direction of maximum bone vibration at the round window edge was perpendicular to the round window. The maximum fluid volume displacement direction was nearly perpendicular to the modiolus axis, almost tangent to the stapes footplate, and inclined slightly to the round window. The direction perpendicular to the stapes footplate resulted in small cochlear responses for both criteria. A key factor responsible for directional sensitivity was the small distance of the excitation point from the cochlea.
“…Because the experiment 14 started at 630 Hz, it needed to clarify how the temporal bone support in the presented model affected the OC vibration at lower frequencies. The effect of bone fixation was visible as differences between the experimental CP velocities obtained from studies on human heads 23 and the RW edge vibration velocities at low frequencies (Fig. 8 ).…”
Section: Discussionmentioning
confidence: 98%
“… Figure 8 The averaged round window edge velocity in the direction perpendicular to the round window. Four directions of bone conduction stimulation compared with the cochlear promontory vibration measured on cadavers for the same stimulation site above the lateral semicircular canal (LSCC) 23 . The forces in the presented finite element model tuned to the values generated in the experiment by the B81 transducer.…”
Section: Discussionmentioning
confidence: 99%
“…The BM vibration depends on the pressure difference between the scala tympani and the scala vestibule, which is measurable on cadavers 22 . There are measurement inaccuracies for BC stimulation due to relative movements between pressure gauges and vibrating bone 23 . Kim et al 24 numerically modeled the influence of excitation direction on the BM velocity.…”
Sound transmission to the human inner ear by bone conduction pathway with an implant attached to the otic capsule is a specific case where the cochlear response depends on the direction of the stimulating force. A finite element model of the temporal bone with the inner ear, no middle and outer ear structures, and an immobilized stapes footplate was used to assess the directional sensitivity of the cochlea. A concentrated mass represented the bone conduction implant. The harmonic analysis included seventeen frequencies within the hearing range and a full range of excitation directions. Two assessment criteria included: (1) bone vibrations of the round window edge in the direction perpendicular to its surface and (2) the fluid volume displacement of the round window membrane. The direction of maximum bone vibration at the round window edge was perpendicular to the round window. The maximum fluid volume displacement direction was nearly perpendicular to the modiolus axis, almost tangent to the stapes footplate, and inclined slightly to the round window. The direction perpendicular to the stapes footplate resulted in small cochlear responses for both criteria. A key factor responsible for directional sensitivity was the small distance of the excitation point from the cochlea.
“…The differential intracochlear pressure is the measurement technique closest to the organ of Corti. Also, it includes the contributions of all five bone conduction pathways, and previous measurements indicate that it is the most reliable indicator of loudness perception ( Borgers et al, 2019 ; Putzeys et al, 2022 ; Felix et al, 2023 ). Therefore, we can conclude that evaluating the loudness perception with the ear canal pressure or promontory velocity introduces a significant 6–7 dB difference, which is larger than the standard deviation in pure tone audiometry ( Jerlvall et al, 1983 ) and the test–retest variability of the individual measures as shown in Supplementary Figure S40 .…”
The study evaluates the accuracy of predicting intracochlear pressure during bone conduction stimulation using promontory velocity and ear canal pressure, as less invasive alternatives to intracochlear pressure. Stimulating with a percutaneous bone conduction device implanted in six human cadaveric ears, measurements were taken across various intensities, frequencies, and stimulation positions. Results indicate that intracochlear pressure linearly correlates with ear canal pressure (R2 = 0.43, RMSE = 6.85 dB), and promontory velocity (R2 = 0.47, RMSE = 6.60 dB). Normalizing data to mitigate the influence of stimulation position leads to a substantial improvement in these correlations. R2 values increased substantially to 0.93 for both the ear canal pressure and the promontory velocity, with RMSE reduced considerably to 2.02 (for ear canal pressure) and 1.94 dB (for promontory velocity). Conclusively, both ear canal pressure and promontory velocity showed potential in predicting intracochlear pressure and the prediction accuracy notably enhanced when accounting for stimulation position. Ultimately, these findings advocate for the continued use of intracochlear pressure measurements to evaluate future bone conduction devices and illuminate the role of stimulation position in influencing the dynamics of bone conduction pathways.
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