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@PHDTHESIS{Kersten:1016952,
author = {Kersten, Simon},
othercontributors = {Vorländer, Michael and Epp, Bastian},
title = {{M}odeling and analysis of vibroacoustic mechanisms in
hearing},
school = {Rheinisch-Westfälische Technische Hochschule Aachen},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2025-07039},
series = {Aachener Beiträge zur Hörtechnik und Akustik},
pages = {1 Online-Ressource : Illustrationen},
year = {2025},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, Rheinisch-Westfälische Technische
Hochschule Aachen, 2025},
abstract = {Despite significant technological advancements in recent
decades, users of hearing aids and hearing protection often
report dissatisfaction due to an "unnatural" auditory
experience. These challenges highlight gaps in our
understanding of the physical mechanisms underlying hearing
– a complex vibroacoustic phenomenon involving
interactions between the sound field in the outer ear, the
mechanics of the middle ear, and the fluid dynamics of the
inner ear. Hearing not only involves the air conduction (AC)
pathway via the outer and middle ear, but also various bone
conduction (BC) pathways via which sound is transmitted to
the inner ear. BC hearing plays a crucial role in
audiological applications such as BC audiometry and BC
hearing aids, where vibrations are directly induced in the
skull. Another phenomenon involving both AC and BC is the
occlusion effect (OE): occluding the ear canal (EC) alters
own-voice perception, which is a major cause of the
dissatisfaction with hearing technologies. Experimentally
assessing the physics underlying hearing poses significant
ethical and technical difficulties. Therefore, modeling and
numerical simulations are essential tools for advancing our
understanding. These investigations also require examining
the vibroacoustic behavior of the inner ear, because it
serves as the sensor for all AC and BC pathways. Recent
studies challenge the classical view on inner ear mechanics
by highlighting the flexibility of the cochlear partition
(CP), particularly the osseous spiral lamina (OSL) and
cochlear partition bridge (CPB). The roles of these
structures are poorly understood, because experimental data
on CP motion remain sparse and spatially limited and most
inner ear models consider the OSL and CPB rigid. This thesis
advances our understanding of the vibroacoustic mechanisms
in AC and BC hearing by systematically separating the
auditory system into subsystems. First, the structural
motion of the EC is analysed, with particular emphasis on
how the motions of the EC entrance and tympanic membrane
interact with the vibrations of the EC wall in generating
the EC sound pressure underlying the OE. An impedance
boundary condition is introduced to account for these
contributions in OE models. Circuit calculations, based on
an EC motion extracted from a finite element model of a
human head, reveal that the motions of the EC entrance and
tympanic membrane affect the EC sound pressure at low
frequencies, especially under occluded conditions. This
finding may help reconcile discrepancies between OE
simulations and experimental data. Second, an anatomical
finite element model of the human inner ear is introduced,
allowing the OSL and CPB to be modeled as either rigid or
flexible structures. When applying stimulation at the oval
window – representing AC and BC transmission via this
pathway – the simulations reveal that the OSL
significantly influences cochlear impedances, CP stiffness,
and overall CP motion. Furthermore, when incorporating the
rigid body motion of the inner ear during BC, the
simulations identify a compressional motion of the OSL that
increases the differential volume velocity at the round
window compared the oval window, offering an alternative
explanation for experimental observations previously
attributed to "third-window" effects in BC hearing. These
findings highlight the importance of considering the
flexibility of the OSL and CPB when interpreting
experimental data, challenging classical concepts of inner
ear function that assume a rigid OSL and neglect the CPB.
Overall, the results suggest that the OSL plays a more
important role in both AC and BC hearing than previously
recognized. While this work advances our understanding of
hearing by focusing separately on different auditory
subsystems, future work should integrate these insights into
comprehensive models, such as full-head finite element
simulations, to further elucidate the interactions between
the AC and BC pathways and their relative importance.
Ultimately, these findings will contribute to improvements
in hearing technologies, including hearing devices, hearing
protection, and BC hearing aids.},
cin = {613510},
ddc = {621.3},
cid = {$I:(DE-82)613510_20140620$},
pnm = {SFB 1330 A04 - Charakterisierung der Abweichung zwischen
Akustik und ihrer Wahrnehmung (A04) (406028354) / SFB 1330:
Hörakustik: Perzeptive Prinzipien, Algorithmen und
Anwendungen},
pid = {G:(GEPRIS)406028354 / G:(GEPRIS)352015383},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
doi = {10.18154/RWTH-2025-07039},
url = {https://publications.rwth-aachen.de/record/1016952},
}
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