Modellering en preklinische metingen van beengeleidingshoren: inzichten in de conductie van geluid en de efficiëntie van implantaten.
Year: 2025
Type: dissertation
Abstract: Bone conduction devices (BCDs) are innovative hearing aids that deliver sound vibrations via bone conduction through the skull, bypassing the outer and middle ear to directly stimulate the cochlea. This technology is particularly suited for patients with conductive hearing loss, who have a dysfunctional outer and/or middle ear. Beyond clinical applications, bone conduction technology has also guided the development of consumer products, notably bone conduction headphones. These headphones allow the user to maintain environmental awareness, to listen underwater, and to combine them with hearing protection. While BCDs enable many individuals with hearing loss to hear more effectively, they still have notable limitations. The primary constraint is their maximum output force level, which directly impacts the sound intensity delivered to the inner ear. This limitation restricts the degree of hearing loss that BCDs can effectively address and influences critical aspects of auditory perception, including speech recognition, spatial awareness, and overall sound quality. To improve patients' hearing outcomes with BCDs, two main strategies are possible: increasing the maximum output force level or enhancing the efficiency of sound transfer from the device to the inner ear. This thesis focuses on the latter approach. However, to improve the sound transfer from the device, a better understanding of the mechanisms underlying sound transmission through bone and the subsequent interaction with the cochlea, is required. To address this knowledge gap, this research employs two methods: preclinical measures in human cadaveric specimens and lumped element modelling. Preclinical measures are used to directly observe sound propagation from the BCD to the cochlea in human cadaveric specimens. The key measures are ear canal pressure, promontory velocity, and intracochlear pressures, providing a detailed look at how sound energy travels from the BCD to the cochlea. Since it is hypothesised that the stimulation position has an effect on the sound transfer, experiments are conducted with bone conduction stimulation at multiple anatomical sites. The first study examines sound propagation when the device is placed at more distal points on the skull surface, using a Cochlear Baha hearing aid, while the second study investigates stimulation closer to the cochlea within the surgical opening of the mastoidectomy and tympanotomy. By systematically evaluating the amplitude of the objective measures, the research identifies the most effective stimulation points. In addition to these experimental studies, lumped element modelling is utilized to develop a simplified but effective representation of the mechanical system involved in sound transfer. A lumped element model identifies the key masses and interconnections within the system, offering a comprehensive framework for analysing sound propagation from the BCD to the cochlea. First, a systematic review of existing lumped element models evaluates their accuracy in predicting sound transfer and identifies limitations that may be addressed in future models. Thereafter, the findings from the preclinical experiments are integrated into a revised LEM, refining the model based on empirical data. This updated model offers a more accurate and robust representation of the sound transfer process, including the function of the temporal bone and cochlear fluid, as well as the osseous and non-osseous pathways. By combining experimental data with theoretical modelling, this research contributes to a deeper understanding of the transfer of sound energy in bone conduction. The results provide insights into the underlying mechanisms of sound propagation through bone conduction and identify potential optimal stimulation positions that enhance the effectiveness of bone conduction technologies. The fin[1]dings have the potential to improve the performance of both medical devices for individuals with hearing loss and consumer products like bone conduction headphones, ultimately advancing sound quality, energy efficiency, and user comfort in a range of applications.
Source: Lirias
Author: Wils, Irina
Language: English
Topic: Ear Surgery and Otitis Media
Subfield: Otorhinolaryngology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7113007571
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