The Mechanical Impedance of the Human Skull via Direct Bone Conduction Implants

Bo Håkansson,1 Fausto Woelflin,1,2 Anders Tjellström,3 William Hodgetts2 1Department of Electrical Engineering, Chalmers University of Technology, Gothenburg, Sweden; 2Department of Communication Sciences and Disorders, University of Alberta, Edmonton, Canada; 3Department of Otola...

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Autores principales:	Håkansson B, Woelflin F, Tjellström A, Hodgetts W
Formato:	article
Lenguaje:	EN
Publicado:	Dove Medical Press 2020
Materias:	bone conduction mechanical impedance percutaneous hearing implants bone anchored hearing aid Medical technology R855-855.5
Acceso en línea:	https://doaj.org/article/9d65ef00e5264a8ea6f08c155a8d246b
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spelling	oai:doaj.org-article:9d65ef00e5264a8ea6f08c155a8d246b2021-12-02T12:23:45ZThe Mechanical Impedance of the Human Skull via Direct Bone Conduction Implants1179-1470https://doaj.org/article/9d65ef00e5264a8ea6f08c155a8d246b2020-09-01T00:00:00Zhttps://www.dovepress.com/the-mechanical-impedance-of-the-human-skull-via-direct-bone-conduction-peer-reviewed-article-MDERhttps://doaj.org/toc/1179-1470Bo Håkansson,1 Fausto Woelflin,1,2 Anders Tjellström,3 William Hodgetts2 1Department of Electrical Engineering, Chalmers University of Technology, Gothenburg, Sweden; 2Department of Communication Sciences and Disorders, University of Alberta, Edmonton, Canada; 3Department of Otolaryngology, Head and Neck Surgery, Sahlgrenska Academy, Gothenburg, SwedenCorrespondence: Bo HåkanssonDepartment of Electrical Engineering, Chalmers University of Technology, Hörsalsvägen 9, Gothenburg 41296, SwedenTel +46 317721807Email boh@chalmers.sePurpose: The mechanical skull impedance is used in the design of direct bone drive hearing systems. This impedance is also important for the design of skull simulators used in manufacturing, service, and fitting procedures of such devices.Patients and Methods: The skull impedance was measured in 45 patients (25 female and 20 male) who were using percutaneous bone conduction implants (Ponto system or Baha system). Patients were recruited as a consecutive prospective case series and having an average age of 55.4 years (range 18– 80 years). Seven patients were treated in Gothenburg, Sweden, and 38 patients in Edmonton, Canada. An impedance head (B&K 8001), driven by an excitation transducer with emphasized low-frequency response, was used to measure the mechanical point impedance with a swept sine from 100 to 10k Hz.Results and Discussion: The skull impedance was found to have an anti-resonance of approximately 150 Hz, with a median maximum magnitude of 4500 mechanical ohms. Below this anti-resonance, the mechanical impedance was mainly mass-controlled corresponding to an effective skull mass of 2.5 kg at 100 Hz with substantial damping from neck and shoulder. Above the anti-resonance and up to 4 kHz, the impedance was stiffness-controlled, with a total compliance of approximately 450n m/N with a small amount of damping. At frequencies above 4 kHz, the skull impedance becomes gradually mass-controlled originating from the mass of the osseointegrated implant and adjacent bone. No significant differences related to gender or skull abnormalities were seen, just a slight dependence on age and major ear surgeries. The variability of the mechanical impedance among patients was not found to have any clinical importance.Conclusion: The mechanical skull impedance of percutaneous implants was found to confirm previous studies and can be used for optimizing the design and test procedures of direct bone drive hearing implants.Keywords: bone conduction, mechanical impedance, percutaneous hearing implants, bone anchored hearing aidHåkansson BWoelflin FTjellström AHodgetts WDove Medical Pressarticlebone conductionmechanical impedancepercutaneous hearing implantsbone anchored hearing aidMedical technologyR855-855.5ENMedical Devices: Evidence and Research, Vol Volume 13, Pp 293-313 (2020)
institution	DOAJ
collection	DOAJ
language	EN
topic	bone conduction mechanical impedance percutaneous hearing implants bone anchored hearing aid Medical technology R855-855.5
spellingShingle	bone conduction mechanical impedance percutaneous hearing implants bone anchored hearing aid Medical technology R855-855.5 Håkansson B Woelflin F Tjellström A Hodgetts W The Mechanical Impedance of the Human Skull via Direct Bone Conduction Implants
description	Bo Håkansson,1 Fausto Woelflin,1,2 Anders Tjellström,3 William Hodgetts2 1Department of Electrical Engineering, Chalmers University of Technology, Gothenburg, Sweden; 2Department of Communication Sciences and Disorders, University of Alberta, Edmonton, Canada; 3Department of Otolaryngology, Head and Neck Surgery, Sahlgrenska Academy, Gothenburg, SwedenCorrespondence: Bo HåkanssonDepartment of Electrical Engineering, Chalmers University of Technology, Hörsalsvägen 9, Gothenburg 41296, SwedenTel +46 317721807Email boh@chalmers.sePurpose: The mechanical skull impedance is used in the design of direct bone drive hearing systems. This impedance is also important for the design of skull simulators used in manufacturing, service, and fitting procedures of such devices.Patients and Methods: The skull impedance was measured in 45 patients (25 female and 20 male) who were using percutaneous bone conduction implants (Ponto system or Baha system). Patients were recruited as a consecutive prospective case series and having an average age of 55.4 years (range 18– 80 years). Seven patients were treated in Gothenburg, Sweden, and 38 patients in Edmonton, Canada. An impedance head (B&K 8001), driven by an excitation transducer with emphasized low-frequency response, was used to measure the mechanical point impedance with a swept sine from 100 to 10k Hz.Results and Discussion: The skull impedance was found to have an anti-resonance of approximately 150 Hz, with a median maximum magnitude of 4500 mechanical ohms. Below this anti-resonance, the mechanical impedance was mainly mass-controlled corresponding to an effective skull mass of 2.5 kg at 100 Hz with substantial damping from neck and shoulder. Above the anti-resonance and up to 4 kHz, the impedance was stiffness-controlled, with a total compliance of approximately 450n m/N with a small amount of damping. At frequencies above 4 kHz, the skull impedance becomes gradually mass-controlled originating from the mass of the osseointegrated implant and adjacent bone. No significant differences related to gender or skull abnormalities were seen, just a slight dependence on age and major ear surgeries. The variability of the mechanical impedance among patients was not found to have any clinical importance.Conclusion: The mechanical skull impedance of percutaneous implants was found to confirm previous studies and can be used for optimizing the design and test procedures of direct bone drive hearing implants.Keywords: bone conduction, mechanical impedance, percutaneous hearing implants, bone anchored hearing aid
format	article
author	Håkansson B Woelflin F Tjellström A Hodgetts W
author_facet	Håkansson B Woelflin F Tjellström A Hodgetts W
author_sort	Håkansson B
title	The Mechanical Impedance of the Human Skull via Direct Bone Conduction Implants
title_short	The Mechanical Impedance of the Human Skull via Direct Bone Conduction Implants
title_full	The Mechanical Impedance of the Human Skull via Direct Bone Conduction Implants
title_fullStr	The Mechanical Impedance of the Human Skull via Direct Bone Conduction Implants
title_full_unstemmed	The Mechanical Impedance of the Human Skull via Direct Bone Conduction Implants
title_sort	mechanical impedance of the human skull via direct bone conduction implants
publisher	Dove Medical Press
publishDate	2020
url	https://doaj.org/article/9d65ef00e5264a8ea6f08c155a8d246b
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The Mechanical Impedance of the Human Skull via Direct Bone Conduction Implants

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