Direct Drive Bone Conduction Stimulation: Experimental Studies on Functionality and Transmission with Focus on the Bone Conduction Implant
Licentiatavhandling, 2017

Sound is conducted to the inner ear in two ways: by air and by bone. Air conduction (AC) hearing consists of sound waves entering the ear canal and reaching the cochlea, the main hearing organ, via the middle ear. In bone conduction (BC) hearing, instead, the transmission is through soft tissues and bone. These two pathways coexist and complement each other, although in normal hearing subjects the AC part is prevalent over the BC part in most of the ordinary hearing situations. BC hearing can represent an effective way to rehabilitate hearing impaired patients who would not benet from conventional AC hearing aids. This is the case when the hearing impairment is located in the outer or middle ear, or if the patients have chronic infections or malformations preventing them from wearing earmolds. The key idea in bone conduction devices (BCDs) is to generate vibrations with a transducer and transmit them via the skull bone to the inner ear. At present, the most common BCD is probably the bone anchored hearing aid (BAHA), consisting of a single-unit device attached to a skin penetrating screw in the parietal bone. To overcome the issues related to the skin penetration, the development of BCDs is recently focusing on so-called active transcutaneous devices, whose main feature is to have the bone transducer implanted under intact skin. In this thesis, the novel active transcutaneous bone conduction implant (BCI), currently in advanced clinical trial phase, was compared to BAHAs in terms of audiological tests and perceived rehabilitation effect. The outcomes showed that the BCI can be a valid alternative to BAHAs for indicated patients. Preliminary investigations were also performed on how the transmission of vibrations is affected by different ways of attaching the transducer to the skull bone. It was found that the relation varies substantially with frequency, with a general trend of improved transmission when the contact area between transducer and bone is limited. Finally, a new verication method of the implant functionality was evaluated intra- and post- operatively. The method, consisting in the measurement of the sound pressure in the nostril, seems promising and the implant to bone transmission was found stable over time.


audiological tests

Bone Anchored Hearing Aids

Bone Conduction

comparative study

Bone Conduction Implant


room EC, Hörsalsvägen 11
Opponent: Prof. Stefan Stenfelt, Department of Clinical and Experimental Medicine, Linköping University, Sweden.


Cristina Rigato

Signaler och system, Signalbehandling och medicinsk teknik, Medicinska signaler och system

“Direct Bone Conduction Stimulation: Ipsilateral Effect of Different Transducer Attachments in Active Transcutaneous Devices”, Cristina Rigato, Sabine Reinfeldt, Bo Håkansson, Karl-Johan Fredén Jansson, Erik Renvall, and Måns Eeg-Olofsson. Submitted to Hearing Research, 2017.

“Nasal Sound Pressure as Objective Verification of Implant in Active Transcutaneous Bone Conduction Devices”, Sabine Reinfeldt, Cristina Rigato, Bo Håkansson, Karl- Johan Fredén Jansson, and Måns Eeg-Olofsson. Manuscript, 2017.


Annan hälsovetenskap




Innovation och entreprenörskap


Livsvetenskaper och teknik


Chalmers tekniska högskola

room EC, Hörsalsvägen 11

Opponent: Prof. Stefan Stenfelt, Department of Clinical and Experimental Medicine, Linköping University, Sweden.