Numerical analysis of the effects of ossicular chain malformations on bone conduction stimulation

Abstract

To assess the effects of ossicular chain malformations on the performance of bone conduction hearing aids, a human ear finite-element model that includes an ear canal, a middle ear, and a spiral cochlea incorporating the third windows was established. This finite element model was built based on micro-computed tomography scanning and reverse modelling techniques, and the reliability of the finite element model was verified by comparison with reported experimental data. Based on this model, two main types of ossicular chain malformations, i.e., the incudostapedial disconnection and the ossicles fixation, were simulated, and their influences on bone conduction were analyzed by comparing the trans-cochlear-partition differential pressures. The results indicate that the incudostapedial disconnection mainly deteriorates the bone conduction response at mid frequencies. The stapes fixation has the largest effect among the ossicles fixation with the bone conduction stimulation, which also mainly decreases the mid-frequency response of the bone conduction, especially at 2 kHz. As the speech intelligibility has the most important frequency range at the range between 1 kHz and 2.5 kHz, the mid-frequency deterioration caused by ossicular chain malformations should be compensated in optimizing the design of the bone conduction hearing aids. For treating patients with the ossicular chain malformations, especially for the patients who suffer from the stapes fixation, the output of bone conduction hearing aids’ actuator in the middle frequency band should be improved.

Keywords:

• Bone conduction hearing aids
• ossicular chain malformations
• finite element model
• incudostapedial disconnection
• ossicles fixation

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by National Natural Science Foundation of China (grant no. 51775547), the Shanghai Science and Technology Committee Fund (grant no. 17411962200), Top-notch Academic Program Development of Jiangsu Higher Education Institutions, and the Priority Academic Program Development of Jiangsu Higher Education Institutions.