Description

During the last years hearing aid technology has improved strongly and has made great progress in miniaturization. More and more implantable hearing systems are available to treat different kinds of hearing loss

A new generation of hearing aids are active middle ear implants (AMEI). They normally consist of a sound converter, which picks up the incoming sound and translates it into electrical signals, and of a implanted electromechanical actuator, which directly or indirectly stimulates the inner ear.

The actual research project is related to the experimental investigation and the computational simulation of the mechanical behaviour of AMEI. It is carried out together with industrial partners (Phonak Acoustic Implants, Switzerland). The project objective is the optimal mechanical design of AMEI in terms of stimulating the sense of hearing.

In laboratory experiments the spatial motion behaviour of AMEI can be measured by means of 3D Laser Doppler Vibrometry. A comparison with the motion patterns of the natural middle ear, which are available from measurements of the local research group Dynamics of Hearing and its clinical partners, allows an assessment of the inner ear stimulation. By using artefacts of natural structures, in-situ measurements of AMEI under defined boundary conditions are possible.

The computational simulation of the spatial motions and the transfer behaviour of AMEI allows a prediction of the dynamical behaviour under different working conditions as well as a sensitivity analysis, e.g. on the variation of geometry parameters, already during the development phase. In virtual experiments the behaviour of AMEI under variable boundary conditions can be investigated, e.g. the influence of nonlinear coupling between AMEI and driven natural structures on the dynamical behaviour or the variation of the working point due to a static preload. The visualization of the simulated motions is done in a virtual reality environment.

The basis for the simulation of AMEI and the coupled natural structures is the three dimensional mechanical modelling, based on the concept of elastic multi-body systems (EMBS). For the computational implementation there is the program system Neweul-M² avilable, which was developed at the ITM. The model's physical parameters are gained from laboratory experiments and simulative investigations of subsystems. By means of a parameter optimization the simulated transfer behaviour can be fit to the measured behaviour of the real system.

Contact

• Dr.-Ing. Albrecht Eiber
• Dipl.-Ing. Christoph Heckeler