Different bone conduction hearing aids (BCHA) are commercially available. They are attached to the head in different ways. The aim of this work is an experimental evaluation of the performance of a new transcutaneous (surface mounted via adhesive pad) actuator of a BCHA.
Experiments were conducted on a Thiel embalmed whole head cadaver specimen. The electromagnetic actuators from a commercial BCHA (Adhear) was used to provide stepped sine stimulus in the range of 0.1-10 kHz. The BCHA was coupled to a skin surface adhesion that was placed on the mastoid. The response was monitored as motions of the ipsi- and contralateral promontory, and as motions of the ipsi-, top and contra-lateral skull surface. Promontory motion was quantified via a three-dimensional laser Doppler vibrometer (3D LDV) system. Analogously, surface motion was registered by sequentially measuring ~200 points on the skull surface (~ 15-20 mm pitch) via 3D LDV. The data were compared to corresponding measurements obtained with a Baha Power that was coupled to skin on the Mastoid via a 5 Newton steelband.
Ipsilateral and contralateral promontory vibration for stimulation with the Adhear are comparable to stimulation with the Baha Power on the 5 Newton steelband with regard to frequency dependent amplitude and phase, as well as the contribution of the motion components. The surface motion of the skull experiences a similar complex motion for both stimulation modes.
Although the Adhear is coupled without any pressure to the skin over the mastoid whereas the Baha power is attached with a 5 Newton steelband, the vibration parameters investigated are comparable.
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