A Novel Measurement Approach for Inductive Through-the-Head Coupling

Worldwide, one in three adults aged 65 and above suffers from a form of hearing loss often affecting both ears. As a compensation, assistive listening devices are applied. Recent research shows, that networking two devices improves the speech understanding significantly. However, establishing a wireless low-power link through-the-head is challenging due to an extremely loose coil coupling (ratio of spacing to coil diameter > 50). Within the talk, a novel strategy is presented to determine the mutual inductance in the range of 10-1 H and below for such a coil arrangement. This level of sensitivity is required for through-the-head evaluations and exceeds the performance of standard approaches (they work for ratios of coil spacing to coil diameter < 5). The concept is verified by measurements and simulations which show a great degree of accordance. Transfer of the methodology into other applications is possible.