Compatibility of a Magnetic Position Tracker with a Cochlear Implant System

Objectives: The aim of this study was to reveal possible interspersion of a magnetic position tracking device into a cochlear implant system, which could lead to harmful signals on the implanted electrode. Design: Signals at the output of the speech processor's compression stage and at the implant's electrode were recorded and analyzed for unwanted distortion or corrupted pulses related to the presence of the magnetic tracking device. Results: No systematic impact of a Polhemus Liberty Latus magnetic tracking system on the output signals of an Advanced Bionics HiRes90k cochlear implant and Platinum Series speech processor was found. Conclusions: The results suggest no objections for using the Polhemus Liberty Latus magnetic position tracker with the Advanced Bionics Platinum series speech processor and HiRes90k cochlear implant in research, for example, on spatial hearing. This result is likely transferable to other cochlear implants because (i) all manufacturers adhere to equally high electromagnetic interference standards and (ii) electromagnetic signals used by the transmission links of current cochlear implants and trackers differ in frequency by roughly 2 decades, making interference unlikely.