A uniform graphical representation of intensity coding in current-generation cochlear implant systems

Abstract

Objectives: Understanding and predicting the impact of MAP changes on the electrical current delivered at the level of cochlear implant (CI) electrodes is challenging. However, it is an important prerequisite for effectively programming these devices in clinical practice. This article describes a graphical representation to illustrate the intensity-coding behavior of four CI systems (Cochlear, MED-EL, Advanced Bionics, and Neurelec).

Design: For this the authors have broken down the intensity coding into two separate transformations: (1) from broadband acoustical input to band limited channel amplitude and (2) the mapping function within a single channel. These functions have been synthesized and presented in a uniform plot across brands.

Results: The plot describes the output of a CI channel in response to different input signals. This has been incorporated in an interactive software application that illustrates the different stages of intensity coding and the impact of the relevant fitting parameters for each CI brand.

Conclusions: The plot provides the clinician with an assistive tool to better understand and predict the behavior of CIs, which may lead to more knowledgeable interpretation and CI programming.