Electrical field imaging as a means to predict the loudness of monopolar and tripolar stimuli in cochlear implant patients.

Tripolar and other electrode configurations that use simultaneous stimulation inside the cochlea have been tested to reduce channel interactions compared to the monopolar stimulation conventionally used in cochlear implant systems. However, these "focused" configurations require increased current levels to achieve sufficient loudness. In this study, we investigate whether highly accurate recordings of the intracochlear electrical field set up by monopolar and tripolar configurations correlate to their effect on loudness.

Current steering and current focusing in cochlear implants: comparison of monopolar, tripolar, and virtual channel electrode configurations.

Objectives: To compare the effects of Monopole (Mono), Tripole (Tri), and "Virtual channel" (Vchan) electrode configurations on spectral resolution and speech perception in a crossover design.

Design: Nine experienced adults who received an Advanced Bionics CII/90K cochlear implant participated in a crossover design using three experimental strategies for 2 wk each. Three strategies were compared: (1) Mono; (2) Tri with current partly returning to adjacent electrodes and partly (25 or 75%) to the extracochlear reference; and (3) a monopolar "Vchan" strategy creating seven intermediate channels between two contacts.

Speech perception with mono- and quadrupolar electrode configurations: a crossover study.

Objective: To study the effect of two multipolar electrode configurations on speech perception, pitch perception, and the intracochlear electrical field.

Study Design: Crossover design; within subject.

Setting: Tertiary referral center.