Effect of stimulation parameters on sequential current-steered stimuli in cochlear implants

Abstract

Manipulation of cochlear implant (CI) place pitch was carried out with current steering by stimulating two CI electrodes sequentially. The objective was to investigate whether shifts in activated neural populations could be achieved to produce salient pitch differences and to determine which stimulation parameters would be more effective in steering of current. These were the pulse rate and pulse width of electrical stimuli and the distance between the two current-steering electrodes. Nine CI users participated, and ten ears were tested. The pattern of pitch changes was not consistent across listeners, but the data suggest that individualized selection of stimulation parameters may be used to effect place pitch changes with sequential current steering. Individual analyses showed that pulse width generally had little influence on the effectiveness of current steering with sequential stimuli, while more salient place pitch shifts were often achieved at wider electrode spacing or when the stimulation pulse rate was the same as that indicated on the clinical MAP (the set of stimulation parameters) of the listener. Results imply that current steering may be used in CIs that allow only sequential stimulation to achieve place pitch manipulation.

A Tailored and Transdisciplinary Approach to Cochlear Implants

“…Despite different designs that attempt to address different issues, outcomes are similar across electrode designs and speech processors [3]. For example, current focusing and current steering methods are used to mitigate the effect of current spread [9,10], some electrode designs target deep insertions to ensure that the low-frequency region of the cochlea is stimulated [11] and electrode array positioning is either perimodiolar or against the cochlear lateral wall [12]. These different designs have not solved the problem of variable outcomes across CI users [13].…”