Current Steering Creates Additional Pitch Percepts in Adult Cochlear Implant Recipients

Firszt, Jill B.; Koch, Dawn Burton; Downing, Mark; Litvak, Leonid M.

doi:10.1097/01.mao.0000281803.36574.bc

Cited by 125 publications

(93 citation statements)

References 9 publications

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“…Due to broad spread of currents through the scala tympani, it is possible to use electrodes separated by a distance of as much as 16 mm to evoke such intermediate pitches . The resolution, identified as the number of intermediate pitches, achievable with simultaneous stimulation has been quantified in several studies (Donaldson et al, 2005;Firszt et al, 2007;Koch et al, 2007). Generally, it is found that on average 4-7 intermediate pitch sensations per pair of adjacent electrodes (spaced between 0.85 and 1.1 mm, depending on electrode type) could be perceived using current steering, with a trend for basal pairs to produce fewer intermediate pitches.…”

Section: Evidence Of Current Steering In Human Subjectsmentioning

confidence: 99%

Current focusing and steering: Modeling, physiology, and psychophysics

Bonham

Litvak²

2008

Hearing Research

163

138

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Current steering and current focusing are stimulation techniques designed to increase the number of distinct perceptual channels available to cochlear implant (CI) users by adjusting currents applied simultaneously to multiple CI electrodes. Previous studies exploring current steering and current focusing stimulation strategies are reviewed, including results of research using computational models, animal neurophysiology, and human psychophysics. Preliminary results of additional neurophysiological and human psychophysical studies are presented that demonstrate the success of current steering strategies in stimulating auditory nerve regions lying between physical CI electrodes, as well as current focusing strategies that excite regions narrower than those stimulated using monopolar configurations. These results are interpreted in the context of perception and speech reception by CI users. Disparities between results of physiological and psychophysical studies are discussed. The differences in stimulation used for physiological and psychophysical studies are hypothesized to contribute to these disparities. Finally, application of current steering and focusing strategies to other types of auditory prostheses is also discussed.

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Section: Evidence Of Current Steering In Human Subjectsmentioning

confidence: 99%

Current focusing and steering: Modeling, physiology, and psychophysics

Bonham

Litvak²

2008

Hearing Research

163

138

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“…This will affect or distort the intended perception and usually is undesirable. However, experiments show that by exciting two adjacent electrodes simultaneously in a suitable manner, 2,9,10,15,17,[22][23][24] the CI users can perceive a pitch which is between two pitches perceived when the two electrodes are excited individually. The intermediate pitch is the so called virtual channel since there is no real electrode to generate a real stimulation channel there.…”

Section: Introductionmentioning

confidence: 99%

“…The intermediate pitch is the so called virtual channel since there is no real electrode to generate a real stimulation channel there. The mechanism for controlling the virtual channels, called current steering, 2,10,15,23 steers the current applied to adjacent electrodes in order to generate virtual channels according to the current ratio between the electrodes. This technique can be used to expand the spectral resolution without changing the implanted hardware or the number of CI electrodes.…”

Section: Introductionmentioning

confidence: 99%

“…In clinical experiments, however, virtual channels are not always perceived, 2,10,15,[22][23][24] perhaps due to the individual hearing loss factor of each user or improper electrical stimulation from the electrodes. From the experiment results, it is found that virtual channels at the medial and apical electrode pairs are easier to perceive.…”

Section: Introductionmentioning

confidence: 99%

“…From the experiment results, it is found that virtual channels at the medial and apical electrode pairs are easier to perceive. 10,15 Since the medial and apical electrodes are usually closer to the lateral wall of the cochlea, thus generating a larger current spread and more channel interaction. 21 Clinical experiments show the possibility that the generation of virtual channels by electrical stimulation could be linked to the distance between the electrode contacts and the auditory nerves (modiolus).…”

Section: Introductionmentioning

confidence: 99%

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Conditions for Generating Virtual Channels in Cochlear Prosthesis Systems

Choi

Hsu

2008

Ann Biomed Eng

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Abstract-Simultaneous electrical stimulation of neighboring electrodes in cochlear prosthesis systems generates channel interaction. However, intermediate channels, or virtual channels between the neighboring electrodes can be created through controlled channel interaction. This effect may be exploited for sending new information to the hearing nerves by stimulating in a suitable manner. The actual stimulation sites are therefore not limited to the number of electrodes. Clinical experiments, however, show that virtual channels are not always perceived. In this paper, electrical simulation with finite element analysis on a half turn human cochlea model is adopted to model the virtual channel effect, and the conditions for generating virtual channels are discussed. Five input current ratios (100/0, 70/30, 50/50, 30/70, 0/100) are applied to generate virtual channels. Three electrode arrays parameters are taken into consideration: distance between electrode contact and modiolus, spacing between adjacent electrode contacts and scale of electrode contact size. By observing the activating function contours, the virtual channel patterns and performances can be measured and examined. The results showed that a broad excitation pattern is necessary to produce the kind of electrode interaction that can form distinct virtual channels.

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