Dual-electrode pitch discrimination with sequential interleaved stimulation by cochlear implant users

Kwon, Bom Jun; Honert, Chris van den

doi:10.1121/1.2208152

Cited by 43 publications

(48 citation statements)

References 10 publications

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“…Electrode-electrode interactions have also been observed in cochlear implant (CI) patients. In psychophysical tests conducted on these patients, it was found that stimulus schemes that allowed for only interleaved pulsing between adjacent electrodes resulted in improved scores in the closed-set identification of consonants and the open-set recognition of words and sentences when compared with schemes incorporating simultaneous pulsing between adjacent electrodes [49], [50]. These interactions then should be ignored when making assumptions about the overall field profile at the multielectrode array-retina interface.…”

Section: Discussionmentioning

confidence: 99%

AnIn VitroModel of a Retinal Prosthesis

Ahuja

Behrend

Kuroda

et al. 2008

IEEE Trans. Biomed. Eng.

104

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Epiretinal prostheses are being developed to bypass a degenerated photoreceptor layer and excite surviving ganglion and inner retinal cells. We used custom microfabricated multielectrode arrays with 200-μm-diameter stimulating electrodes and 10-μm-diameter recording electrodes to stimulate and record neural responses in isolated tiger salamander retina. Pharmacological agents were used to isolate direct excitation of ganglion cells from excitation of other inner retinal cells. Strength-duration data suggest that, if amplitude will be used for the coding of brightness or gray level in retinal prostheses, shorter pulses (200 μs) will allow for a smaller region in the area of the electrode to be excited over a larger dynamic range compared with longer pulses (1 ms). Both electrophysiological results and electrostatic finite-element modeling show that electrodeelectrode interactions can lead to increased thresholds for sites half way between simultaneously stimulated electrodes (29.4 ± 6.6 nC) compared with monopolar stimulation (13.3 ± 1.7 nC, p < 0.02). Presynaptic stimulation of the same gan-glion cell with both 200-and 10-μm-diameter electrodes yielded threshold charge densities of 12 ± 6 and 7.66 1.30 nC/cm 2 , respectively, while the required charge was 12.5 ± 6.2 and 19 ± 3.3 nC.

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Section: Discussionmentioning

confidence: 99%

AnIn VitroModel of a Retinal Prosthesis

Ahuja

Behrend

Kuroda

et al. 2008

IEEE Trans. Biomed. Eng.

104

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“…McDermott and McKay (1994) among others (e.g., Kwon and van den Honert, 2006;Nobbe et al, 2007) have shown that intermediate pitches are produced when closely-spaced electrodes are stimulated in a rapid sequence, as compared to the pitches that are produced when each of the electrodes is stimulated separately. The pitch elicited with the rapid sequential stimulation varies according to the ratio of the currents delivered to the two electrodes.…”

Section: Possible Deficit In the Representation Of Fine Structure Infmentioning

confidence: 99%

Cochlear implants: A remarkable past and a brilliant future

2008

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The aims of this paper are to (i) provide a brief history of cochlear implants; (ii) present a status report on the current state of implant engineering and the levels of speech understanding enabled by that engineering; (iii) describe limitations of current signal processing strategies and (iv) suggest new directions for research. With current technology the "average" implant patient, when listening to predictable conversations in quiet, is able to communicate with relative ease. However, in an environment typical of a workplace the average patient has a great deal of difficulty. Patients who are "above average" in terms of speech understanding, can achieve 100% correct scores on the most difficult tests of speech understanding in quiet but also have significant difficulty when signals are presented in noise. The major factors in these outcomes appear to be (i) a loss of low-frequency, fine structure information possibly due to the envelope extraction algorithms common to cochlear implant signal processing; (ii) a limitation in the number of effective channels of stimulation due to overlap in electric fields from electrodes, and (iii) central processing deficits, especially for patients with poor speech understanding. Two recent developments, bilateral implants and combined electric and acoustic stimulation, have promise to remediate some of the difficulties experienced by patients in noise and to reinstate low-frequency fine structure information. If other possibilities are realized, e.g., electrodes that emit drugs to inhibit cell death following trauma and to induce the growth of neurites toward electrodes, then the future is very bright indeed.

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“…For example, the new strategy uses a high-resolution FFT-based frequency decomposition which results in small filter overlaps across channels. Such high-resolution analysis is important to minimize "incidental" across-channel "pitch steering" associated with non-simultaneous stimulation which occurs in CIS-like strategies (Kwon and van den Honert, 2006b;McDermott and McKay, 1994). In contrast, the baseline strategy has filter bands with greater overlaps.…”

Section: Evidence Of Current Steering In Human Subjectsmentioning

confidence: 99%

Current focusing and steering: Modeling, physiology, and psychophysics

Bonham

Litvak²

2008

Hearing Research

165

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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Dual-electrode pitch discrimination with sequential interleaved stimulation by cochlear implant users

Cited by 43 publications

References 10 publications

AnIn VitroModel of a Retinal Prosthesis

AnIn VitroModel of a Retinal Prosthesis

Cochlear implants: A remarkable past and a brilliant future

Current focusing and steering: Modeling, physiology, and psychophysics

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