title: Reduction in spread of excitation from current focusing at multiple cochlear locations in cochlear implant users.
abstract: Channel interaction from a broad spread of excitation is likely to be a limiting factor in performance by cochlear implant users. Although partial tripolar stimulation has been shown to reduce spread of excitation, the magnitude of the reduction is highly variable across subjects. Because the reduction in spread of excitation is typically only measured at one electrode for a given subject, the degree of variability across cochlear locations is unknown. The first goal of the present study was to determine if the reduction in spread of excitation observed from partial tripolar current focusing systematically varies across the cochlea. The second goal was to measure the variability in reduction of spread of excitation relative to monopolar stimulation across the cochlea. The third goal was to expand upon previous results that suggest that scaling of verbal descriptors can be used to predict the reduction in spread of excitation, by increasing the limited number of sites previously evaluated and verify the relationships remain with the larger dataset. The spread of excitation for monopolar and partial tripolar stimulation was measured at 5 cochlear locations using a psychophysical forward masking task. Results of the present study suggest that although partial tripolar stimulation typically reduces spread of excitation, the degree of reduction in spread of excitation was found to be highly variable and no effect of cochlear location was found. Additionally, subjective scaling of certain verbal descriptors (Clean/Dirty, Pure/Noisy) correlated with the reduction in spread of excitation suggesting sound quality scaling might be used as a quick clinical estimate of channels providing a reduction in spread of excitation. This quick scaling technique might help clinicians determine which patients would be most likely to benefit from a focused strategy.
authors.affiliation: House Research Institute, Department of Communication and Neuroscience, 2100 West 3rd Street, Los Angeles, CA 90057, USA; Department of Otolaryngology, New York University School of Medicine, 550 1st Avenue STE NBV 5E5, New York, NY 10016, USA; Department of Otolaryngology, Keck School of Medicine, University of Southern California, 806 W. Adams Blvd., Los Angeles, CA 90007, USA. Electronic address: Monica.PadillaVelez@nyumc.org.
authors.forename: Monica
authors.initials: M
authors.lastname: Padilla
authors.affiliation: House Research Institute, Department of Communication and Neuroscience, 2100 West 3rd Street, Los Angeles, CA 90057, USA; Department of Otolaryngology, New York University School of Medicine, 550 1st Avenue STE NBV 5E5, New York, NY 10016, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: Landsberger
mesh_terms: D000161:Acoustic Stimulation; D000368:Aged; D000369:Aged, 80 and over; D001307:Auditory Perception; D003051:Cochlea / Q000503:physiopathology*; D019929:Cochlear Implantation / Q000295:instrumentation*; D003054:Cochlear Implants; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D008144:Loudness Perception; D008297:Male; D008875:Middle Aged; D009622:Noise / Q000009:adverse effects; D010470:Perceptual Masking; D019986:Persons with Hearing Disabilities / Q000523:psychology / Q000534:rehabilitation*; D011571:Psychoacoustics; D012815:Signal Processing, Computer-Assisted
keywords: Cochlear; Implants; Scaling; Spread; Tripolar