Cochlear implants (CIs) provide excellent functional hearing to most deaf individuals, but the benefits are limited when listening in noise or to complex sounds like music. To improve cochlear implant performance we need to identify the most important cues for these difficult listening situations and find ways to present these cues through the implant. Improving spectral selectivity should improve implant performance but is limited by physical, biological and perceptual factors. For an individual implant listener, spectra selectivity may be limited by poor electrode placement and/or poor nerve survival. New techniques (current focusing) have been investigated to reduce current spread and therefore improve spectral selectivity. However, data from our lab suggest that current focusing only reduces spread of excitation (SOE) in about half of the patients tested. Performance improvements from current focusing can only be expected when the SOE is actually reduced. In the proposed experiments, we will provide the first within-subject's measurements of changes in speech in noise and music tasks (Specific Aim 3) as they relate to changes in multi-channel spectral pattern discrimination (Specific Aim 2) and reduction in single-channel SOE (Specific Aim 1). We expect to find that current focusing can result in reductions in SOE, which in turn will produce improvements in speech in noise and music performance. However, because of local neural survival, electrode placement, and variable local impedances, we expect to find that a reduction in SOE will only be achievable in a subset of patients. Therefore, we will also investigate quick (and clinically relevant) methods of predicting which patients will benefit from current focusing (experiments 2 and 3). The overall goals of this research are to determine if functional spectral resolution can be improved via current focusing for some patients and to determine in a clinically relevant procedure which patients would benefit from current focusing. We hypothesize that if current focusing can reduce the spread of excitation, then spectral resolution will be increased and improve CI performance in challenging listening conditions (e.g., speech in noise, music). The proposed research is significant because it aims to: a) evaluate the relationship between changes in SOE, multi-channel discrimination, and performance in speech and music tasks, b) improve performance for CI listeners. The research is innovative as the first study to investigate within subjects the effect of single-channel SOE on multi-channel spectral and speech processor performance by directly manipulating the degree of current spread. The research approach combines objective measures (ECAPs), subjective descriptors, single- and multi-channel psychophysics, and evaluations of experimental signal processing to better understand who might benefit from current focusing, and under what circumstances.
Cochlear implant (CI) users have difficulty in challenging listening conditions (e.g. speech in noise and music perception) presumably because of channel interactions from each electrode. We will investigate if current-focusing will reduce the spread of excitation, increase multi-channel spectral resolution, and provide better performance in difficult listening conditions. Furthermore, we will investigate quick (i.e. clinically-relevant) methods of determining which patients would benefit from restricting the spread of excitation.
|Landsberger, David M; Vermeire, Katrien; Claes, Annes et al. (2016) Qualities of Single Electrode Stimulation as a Function of Rate and Place of Stimulation with a Cochlear Implant. Ear Hear 37:e149-59|
|Aronoff, Justin M; Stelmach, Julia; Padilla, Monica et al. (2016) Interleaved Processors Improve Cochlear Implant Patients' Spectral Resolution. Ear Hear 37:e85-90|
|Preston, Jonathan L; Maas, Edwin; Whittle, Jessica et al. (2016) Limited acquisition and generalisation of rhotics with ultrasound visual feedback in childhood apraxia. Clin Linguist Phon 30:363-81|
|Padilla, Monica; Landsberger, David M (2016) Reduction in spread of excitation from current focusing at multiple cochlear locations in cochlear implant users. Hear Res 333:98-107|
|Aronoff, Justin M; Padilla, Monica; Fu, Qian-Jie et al. (2015) Contralateral masking in bilateral cochlear implant patients: a model of medial olivocochlear function loss. PLoS One 10:e0121591|
|Landsberger, David M; Svrakic, Maja; Roland Jr, J Thomas et al. (2015) The Relationship Between Insertion Angles, Default Frequency Allocations, and Spiral Ganglion Place Pitch in Cochlear Implants. Ear Hear 36:e207-13|
|Vermeire, Katrien; Landsberger, David M; Van de Heyning, Paul H et al. (2015) Frequency-place map for electrical stimulation in cochlear implants: Change over time. Hear Res 326:8-14|
|Preston, Jonathan L; McCabe, Patricia; Rivera-Campos, Ahmed et al. (2014) Ultrasound visual feedback treatment and practice variability for residual speech sound errors. J Speech Lang Hear Res 57:2102-15|
|Landsberger, David M; Mertens, Griet; Punte, Andrea Kleine et al. (2014) Perceptual changes in place of stimulation with long cochlear implant electrode arrays. J Acoust Soc Am 135:EL75-81|
|Padilla, Monica; Landsberger, David M (2014) Loudness summation using focused and unfocused electrical stimulation. J Acoust Soc Am 135:EL102-8|
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