Spread of excitation varies for different electrical pulse shapes and stimulation modes in cochlear implants

2012 ◽  
Vol 290 (1-2) ◽  
pp. 21-36 ◽  
Author(s):  
Jaime A. Undurraga ◽  
Robert P. Carlyon ◽  
Olivier Macherey ◽  
Jan Wouters ◽  
Astrid van Wieringen
Keyword(s):  
Cochlear Implants ◽  
Electrical Pulse ◽  
Spread Of Excitation

scholarly journals Pitch ranking, electrode discrimination, and physiological spread of excitation using current steering in cochlear implants

2014 ◽  
Vol 136 (6) ◽  
pp. 3159-3171 ◽  
Author(s):  
Jenny L. Goehring ◽  
Donna L. Neff ◽  
Jacquelyn L. Baudhuin ◽  
Michelle L. Hughes
Keyword(s):  
Cochlear Implants ◽  
Current Steering ◽  
Spread Of Excitation

scholarly journals Simulating the effect of spread of excitation in cochlear implants

2008 ◽  
Vol 241 (1-2) ◽  
pp. 73-79 ◽  
Author(s):  
Mohamed Bingabr ◽  
Blas Espinoza-Varas ◽  
Philipos C. Loizou
Keyword(s):  
Cochlear Implants ◽  
Spread Of Excitation

scholarly journals Effect of Stimulus Polarity on Physiological Spread of Excitation in Cochlear Implants

2017 ◽  
Vol 28 (09) ◽  
pp. 786-798 ◽  
Author(s):  
Emily R. Spitzer ◽  
Michelle L. Hughes
Keyword(s):  
Cochlear Implants ◽  
Repeated Measures ◽  
Spatial Separation ◽  
Compound Action Potential ◽  
Mean Amplitude ◽  
Repeated Measures Design ◽  
Electrode Location ◽  
Current Pulses ◽  
Spread Of Excitation ◽  
Within Subjects

AbstractContemporary cochlear implants (CIs) use cathodic-leading, symmetrical, biphasic current pulses, despite a growing body of evidence that suggests anodic-leading pulses may be more effective at stimulating the auditory system. However, since much of this research on humans has used pseudomonophasic pulses or biphasic pulses with unusually long interphase gaps, the effects of stimulus polarity are unclear for clinically relevant (i.e., symmetric biphasic) stimuli.The purpose of this study was to examine the effects of stimulus polarity on basic characteristics of physiological spread-of-excitation (SOE) measures obtained with the electrically evoked compound action potential (ECAP) in CI recipients using clinically relevant stimuli.Using a within-subjects (repeated measures) design, we examined the differences in mean amplitude, peak electrode location, area under the curve, and spatial separation between SOE curves obtained with anodic- and cathodic-leading symmetrical, biphasic pulses.Fifteen CI recipients (ages 13–77) participated in this study. All were users of Cochlear Ltd. devices.SOE functions were obtained using the standard forward-masking artifact reduction method. Probe electrodes were 5–18, and they were stimulated at an 8 (of 10) loudness rating (“loud”). Outcome measures (mean amplitude, peak electrode location, curve area, and spatial separation) for each polarity were compared within subjects.Anodic-leading current pulses produced ECAPs with larger average amplitudes, greater curve area, and less spatial separation between SOE patterns compared with that for cathodic-leading pulses. There was no effect of polarity on peak electrode location.These results indicate that for equal current levels, the anodic-leading polarity produces broader excitation patterns compared with cathodic-leading pulses, which reduces the spatial separation between functions. This result is likely due to preferential stimulation of the central axon. Further research is needed to determine whether SOE patterns obtained with anodic-leading pulses better predict pitch discrimination.

scholarly journals Psychophysical measures of tonotopic selectivity in cats and humans

2021 ◽  
Author(s):  
Robert P. Carlyon ◽  
John C. Middlebrooks ◽  
Matthew L. Richardson ◽  
Robin Gransier ◽  
François Guérit ◽  
...  
Keyword(s):  
Cochlear Implants ◽  
Pure Tone ◽  
Electrophysiological Study ◽  
Center Frequency ◽  
Auditory Prosthesis ◽  
Auditory Filter ◽  
Non Invasive ◽  
Spread Of Excitation ◽  
Novel Approaches ◽  
Electrophysiological Methods

Sound spectra are represented by patterns of activity along the tonotopic axis ofthe cochlea. Cochlear implants can transmit spectra by stimulating tonotopicallyappropriate electrodes, but fidelity is limited by intracochlear spread of excitation. We aim to better evaluate present-day experimental stimulation procedures and, potentially, to improve transmission of spectra with novel stimulation modalities. As a first step, we are developing non-invasive measures of tonotopic spread of excitation that can be compared between normal-hearing cats and humans. These measures include psychophysics in the present study and scalp-recorded electrophysiology in a companion study (Guérit et al., 2021). Cats and humans detected pure-tone probes presented in continuous 1/8- and 1-oct noise-band maskers. Masker bandwidths were readily discernable in both species by the dependence of masked thresholds on probe frequencies. Thresholds were largely constant across the bandwidth of the 1-oct masker, whereas thresholds dropped markedly at frequencies away from the center of the 1/8-oct masker. Cats and humans differed in that the feline auditory filter centered on 8 kHz, which we measured using a notched-noise procedure, was 22% wider than published values for humans at the same center frequency. Also, thresholds for the cats in the 1-octmasker condition consistently were 1.0 to 3.2 dB higher than expected based on the estimated masker power in the feline auditory filter. The present psychophysical results parallel those in our companion electrophysiological study, thereby providing perceptual validation for that study. These psychophysical and electrophysiological methods will be valuable for future investigations of novel approaches for auditory prosthesis.

Effects of Fundamental Frequency Contours on Sentence Recognition in Mandarin-Speaking Children With Cochlear Implants

2020 ◽  
Vol 63 (11) ◽  
pp. 3855-3864
Author(s):  
Wanting Huang ◽  
Lena L. N. Wong ◽  
Fei Chen ◽  
Haihong Liu ◽  
Wei Liang
Keyword(s):  
Cochlear Implants ◽  
Fundamental Frequency ◽  
Signal To Noise Ratio ◽  
Lexical Tone ◽  
Signal To Noise ◽  
Sentence Recognition ◽  
Test Conditions ◽  
Age Appropriate ◽  
F0 Contour ◽  
Appropriate Sentences

Purpose Fundamental frequency (F0) is the primary acoustic cue for lexical tone perception in tonal languages but is processed in a limited way in cochlear implant (CI) systems. The aim of this study was to evaluate the importance of F0 contours in sentence recognition in Mandarin-speaking children with CIs and find out whether it is similar to/different from that in age-matched normal-hearing (NH) peers. Method Age-appropriate sentences, with F0 contours manipulated to be either natural or flattened, were randomly presented to preschool children with CIs and their age-matched peers with NH under three test conditions: in quiet, in white noise, and with competing sentences at 0 dB signal-to-noise ratio. Results The neutralization of F0 contours resulted in a significant reduction in sentence recognition. While this was seen only in noise conditions among NH children, it was observed throughout all test conditions among children with CIs. Moreover, the F0 contour-induced accuracy reduction ratios (i.e., the reduction in sentence recognition resulting from the neutralization of F0 contours compared to the normal F0 condition) were significantly greater in children with CIs than in NH children in all test conditions. Conclusions F0 contours play a major role in sentence recognition in both quiet and noise among pediatric implantees, and the contribution of the F0 contour is even more salient than that in age-matched NH children. These results also suggest that there may be differences between children with CIs and NH children in how F0 contours are processed.

Age at Full-Time Use Predicts Language Outcomes Better Than Age of Surgery in Children Who Use Cochlear Implants

2019 ◽  
Vol 28 (4) ◽  
pp. 986-992 ◽  
Author(s):  
Lisa R. Park ◽  
Erika B. Gagnon ◽  
Erin Thompson ◽  
Kevin D. Brown
Keyword(s):  
Cochlear Implants ◽  
Time Use ◽  
Expressive Language ◽  
Normal Hearing ◽  
Full Time ◽  
Language Outcomes ◽  
Age At Surgery ◽  
Device Placement ◽  
Device Use ◽  
Better Than

Purpose The aims of this study were to (a) determine a metric for describing full-time use (FTU), (b) establish whether age at FTU in children with cochlear implants (CIs) predicts language at 3 years of age better than age at surgery, and (c) describe the extent of FTU and length of time it took to establish FTU in this population. Method This retrospective analysis examined receptive and expressive language outcomes at 3 years of age for 40 children with CIs. Multiple linear regression analyses were run with age at surgery and age at FTU as predictor variables. FTU definitions included 8 hr of device use and 80% of average waking hours for a typically developing child. Descriptive statistics were used to describe the establishment and degree of FTU. Results Although 8 hr of daily wear is typically considered FTU in the literature, the 80% hearing hours percentage metric accounts for more variability in outcomes. For both receptive and expressive language, age at FTU was found to be a better predictor of outcomes than age at surgery. It took an average of 17 months for children in this cohort to establish FTU, and only 52.5% reached this milestone by the time they were 3 years old. Conclusions Children with normal hearing can access spoken language whenever they are awake, and the amount of time young children are awake increases with age. A metric that incorporates the percentage of time that children with CIs have access to sound as compared to their same-aged peers with normal hearing accounts for more variability in outcomes than using an arbitrary number of hours. Although early FTU is not possible without surgery occurring at a young age, device placement does not guarantee use and does not predict language outcomes as well as age at FTU.

Overview of Current Approaches to Aural Rehabilitation for Adults With Cochlear Implants

2020 ◽  
Vol 5 (5) ◽  
pp. 1175-1187
Author(s):  
Rachel Glade ◽  
Erin Taylor ◽  
Deborah S. Culbertson ◽  
Christin Ray
Keyword(s):  
Health Care ◽  
Clinical Practice ◽  
Cochlear Implants ◽  
Practice Patterns ◽  
The United States ◽  
Care Providers ◽  
Aural Rehabilitation ◽  
Starting Point ◽  
Clinical Models ◽  
Hearing Health

Purpose This clinical focus article provides an overview of clinical models currently being used for the provision of comprehensive aural rehabilitation (AR) for adults with cochlear implants (CIs) in the Unites States. Method Clinical AR models utilized by hearing health care providers from nine clinics across the United States were discussed with regard to interprofessional AR practice patterns in the adult CI population. The clinical models were presented in the context of existing knowledge and gaps in the literature. Future directions were proposed for optimizing the provision of AR for the adult CI patient population. Findings/Conclusions There is a general agreement that AR is an integral part of hearing health care for adults with CIs. While the provision of AR is feasible in different clinical practice settings, service delivery models are variable across hearing health care professionals and settings. AR may include interprofessional collaboration among surgeons, audiologists, and speech-language pathologists with varying roles based on the characteristics of a particular setting. Despite various existing barriers, the clinical practice patterns identified here provide a starting point toward a more standard approach to comprehensive AR for adults with CIs.

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