Effect of electrode configuration on psychophysical forward masking in cochlear implant listeners

2006 ◽  
Vol 119 (5) ◽  
pp. 2994-3002 ◽  
Author(s):  
Bom Jun Kwon ◽  
Chris van den Honert
Keyword(s):  
Cochlear Implant ◽  
Forward Masking ◽  
Electrode Configuration

scholarly journals Effect of pulse phase duration on forward masking and spread of excitation in cochlear implant listeners

PLoS ONE ◽  
2020 ◽  
Vol 15 (7) ◽  
pp. e0236179
Author(s):  
Ning Zhou ◽  
Zhen Zhu ◽  
Lixue Dong ◽  
John J. Galvin
Keyword(s):  
Cochlear Implant ◽  
Forward Masking ◽  
Phase Duration ◽  
Pulse Phase ◽  
Spread Of Excitation

An objective method to measure electrode independence in cochlear implant patients with a dual-masker forward masking technique

2009 ◽  
Vol 253 (1-2) ◽  
pp. 3-14 ◽  
Author(s):  
W. Martin C. Klop ◽  
Johan H.M. Frijns ◽  
Wim Soede ◽  
Jeroen J. Briaire
Keyword(s):  
Cochlear Implant ◽  
Forward Masking ◽  
Objective Method

Efficacy of a Cochlear Implant Simultaneous Analog Stimulation Strategy Coupled with a Monopolar Electrode Configuration

2005 ◽  
Vol 114 (11) ◽  
pp. 886-893 ◽  
Author(s):  
Li Xu ◽  
Teresa A. Zwolan ◽  
Catherine S. Thompson ◽  
Bryan E. Pfingst
Keyword(s):  
Speech Recognition ◽  
Cochlear Implant ◽  
Speech Processing ◽  
Dynamic Range ◽  
Recognition Performance ◽  
Electrode Configuration ◽  
Processing Strategy ◽  
Open Set ◽  
Hearing In Noise ◽  
Noise Test

Objectives: The present study was performed to evaluate the efficacy and clinical feasibility of using monopolar stimulation with the Clarion Simultaneous Analog Stimulation (SAS) strategy in patients with cochlear implants. Methods: Speech recognition by 10 Clarion cochlear implant users was evaluated by means of 4 different speech processing strategy/electrode configuration combinations; ie, SAS and Continuous Interleaved Sampling (CIS) strategies were each used with monopolar (MP) and bipolar (BP) electrode configurations. The test measures included consonants, vowels, consonant-nucleus-consonant words, and Hearing in Noise Test sentences with a +10 dB signal-to-noise ratio. Additionally, subjective judgments of sound quality were obtained for each strategy/configuration combination. Results: All subjects but 1 demonstrated open-set speech recognition with the SAS/MP combination. The group mean Hearing in Noise Test sentence score for the SAS/MP combination was 31.6% (range, 0% to 92%) correct, as compared to 25.0%, 46.7%, and 37.8% correct for the CIS/BP, CIS/MP, and SAS/BP combinations, respectively. Intersubject variability was high, and there were no significant differences in mean speech recognition scores or mean preference ratings among the 4 strategy/configuration combinations tested. Individually, the best speech recognition performance was with the subject's everyday strategy/configuration combination in 72% of the applicable cases. If the everyday strategy was excluded from the analysis, the subjects performed best with the SAS/MP combination in 37.5% of the remaining cases. Conclusions: The SAS processing strategy with an MP electrode configuration gave reasonable speech recognition in most subjects, even though subjects had minimal previous experience with this strategy/configuration combination. The SAS/MP combination might be particularly appropriate for patients for whom a full dynamic range of electrical hearing could not be achieved with a BP configuration.

scholarly journals SpeedCAP: An Efficient Method for Estimating Neural Activation Patterns Using Electrically-Evoked Compound Action-Potentials in Cochlear Implant Users

2021 ◽  
Author(s):  
Charlotte Garcia ◽  
John M. Deeks ◽  
Tobias Goehring ◽  
Daniele Borsetto ◽  
Manohar Bance ◽  
...  
Keyword(s):  
Data Collection ◽  
Cochlear Implant ◽  
Action Potentials ◽  
Forward Masking ◽  
Patient Specific ◽  
Neural Activation ◽  
Current Spread ◽  
Wide Range ◽  
Compound Action Potentials ◽  
Compound Action

Objectives: Electrically-Evoked Compound Action-Potentials (ECAPs) can be recorded using the electrodes in a cochlear implant (CI) and represent the synchronous responses of the electrically-stimulated auditory-nerve. ECAPs can be obtained using a forward-masking method that measures the neural response to a probe and masker electrode separately and in combination. The Panoramic ECAP (PECAP) method measures ECAPs using multiple combinations of masker and probe electrodes and uses a nonlinear optimization algorithm to estimate current spread from each electrode and neural health along the cochlea. However, the measurement of ECAPs from multiple combinations of electrodes is too time-consuming for use in clinics. This study proposes and evaluates a fast version of the PECAP measurements, SpeedCAP, that minimises recording time by exploiting redundancies between multiple ECAP measures, and that can be applied to methods where multiple ECAPs are required. Design: In the first study, 11 users of Cochlear Limited CIs took part. ECAPs were recorded using the forward-masking artefact-cancellation technique at the most comfortable loudness level (MCL) for every combination of masker and probe electrodes for all active electrodes in the users’ MAPs, as per the standard PECAP recording paradigm. The same current levels and recording parameters were then used to collect ECAPs in the same users with the SpeedCAP method. The ECAP amplitudes were then compared between the two conditions, as were the corresponding estimates of neural health and current spread calculated using the PECAP method described by Garcia et al (2021). The second study measured SpeedCAP intra-operatively in 8 CI patients and with all maskers and probes presented at the same current level to assess feasibility. ECAPs for the subset of conditions where the masker and probe were presented on the same electrode were compared to those obtained using the slower approach leveraged by the standard clinical software. Results: Data collection time was reduced from 45 (PECAP) to 8 (SpeedCAP) minutes. There were no significant differences between normalized root mean squared error (RMSE) repeatability metrics for post-operative PECAP and SpeedCAP data, nor for the RMSEs calculated between PECAP and SpeedCAP data. When between-participant differences were removed, both the neural health (r = 0.73) and current spread (r = 0.65) estimates were significantly correlated (p < 0.0001, df = 218) between SpeedCAP and PECAP conditions across all electrodes. Valid ECAPs were obtained in all patients in the second study, demonstrating intra-operative feasibility of SpeedCAP. No significant differences in RMSEs were detectable between post- and intra-operative ECAP measurements. Conclusions: The improved efficiency of SpeedCAP provides time savings facilitating multi-electrode ECAP recordings in routine clinical practice. The SpeedCAP data collection is sufficiently quick to record intra-operatively, and adds no significant error to the ECAP amplitudes. Such measurements could thereafter be submitted to models such as PECAP to provide patient-specific patterns of neural activation to inform programming of clinical MAPs and/or identify causes of poor performance at the electrode-nerve interface of CI users. The speed and accuracy of these measurements also opens up a wide range of additional research questions to be addressed.

scholarly journals Cochlear-Implant High Pulse Rate and Narrow Electrode Configuration Impair Transmission of Temporal Information to the Auditory Cortex

2008 ◽  
Vol 100 (1) ◽  
pp. 92-107 ◽  
Author(s):  
John C. Middlebrooks
Keyword(s):  
Animal Model ◽  
Auditory Cortex ◽  
Cochlear Implant ◽  
Pulse Rate ◽  
Temporal Information ◽  
Electrode Configuration ◽  
Bipolar Electrode ◽  
Pulse Trains ◽  
Speech Reception ◽  
High Pulse

In the most commonly used cochlear prosthesis systems, temporal features of sound are signaled by amplitude modulation of constant-rate pulse trains. Several convincing arguments predict that speech reception should be optimized by use of pulse rates ≳2,000 pulses per second (pps) and by use of intracochlear electrode configurations that produce restricted current spread (e.g., bipolar rather than monopolar configurations). Neither of those predictions has been borne out in consistent improvements in speech reception. Neurons in the auditory cortex of anesthetized guinea pigs phase lock to the envelope of sine-modulated electric pulse trains presented through a cochlear implant. The present study used that animal model to quantify the effects of carrier pulse rate, electrode configuration, current level, and modulator wave shape on transmission of temporal information from a cochlear implant to the auditory cortex. Modulation sensitivity was computed using a signal-detection analysis of cortical phase-locking vector strengths. Increasing carrier pulse rate in 1-octave steps from 254 to 4,069 pps resulted in systematic decreases in sensitivity. Comparison of sine- versus square-wave modulator waveforms demonstrated that some, but not all, of the loss of modulation sensitivity at high pulse rates was a result of the decreasing size of pulse-to-pulse current steps at the higher rates. Use of a narrow bipolar electrode configuration, compared with the monopolar configuration, produced a marked decrease in modulation sensitivity. Results from this animal model suggest explanations for the failure of high pulse rates and/or bipolar electrode configurations to produce hoped-for improvements in speech reception.

scholarly journals Forward masking studies on a multichannel cochlear implant patient

1986 ◽  
Vol 80 (S1) ◽  
pp. S29-S30 ◽  
Author(s):  
H. H. Lim ◽  
Y. C. Tong ◽  
G. M. Clark ◽  
P. A. Busby
Keyword(s):  
Cochlear Implant ◽  
Forward Masking

scholarly journals Partial tripolar cochlear implant stimulation: Spread of excitation and forward masking in the inferior colliculus

2010 ◽  
Vol 270 (1-2) ◽  
pp. 134-142 ◽  
Author(s):  
Julie Arenberg Bierer ◽  
Steven M. Bierer ◽  
John C. Middlebrooks
Keyword(s):  
Cochlear Implant ◽  
Inferior Colliculus ◽  
Forward Masking ◽  
Spread Of Excitation
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