Previous Experience as a Confounding Factor in Comparing Cochlear-Implant Processing Schemes

1986 ◽  
Vol 29 (2) ◽  
pp. 282-287 ◽  
Author(s):  
Richard S. Tyler ◽  
John P. Preece ◽  
Bruce J. Gantz ◽  
Steven R. Otto ◽  
Charissa R. Lansing
Keyword(s):  
Cochlear Implant ◽  
Hearing Aids ◽  
Speech Processing ◽  
Dynamic Range ◽  
Prior Experience ◽  
Previous Experience ◽  
Electrode Position ◽  
Formant Frequency ◽  
Processing Scheme ◽  
The Subject

It is of great importance to compare the relative merits of different cochlear-implant speech-processing strategies. Some groups have compared different strategies within single subjects, but usually the subject has prior experience with one strategy, and no allowance is made for this prior experience. We show in the present study that this is inappropriate. We tested one subject using the Melbourne (Cochlear Corp.) multichannel implant with the device set to process sounds in two different ways. In the first processing scheme, the device functioned normally, extracting information about voicing frequency, amplitude and second-formant frequency. This information activated the 21-channel device, determining pulse rate, pulse amplitude and electrode position (respectively). In the second processing scheme, a single electrode (with the largest dynamic range) was activated. This electrode coded overall amplitude and voicing frequency. The subject was tested on an audiovisual test of a 14-choice consonant recognition in the form/iCi/ over a period of over 4 months. During this time the subject used the 21-channel processor outside of the laboratory. Upon initial connection, there was little difference between the results obtained with the two schemes when tested in sound alone or in sound plus vision. However, after about 4 months, scores obtained with the 21-channel processor in sound plus vigion were superior to the scores obtained with the one channel. This advantage came from a superiority in the features of voicing and nasality, but not place. Scores for sound-alone conditions between the two processing schemes remained similar for the 4-month period. Studies investigating the relative merits of speech processing systems (including tactile and conventional hearing aids) must consider previous experience as an important factor.

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.

Speech-Processing Strategies and Their Implementation

1987 ◽  
Vol 96 (1_suppl) ◽  
pp. 71-74 ◽  
Author(s):  
P. Seligman
Keyword(s):  
Cochlear Implant ◽  
Pulse Rate ◽  
Speech Processing ◽  
Temporal Coding ◽  
Electrode Position ◽  
Processing Strategy ◽  
Limited Information ◽  
Processing Strategies ◽  
Speech Information

Since 1979, the Australian speech-processing strategy has been based on the presentation of an estimate of F2 coded by electrode position and F0 coded by pulse rate. Although providing limited information, this strategy has produced good results with significant hearing-alone performance. This paper describes a number of strategies that provide further speech information in an attempt to increase hearing-alone performance to a level where the cochlear implant is able to operate in its own right rather than as an adjunct to lipreading. The strategies are all based on the addition of F1 to the existing strategy. Both electrode and temporal coding of F1 is described, and the performance and percepts produced are discussed. Amplitudes of the two formants must be carefully controlled to avoid masking. The implications of the strategies on the design of hardware are described.

Comparison of Multichannel Wide Dynamic Range Compression and ChannelFree Processing Strategies on Consonant Recognition

2015 ◽  
Vol 26 (07) ◽  
pp. 607-614 ◽  
Author(s):  
Patrick Plyler ◽  
Mark Hedrick ◽  
Brittany Rinehart ◽  
Rebekah Tripp
Keyword(s):  
Hearing Aids ◽  
Repeated Measures ◽  
Dynamic Range ◽  
Hearing Aid ◽  
Previous Experience ◽  
Wide Dynamic Range ◽  
Dynamic Range Compression ◽  
Processing Strategies ◽  
Hearing Aid Use ◽  
Subjective Preference

Background: Both wide dynamic range compression (WDRC) and ChannelFree (CF) processing strategies in hearing aids were designed to improve listener comfort and consonant identification, yet few studies have actually compared them. Purpose: To determine whether CF processing provides equal or better consonant identification and subjective preference than WDRC. Research Design: A repeated-measures randomized design was used in which each participant identified consonants from prerecorded nonsense vowel–consonant–vowel syllables in three conditions: unaided, aided using CF processing, and aided using WDRC processing. For each of the three conditions, syllables were presented in quiet and in a speech-noise background. Participants were also asked to rate the two processing schemes according to overall preference, preference in quiet and noise, and sound quality. Study Sample: Twenty adults (seven females; mean age 69.7 yr) with ≥1 yr of hearing aid use participated. Ten participants had previous experience wearing aids with WDRC, and 10 had previous experience with CF processing. Participants were tested with both WDRC and CF processing. Data Collection and Analysis: Number of consonants correct were measured and used as the dependent variable in analyses of variance with subsequent post hoc testing. For subjective preference, a listener rating form was employed with subsequent χ2 analysis. Results: Overall results showed that signal-processing strategy did not significantly affect consonant identification or subjective preference, nor did previous hearing aid use influence results. Listeners with audiometric slopes exceeding 11 dB per octave, however, preferred CF processing and performed better in noise with CF processing. Conclusion: CF processing is a viable alternative to WDRC for listeners with more severely sloping audiometric contours.

Performance of Cochlear Implant Patients as a Function of Time

1990 ◽  
Vol 33 (3) ◽  
pp. 511-519 ◽  
Author(s):  
Lynn G. Spivak ◽  
Susan B. Waltzman
Keyword(s):  
Speech Recognition ◽  
Speech Perception ◽  
Cochlear Implant ◽  
Hearing Aids ◽  
Prognostic Indicator ◽  
Processing Scheme ◽  
Open Set ◽  
Time Period ◽  
Recognition Ability ◽  
Over Time

The speech perception abilities of 15 patients were measured preoperatively using hearing aids and postoperatively using the Nucleus 22-channel cochlear implant over a period of 1, 2, or 3 years. Analysis of mean data revealed that, although the greatest amount of improvement in speech perception scores occurred between the preoperative and 3-month poststimulation evaluation, there was also significant improvement in perception of segmental features and open-set speech recognition over the 3-year time period. When individual patient data were examined, however, it was clear that these improvements were due, in large part, to the performance of a subset of patients who had measurable open-set speech recognition abilities at the time of their 3-month, poststimulation evaluation. Subjects who used the processing scheme that included coding of F1 showed significantly more improvement over time than subjects who used the original FOF2 processing scheme exclusively. It was concluded that open-set speech recognition ability at 3 months is an important prognostic indicator of continued improvement in speech perception abilities over time.

scholarly journals The Relationship Between Impedance, Programming and Word Recognition in a Large Clinical Dataset of Cochlear Implant Recipients

2022 ◽  
Vol 26 ◽  
pp. 233121652110609
Author(s):  
Benjamin Caswell-Midwinter ◽  
Elizabeth M. Doney ◽  
Meisam K. Arjmandi ◽  
Kelly N. Jahn ◽  
Barbara S. Herrmann ◽  
...  
Keyword(s):  
Word Recognition ◽  
Cochlear Implant ◽  
Speech Processing ◽  
Dynamic Range ◽  
Electrode Impedance ◽  
Current Steering ◽  
Processing Strategy ◽  
Monosyllabic Word ◽  
Negatively Associated ◽  
Clinical Dataset

Cochlear implant programming typically involves measuring electrode impedance, selecting a speech processing strategy and fitting the dynamic range of electrical stimulation. This study retrospectively analyzed a clinical dataset of adult cochlear implant recipients to understand how these variables relate to speech recognition. Data from 425 implanted post-lingually deafened ears with Advanced Bionics devices were analyzed. A linear mixed-effects model was used to infer how impedance, programming and patient factors were associated with monosyllabic word recognition scores measured in quiet. Additional analyses were conducted on subsets of data to examine the role of speech processing strategy on scores, and the time taken for the scores of unilaterally implanted patients to plateau. Variation in basal impedance was negatively associated with word score, suggesting importance in evaluating the profile of impedance. While there were small, negative bivariate correlations between programming level metrics and word scores, these relationships were not clearly supported by the model that accounted for other factors. Age at implantation was negatively associated with word score, and duration of implant experience was positively associated with word score, which could help to inform candidature and guide expectations. Electrode array type was also associated with word score. Word scores measured with traditional continuous interleaved sampling and current steering speech processing strategies were similar. The word scores of unilaterally implanted patients largely plateaued within 6-months of activation. However, there was individual variation which was not related to initially measured impedance and programming levels.

Psychophysical and Speech Studies with an Electrotactile Speech Processor

1987 ◽  
Vol 96 (1_suppl) ◽  
pp. 87-89 ◽  
Author(s):  
P. J. Blamey
Keyword(s):  
Cochlear Implant ◽  
Pulse Rate ◽  
Pulse Width ◽  
Speech Comprehension ◽  
Electrode Position ◽  
Speech Discrimination ◽  
Formant Frequency ◽  
Speech Processor ◽  
Multiple Channel ◽  
Second Formant

A multiple-channel electrotactile speech processor worn on the fingers of one hand has been constructed. This processor implements a speech-coding strategy that presents the second formant frequency by electrode position, fundamental frequency by electrical pulse rate, and amplitude envelope by pulse width. This strategy is similar to the one used by the Nucleus cochlear implant. Psychophysical tests with normally hearing and profoundly deaf subjects have measured the discrimination of stimuli differing in pulse rate, electrode, or pulse width. The levels of performance were comparable to those for cochlear implant patients except for pulse rate discrimination. Three untrained normally hearing adults using electrotactile stimulation without hearing or lipreading scored significantly better than chance for a range of two alternative forced-choice speech discrimination tasks. Provided that subjects can learn to associate linguistically meaningful concepts with tactile sensations, an improved level of speech comprehension may be achieved when the electrotactile speech processor is used together with lipreading.

Auditory Cortical Images of Cochlear-Implant Stimuli: Coding of Stimulus Channel and Current Level

2002 ◽  
Vol 87 (1) ◽  
pp. 493-507 ◽  
Author(s):  
John C. Middlebrooks ◽  
Julie Arenberg Bierer
Keyword(s):  
Auditory Cortex ◽  
Cochlear Implant ◽  
Speech Processing ◽  
Common Ground ◽  
Dynamic Range ◽  
Current Level ◽  
Physiological Data ◽  
Cochlear Prosthesis ◽  
Active Electrode ◽  
Stimulus Current

This study quantified the accuracy with which populations of neurons in the auditory cortex can represent aspects of electrical cochlear stimuli presented through a cochlear implant. We tested the accuracy of coding of the place of stimulation (i.e., identification of the active stimulation channel) and of the stimulus current level. Physiological data came from the companion study, which recorded spike activity of neurons simultaneously from 16 sites along the tonotopic axis of the guinea pig's auditory cortex. In that study, cochlear electrical stimuli were presented to acutely deafened animals through a 6-electrode animal version of the 22-electrode Nucleus banded electrode array (Cochlear). Cochlear electrode configurations consisted of monopolar (MP), bipolar (BP + N) with N inactive electrodes between the active and return electrodes (0 ≤ N ≤ 3), tripolar (TP) with one active electrode and two flanking return electrodes, and common ground (CG) with one active electrode and as many as five return electrodes. In the present analysis, an artificial neural network was trained to recognize spatiotemporal patterns of cortical activity in response to single presentations of particular stimuli and, thereby, to identify those stimuli. The accuracy of pair-wise discrimination of stimulation channels or of current levels was represented by the discrimination index, d′, where d′ = 1 was taken as threshold. In many cases, the threshold for discrimination of place of cochlear stimulation was <0.75 mm, and the threshold for discrimination of current levels was <1 dB. Cochlear electrode configurations varied in the accuracy with which they signaled to the auditory cortex the place of cochlear stimulation. The BP + N and TP configurations provided considerably greater sensitivity to place of stimulation than did the MP configuration. The TP configuration maintained accurate signaling of place of stimulation up to the highest current levels, whereas sensitivity was degraded at high current levels in BP + N configurations. Electrode configurations also varied in the dynamic range over which they signaled stimulus current level. Dynamic ranges were widest for the BP + 0 configuration and narrowest for the TP configuration. That is, the configuration that showed the most accurate signaling of cochlear place of stimulation (TP) showed the most restricted dynamic range for signaling of current level. These results suggest that the choice of the optimal electrode configuration for use by human cochlear-prosthesis users would depend on the particular demands of the speech-processing strategy that is to be employed.

scholarly journals Impact of Electrode Position on the Dynamic Range of a Human Auditory Nerve Fiber

2021 ◽  
Author(s):  
Frank Rattay ◽  
Thomas Tanzer
Keyword(s):  
Cochlear Implant ◽  
Nerve Fiber ◽  
Auditory Nerve ◽  
Dynamic Range ◽  
Acoustic Stimulation ◽  
Nerve Fibers ◽  
Auditory Nerve Fiber ◽  
Electrode Position ◽  
Insertion Depth ◽  
Firing Efficiency

Abstract Electrodes of a cochlear implant generate spikes in auditory nerve fibers. While the insertion depth of each of the electrodes is linked to a frequency section of the acoustic signal, the amplitude of the stimulating pulses controls the loudness of the related frequency band. The firing efficiency of an auditory nerve fiber, stimulated by a train of pulses varies between 0 and 100%. 100% firing efficiency means every pulse elicits a spike, 50% defines threshold. The dynamic range of an auditory nerve fiber is the range of stimulus intensities that causes a firing probability between 10 and 90%. This ‘electrical’ dynamic range is quite small in comparison to the variation of spiking rates measured during acoustic stimulation. Consequently, an increased dynamic range may improve the quality of auditory perception for cochlear implant users. Electrodes are often placed as close as possible to the center axis of the cochlea. Analysis of simulated auditory nerve firing showed that this placement is disadvantageous for the dynamic range. Five times larger dynamic ranges are expected for electrodes close to the terminal of the dendrite or at mid-dendritic placement.

Effect of different input dynamic range variables on cochlear implant performance in postlingual cochlear implant in adults

2019 ◽  
Vol 69 (3) ◽  
Author(s):  
Tarek A. Ghannoum ◽  
Mona H. Selim ◽  
Amira M. El-Shennawy ◽  
Zahraa M. Elbohy
Keyword(s):  
Cochlear Implant ◽  
Dynamic Range

scholarly journals Cochlear Implant Research and Development in the Twenty-first Century: A Critical Update

2021 ◽  
Vol 22 (5) ◽  
pp. 481-508
Author(s):  
Robert P. Carlyon ◽  
Tobias Goehring
Keyword(s):  
Research And Development ◽  
Patient Outcomes ◽  
Speech Processing ◽  
Turn Of The Century ◽  
First Century ◽  
Directional Microphones ◽  
Wide Range ◽  
The Subject ◽  
Processing Algorithms ◽  
Improve Patient

AbstractCochlear implants (CIs) are the world’s most successful sensory prosthesis and have been the subject of intense research and development in recent decades. We critically review the progress in CI research, and its success in improving patient outcomes, from the turn of the century to the present day. The review focuses on the processing, stimulation, and audiological methods that have been used to try to improve speech perception by human CI listeners, and on fundamental new insights in the response of the auditory system to electrical stimulation. The introduction of directional microphones and of new noise reduction and pre-processing algorithms has produced robust and sometimes substantial improvements. Novel speech-processing algorithms, the use of current-focusing methods, and individualised (patient-by-patient) deactivation of subsets of electrodes have produced more modest improvements. We argue that incremental advances have and will continue to be made, that collectively these may substantially improve patient outcomes, but that the modest size of each individual advance will require greater attention to experimental design and power. We also briefly discuss the potential and limitations of promising technologies that are currently being developed in animal models, and suggest strategies for researchers to collectively maximise the potential of CIs to improve hearing in a wide range of listening situations.

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