A Web-Based Automated Image Processing Research Platform for Cochlear Implantation-Related Studies.

The robust delineation of the cochlea and its inner structures combined with the detection of the electrode of a cochlear implant within these structures is essential for envisaging a safer, more individualized, routine image-guided cochlear implant therapy. We present Nautilus-a web-based research platform for automated pre- and post-implantation cochlear analysis. Nautilus delineates cochlear structures from pre-operative clinical CT images by combining deep learning and Bayesian inference approaches. It enables the extraction of electrode locations from a post-operative CT image using convolutional neural networks and geometrical inference. By fusing pre- and post-operative images, Nautilus is able to provide a set of personalized pre- and post-operative metrics that can serve the exploration of clinically relevant questions in cochlear implantation therapy. In addition, Nautilus embeds a self-assessment module providing a confidence rating on the outputs of its pipeline. We present a detailed accuracy and robustness analyses of the tool on a carefully designed dataset. The results of these analyses provide legitimate grounds for envisaging the implementation of image-guided cochlear implant practices into routine clinical workflows.

Clinical experiences with intraoperative electrocochleography in cochlear implant recipients and its potential to reduce insertion trauma and improve postoperative hearing preservation.

Access to low-frequency acoustic information in cochlear implant patients leads to better speech understanding in noise. Electrocochleography (ECochG) can provide real-time feedback about the health of the cochlea during the insertion process with the potential to reduce insertion trauma. We describe our experiences of using this technique. Data from 47 adult subjects with measurable residual hearing and an Advanced Bionics (Valencia, CA) SlimJ (46) or MidScala (1) electrode array were analyzed. ECochGs were recorded intraoperatively via the implant. The surgeon adjusted the course of the electrode insertion based on drops in the ECochG. The final array position was assessed using postoperative imaging and pure tone thresholds were measured before and after surgery. Three different patterns of ECochG response amplitude were observed: Growth, Fluctuating and Total Loss. Subjects in the growth group showed the smallest postoperative hearing loss. However, the group with fluctuating amplitudes showed no meaningful correlation between the ECochG responses and the postoperative hearing loss, indicating that amplitude alone is insufficient for detecting damage. Considering the phase of the signal additionally to the amplitude and reclassifying the data by both the phase and amplitude of the response into three groups Type I-Type III produced statistically significant correlations between postoperative hearing loss and the grouping based on amplitude and phase respectively. We showed significantly better hearing preservation for Type I (no drop in amplitude) and Type II (drop with a concurrent phase shift), while Type III (drop without concurrent phase shift) had more surgery induced hearing loss. ECochG potentials measured through the implant could provide valuable feedback during the electrode insertion. Both the amplitude and phase of the ECochG response are important to consider. More data needs to be evaluated to better understand the impact of the different signal components to design an automated system to alert the surgeon ahead of damaging the cochlea.

Relationship Between Intraoperative Electrocochleography and Hearing Preservation.

OBJECTIVES: To compare intraoperative intracochlear electrocochleography (ECochG) with hearing preservation outcomes in cochlear implant (CI) subjects. DESIGN: Intraoperative electrocochleography was performed in adult CI subjects who were recipients of Advanced Bionics' Bionics LLC precurved HiFocus MidScala or straight HiFocus SlimJ electrode arrays. ECochG responses were recorded from the most apical electrode contact during insertion. No changes to the insertions were made due to ECochG monitoring. No information about insertion resistance was collected. ECochG drops were estimated as the change in amplitude from peak (defined as maximum amplitude response) to drop (largest drop) point after the peak during insertion was measured following the peak response. Audiometric thresholds from each subject were obtained before and approximately 1 month after CI surgery. The change in pure tone average for frequencies between 125 Hz and 500 Hz was measured after surgery. No postoperative CT scans were collected as part of this study. RESULTS: A total of 68 subjects from five surgical centers participated in the study. The study sample included 30 MidScala and 38 SlimJ electrodes implanted by approximately 20 surgeons who contributed to the study. Although a wide range of results were observed, there was a moderate positive correlation (Pearson Correlation coefficient, r = 0.56, p < 0.01) between the size of the ECochG drop and the magnitude of pure tone average change. This trend was present for both the MidScala and SlimJ arrays. The SlimJ and MidScala arrays produced significantly different hearing loss after surgery. CONCLUSION: Large ECochG amplitude drops observed during electrode insertion indicated poorer hearing preservation. Although the outcomes were variable, this information may be helpful to guide surgical decision-making when contemplating full electrode insertion and the likelihood of hearing preservation.

Predictive models for cochlear implant outcomes: Performance, generalizability, and the impact of cohort size.

While cochlear implants have helped hundreds of thousands of individuals, it remains difficult to predict the extent to which an individual's hearing will benefit from implantation. Several publications indicate that machine learning may improve predictive accuracy of cochlear implant outcomes compared to classical statistical methods. However, existing studies are limited in terms of model validation and evaluating factors like sample size on predictive performance. We conduct a thorough examination of machine learning approaches to predict word recognition scores (WRS) measured approximately 12 months after implantation in adults with post-lingual hearing loss. This is the largest retrospective study of cochlear implant outcomes to date, evaluating 2,489 cochlear implant recipients from three clinics. We demonstrate that while machine learning models significantly outperform linear models in prediction of WRS, their overall accuracy remains limited (mean absolute error: 17.9-21.8). The models are robust across clinical cohorts, with predictive error increasing by at most 16% when evaluated on a clinic excluded from the training set. We show that predictive improvement is unlikely to be improved by increasing sample size alone, with doubling of sample size estimated to only increasing performance by 3% on the combined dataset. Finally, we demonstrate how the current models could support clinical decision making, highlighting that subsets of individuals can be identified that have a 94% chance of improving WRS by at least 10% points after implantation, which is likely to be clinically meaningful. We discuss several implications of this analysis, focusing on the need to improve and standardize data collection.

A sound coding strategy based on a temporal masking model for cochlear implants.

Auditory masking occurs when one sound is perceptually altered by the presence of another sound. Auditory masking in the frequency domain is known as simultaneous masking and in the time domain is known as temporal masking or non-simultaneous masking. This works presents a sound coding strategy that incorporates a temporal masking model to select the most relevant channels for stimulation in a cochlear implant (CI). A previous version of the strategy, termed psychoacoustic advanced combination encoder (PACE), only used a simultaneous masking model for the same purpose, for this reason the new strategy has been termed temporal-PACE (TPACE). We hypothesized that a sound coding strategy that focuses on stimulating the auditory nerve with pulses that are as masked as possible can improve speech intelligibility for CI users. The temporal masking model used within TPACE attenuates the simultaneous masking thresholds estimated by PACE over time. The attenuation is designed to fall exponentially with a strength determined by a single parameter, the temporal masking half-life T½. This parameter gives the time interval at which the simultaneous masking threshold is halved. The study group consisted of 24 postlingually deaf subjects with a minimum of six months experience after CI activation. A crossover design was used to compare four variants of the new temporal masking strategy TPACE (T½ ranging between 0.4 and 1.1 ms) with respect to the clinical MP3000 strategy, a commercial implementation of the PACE strategy, in two prospective, within-subject, repeated-measure experiments. The outcome measure was speech intelligibility in noise at 15 to 5 dB SNR. In two consecutive experiments, the TPACE with T½ of 0.5 ms obtained a speech performance increase of 11% and 10% with respect to the MP3000 (T½ = 0 ms), respectively. The improved speech test scores correlated with the clinical performance of the subjects: CI users with above-average outcome in their routine speech tests showed higher benefit with TPACE. It seems that the consideration of short-acting temporal masking can improve speech intelligibility in CI users. The half-live with the highest average speech perception benefit (0.5 ms) corresponds to time scales that are typical for neuronal refractory behavior.

The perception of the stereo effect in bilateral and bimodal cochlear implant users and its contribution to music enjoyment.

OBJECTIVES: In this clinical study, stereo perception of music samples and its contribution to music enjoyment in CI users is investigated. It is studied in free field as well as direct audio presentation. METHODS: 20 bilateral and 9 bimodal CI users performed stereo detection tests and music enjoyment ratings. Music was presented either in mono or in stereo in free field or with direct audio presentation. Stereo detection was assessed with a 3-AFC paradigm. Music enjoyment was studied with scale ratings. RESULTS: For bilateral CI users, stereo detection increased from 52% correct in free field to 86% with direct audio presentation. Increased music enjoyment with improved stereo detection was obtained. Bimodal CI users could not identify stereo sounds. Music enjoyment did not increase for stereo presentations in bimodal subjects. DISCUSSION: For bilateral CI users, improved stereo detection might increase music enjoyment with direct audio presentation, which is likely due to bypassing the room acoustics. In bimodal CI users, no clear improvement was found, which is likely attributed due to the different hearing losses and therefore individually different interaural frequency overlaps between the hearing aid and the cochlear implant. CONCLUSION: Direct audio presentation is an efficient method to improve music enjoyment in bilateral CI users.

Hearing Preservation With a New Atraumatic Lateral Wall Electrode.

INTRODUCTION: Many individuals have some residual hearing which should be preserved with cochlear implantation. To achieve this goal electrode arrays must fulfil certain design requirements. A new thin lateral wall electrode array (HiFocus SlimJ) was systematically designed on the basis of µCT studies of human cochlea anatomy. The primary objective of this study was to report on initial retrospective hearing preservation results from a cohort of subjects consecutively implanted with this electrode. Secondary objectives were to report on insertion depth and speech perception results for this new array. METHODS: Twenty subjects with considerable residual hearing in low frequencies were consecutively implanted with the SlimJ electrode array. The electrode was inserted slowly through the round window and the insertion process was controlled by intracochlear electrocochleography measuring cochlear microphonics through the cochlear implant.Postoperative cone beam computed tomography was conducted and precise scalar location and angular insertion depth was estimated following image fusion with the preoperative images. RESULTS: Low frequency hearing at 1 month postsurgery was preserved within 30 dB HL in 85% of subjects and within 15 dB HL in 50% of subjects. Mean angular insertion depth was 393 degrees (SD 62 degrees) with a range from 294 to 520 degrees. All electrode contacts in all subjects were identified within scala tympani. CONCLUSION: The SlimJ electrode array is easy to handle for atraumatic insertion through the round window, adjusted insertion depth controlled by electrocochleography measurements, and reliable fixation at the posterior tympanotomy. Hearing preservation rates are encouraging on the short term. We aim to further report on larger data sets and long-term outcomes.

Cochlear implantation in children with meningitis related deafness: The influence of electrode impedance and implant charge on auditory performance - A case control study.

OBJECTIVES: Bacterial meningitis can cause a labyrinthitis. Consequences often are intracochlear soft tissue neoformation (cochlear obliteration) or intracochlear osteoneogenesis (cochlear ossification) and deafness. Cochlear implantation becomes challenging and hearing rehabilitation is complicated. This retrospective case-control-study aimed to find correlations between morphologic, electric and functional parameters. METHODS: The study group included children, who lost hearing due to a bacterial meningitis (n = 35 cases). Using preoperative computed tomography and intraoperative findings we grouped into 'unaltered cochleae', 'obliterated cochleae' and 'ossified cochleae'. Control group children suffered from deafness (n = 16) of other aetiology and presented with radiologically unchanged cochleae. Postoperative routine controls documented impedances, stimulation charge and hearing tests a various time points, which all were analysed. RESULTS: Control group patients showed a mean impedance of 6.3 kΩ and the mean charge applied was 19 nC. The study group averaged at 7.9 kΩ and 24.6 nC respectively. Patients with ossified cochleae had increased values of 8.6 kΩ and 29.7 nC. The control group reached a monosyllabic word understanding of 74% and the study group of 58%. Patients with ossified cochleae reached 36%. CONCLUSIONS: Impedances and stimulation charge influence each other. Increased charge is necessary for higher cochlear implant output. Despite higher charges, patients with obliterated and patients with ossified cochleae significantly perform worse in hearing rehabilitation. Reduced audiological outcome in study group patients without morphologic cochlear changes furthermore hints at additional factors besides cochlear tissue neogenesis like postinflammational changes at the neural pathway.

Outcome evaluation on cochlear implant users with residual hearing.

OBJECTIVES: The performance outcome with Freedom™ Hybrid™ versus the CP900 series sound processor with Hybrid Hearing was investigated. In addition, a preliminary evaluation was conducted to consider the feasibility of upgrading experienced electric-only cochlear implant (CI) users who had substantial residual hearing to Hybrid Hearing. METHODS: This study was a single-centre prospective, non-inferiority design with repeated measures conducted at Hannover Medical School (MHH). The randomized AABB cross-over design to compensate for learning effects included two test groups. Group 1 compared two systems for Hybrid Hearing (Freedom Hybrid sound processor versus CP900 series sound processor) and Group 2 compared CP900 series sound processor (electric-only) versus the CP900 with Hybrid Hearing in experienced CI users who had confirmed residual low-frequency hearing. Groups 1 and 2 were composed of different participants. RESULTS: Group 1 (n = 24) performance on speech perception tests was equivalent or superior with the CP900 series sound processor showing a statistically significant mean improvement of 1.87 dB in background noise (P < 0.001). The mean speech understanding in quiet showed a better performance by 5% (P = 0.064) for participants tested with the CP900. The patient-reported outcome questionnaire confirmed the beneficial performance with the CP900 series sound processor with Hybrid Hearing. The feasibility portion of the study (Group 2, n = 14) showed an average benefit of 0.54 dB in background noise when using the CP900 with Hybrid Hearing function versus electric-only stimulation. CONCLUSIONS: The outcome presents sufficient evidence to show the effectiveness of the CP900 series sound processor with Hybrid Hearing over the Freedom Hybrid for participants with substantial residual hearing. Positive outcomes were observed for improved speech understanding and subjective hearing performance. Further, a trend was demonstrated in the data towards better performance with CP900 with Hybrid Hearing versus electric-only stimulation. Hybrid Hearing users showed a clinically relevant and statistically a significant benefit from the current CP900 series sound processor generation supporting its recommendation, on a case-by-case basis, to current electric-only users. More research is needed to confirm these findings.

Transient Noise Reduction in Cochlear Implant Users: a Multi-Band Approach.

A previously-tested transient noise reduction (TNR) algorithm for cochlear implant (CI) users was modified to detect and attenuate transients independently across multiple frequency-bands. Since speech and transient noise are often spectrally distinct, we hypothesized that benefits in speech intelligibility can be achieved over the earlier single-band design. Fifteen experienced CI users (49 to 72 years) were tested unilaterally using pre-processed stimuli delivered directly to a speech processor. Speech intelligibility in transient and soft stationary noise, subjective sound quality and the recognition of warning signals was investigated in three processing conditions: no TNR (TNRoff), single-band TNR (TNRsgl) and multi-band TNR (TNRmult). Notably, TNRmult improved speech reception thresholds (SRTs) in cafeteria noise and office noise by up to 3 dB over both TNRoff and TNRsgl, and yielded higher comfort and clarity ratings in cafeteria noise. Our results indicate that multi-band transient noise reduction may be advantageous compared to a single-band approach, and reveal a substantial overall potential for TNR to improve speech perception and listening comfort in CI users.

Deeper Cochlear Implant Electrode Insertion Angle Improves Detection of Musical Sound Quality Deterioration Related to Bass Frequency Removal.

BACKGROUND: Cochlear implant (CI) electrode arrays typically do not reach the most apical regions of the cochlea that intrinsically encode low frequencies. This may contribute to diminished implant-mediated musical sound quality perception. The objective of this study was to assess the effect of varying degrees of apical cochlear stimulation (measured by angular insertion depth) on musical sound quality discrimination. HYPOTHESIS: Increased apical cochlear stimulation will improve low-frequency perception and musical sound quality discrimination. METHODS: Standard (31.5 mm, n = 17) and medium (24 mm, n = 8) array Med-EL CI users, and normal hearing (NH) listeners (n = 16) participated. Imaging confirmed angular insertion depth. Participants completed a musical discrimination task in which they listened to a real-world musical stimulus (labeled reference) and provided sound quality ratings to versions of the reference, which included a hidden reference and test stimuli with increasing amounts of low-frequency removal. Scores for each CI users were calculated on the basis of how much their ratings differed from NH listeners for each stimulus version. RESULTS: Medium array and standard users had significantly different insertion depths (389.4 ± 64.5 and 583.9 ± 78.5 degrees, respectively; p <  .001). A significant Pearson's correlation was observed between angular insertion depth and the hidden reference scores (p < 0.05). CONCLUSION: CI users with greater apical stimulation made sound quality discriminations that more closely resembled those of NH controls for stimuli that contained low frequencies (< 200 Hz of information). These findings suggest that increased apical cochlear stimulation improves musical low-frequency perception, which may provide a more satisfactory music listening experience for CI users.

Evaluation of the 'Fitting to Outcomes eXpert' (FOX®) with established cochlear implant users.

OBJECTIVES: To evaluate the possible impact of 'Fitting to Outcomes eXpert (FOX(®))' on cochlear implant (CI) fitting in a clinic with extensive experience of fitting a range of CI systems, as a way to assess whether a software tool such as FOX is able to complement standard clinical procedures. METHODS: Ten adult post-lingually deafened and unilateral long-term users of the Advanced Bionics(TM) CI system (Clarion CII or HiRes 90K(TM)) underwent speech perception assessment with their current clinical program. One cycle 'iteration' of FOX optimization was performed and the program adjusted accordingly. After a month of using both clinical and FOX programs, a second iteration of FOX optimization was performed. Following this, the assessments were repeated without further acclimatization. RESULTS: FOX prescribed programming modifications in all subjects. Soundfield-aided thresholds were significantly lower for FOX than the clinical program. Group speech scores in noise were not significantly different between the two programs but three individual subjects had improved speech scores with the FOX MAP, two had worse speech scores, and five were the same. CONCLUSION: FOX provided a standardized approach to fitting based on outcome measures rather than comfort alone. The results indicated that for this group of well-fitted patients, FOX improved outcomes in some individuals. There were significant changes, both better and worse, in individual speech perception scores but median scores remained unchanged. Soundfield-aided thresholds were significantly improved for the FOX group.

Sound localization abilities of unilateral hybrid cochlear implant users with bilateral low-frequency hearing.

OBJECTIVE: To assess the sound localization abilities of subjects unilaterally implanted with a hybrid cochlear implant in different sound localization conditions. STUDY DESIGN: A prospective, single-subject repeated measures design was performed to assess the sound localization abilities in 5 different listening conditions: combined (hybrid cochlear implant and contralateral acoustic hearing), bimodal, bilateral acoustic, ipsilateral acoustic, and contralateral acoustic. SETTING: Tertiary referral center. PATIENTS: Eighteen subjects with bilateral low-frequency residual hearing, implanted with a hybrid cochlear implant, were enrolled in this study. MAIN OUTCOME MEASURES: Postoperative sound localization in 5 different listening conditions. RESULTS: Average group results showed a significant improvement in sound localization for all binaural hearing conditions (combined, bimodal, and bilateral acoustic) over monaural conditions (ipsilateral acoustic and contralateral acoustic). Subjects performed significantly better in the combined condition compared with the bimodal and bilateral acoustic conditions when sound was presented from the front and the side of their cochlear implant. CONCLUSION: Best results, for most subjects, were obtained with the routinely used combined fitting. The additional acoustic stimulation of the implanted ear did not significantly improve sound localization. However, a marked improvement has been found by the addition of electrical stimulation, for especially the azimuths ipsilateral and to the front of the cochlear implant, implying the importance of the cochlear implant in sound localization.

Setting and reaching targets with computer-assisted cochlear implant fitting.

OBJECTIVE: The paper aims to demonstrate the feasibility of defining a substantial set of psychoacoustic outcome measures with preset targets and to adopt a systematic methodology for reaching these targets in a large group of subjects, by more than one clinical centre. DESIGN: Retrospective data analysis. SETTING: Multicentre with 14 participating centres. PATIENTS: 255 adults and children using the Advanced Bionics HiRes90k cochlear implant. INTERVENTION: Target driven fitting with the fitting to outcomes expert (FOX) system. MAIN OUTCOME MEASURES: For each patient, 66 measurable psychoacoustical outcomes were recorded several times after cochlear implantation: free field audiometry (6 measures) and speech audiometry (4), spectral discrimination (20), and loudness growth (36), defined from the A§E test battery. These outcomes were reduced to 22 summary variables. The initial results were compared with the latest results. RESULTS: The state of the fitting process could be well monitored by means of the measured variables. The use of the FOX computer assisted CI-programming significantly improved the proportion of the 22 variables on target. When recipients used the automated MAPs provided at switch-on, more than half (57%) of the 22 targets were already achieved before any further optimisation took place. Once the FOX system was applied there was a significant 24% (P < 0.001) increase in the number of targets achieved. CONCLUSIONS: This study demonstrates that it is feasible to set targets and to report on the effectiveness of a fitting strategy in terms of these targets. FOX provides an effective tool for achieving a systematic approach to programming, allowing for better optimisation of recipients' MAPs. The setting of well-defined outcome targets allowed a range of different centres to successfully apply a systematic methodology to monitoring the quality of the programming provided.

Advanced beamformers for cochlear implant users: acute measurement of speech perception in challenging listening conditions.

OBJECTIVE: To investigate the performance of monaural and binaural beamforming technology with an additional noise reduction algorithm, in cochlear implant recipients. METHOD: This experimental study was conducted as a single subject repeated measures design within a large German cochlear implant centre. Twelve experienced users of an Advanced Bionics HiRes90K or CII implant with a Harmony speech processor were enrolled. The cochlear implant processor of each subject was connected to one of two bilaterally placed state-of-the-art hearing aids (Phonak Ambra) providing three alternative directional processing options: an omnidirectional setting, an adaptive monaural beamformer, and a binaural beamformer. A further noise reduction algorithm (ClearVoice) was applied to the signal on the cochlear implant processor itself. The speech signal was presented from 0° and speech shaped noise presented from loudspeakers placed at ±70°, ±135° and 180°. The Oldenburg sentence test was used to determine the signal-to-noise ratio at which subjects scored 50% correct. RESULTS: Both the adaptive and binaural beamformer were significantly better than the omnidirectional condition (5.3 dB±1.2 dB and 7.1 dB±1.6 dB (p<0.001) respectively). The best score was achieved with the binaural beamformer in combination with the ClearVoice noise reduction algorithm, with a significant improvement in SRT of 7.9 dB±2.4 dB (p<0.001) over the omnidirectional alone condition. CONCLUSIONS: The study showed that the binaural beamformer implemented in the Phonak Ambra hearing aid could be used in conjunction with a Harmony speech processor to produce substantial average improvements in SRT of 7.1 dB. The monaural, adaptive beamformer provided an averaged SRT improvement of 5.3 dB.

Perception of polyphony with cochlear implants for 2 and 3 simultaneous pitches.

HYPOTHESIS: It was hypothesized that cochlear implant (CI) subjects would be able to correctly identify 1, 2, and 3 simultaneous pitches through direct electrical stimulation. We further hypothesized that the location on the implant array and the fundamental frequency of the pitches would have an impact on the performance. BACKGROUND: "They gave me back speech but not music" is a sentence commonly heard by CI subjects. One of the reasons is that in music, multiple streams are frequently played at the same time, which is an essential feature of harmony. Current CI speech processors do not allow CI users to perceive such complex polyphonic sounds. METHODS: In the present study, the authors assessed the ability of CI subjects to perceive simultaneous modulation frequencies based on direct electrical stimulation. Ten CI subjects were asked to identify 1, 2, and 3 simultaneous pitches applied on different electrodes using sinusoidal amplitude modulation. All stimuli were loudness balanced before the actual identification task. RESULTS: Subjects were able to identify 1, 2, and 3 simultaneous pitches. The further the distance between the 2 electrodes, the better was the performance in the 2-pitch condition. The distance between the modulation frequencies had a significant effect on the performance in the 2-and 3-pitch condition. CONCLUSION: Subjects are able to identify complex polyphonic stimuli based on the number of active electrodes. The additional polyphonic rate pitch cue improves performance in some conditions.

Everyday listening questionnaire: correlation between subjective hearing and objective performance.

OBJECTIVES: Clinical experience has demonstrated that speech understanding by cochlear implant (CI) recipients has improved over recent years with the development of new technology. The Everyday Listening Questionnaire 2 (ELQ 2) was designed to collect information regarding the challenges faced by CI recipients in everyday listening. The aim of this study was to compare self-assessment of CI users using ELQ 2 with objective speech recognition measures and to compare results between users of older and newer coding strategies. METHODS: During their regular clinical review appointments a group of representative adult CI recipients implanted with the Advanced Bionics implant system were asked to complete the questionnaire. The first 100 patients who agreed to participate in this survey were recruited independent of processor generation and speech coding strategy. Correlations between subjectively scored hearing performance in everyday listening situations and objectively measured speech perception abilities were examined relative to the speech coding strategies used. RESULTS: When subjects were grouped by strategy there were significant differences between users of older 'standard' strategies and users of the newer, currently available strategies (HiRes and HiRes 120), especially in the categories of telephone use and music perception. Significant correlations were found between certain subjective ratings and the objective speech perception data in noise. CONCLUSIONS: There is a good correlation between subjective and objective data. Users of more recent speech coding strategies tend to have fewer problems in difficult hearing situations.

Performance of the Harmony™ behind-the-ear processor with the first generation of Advanced Bionics™ implant systems.

OBJECTIVES: When new cochlear implant (CI) sound processors are being introduced by the manufacturers, usually the newest generation implants benefit first from the new technology in order to release the full potential of the new hardware. Subsequently, for the Advanced Bionics system the Harmony behind-the-ear processor was only compatible to the newer generation implants, i.e. the CII and HiRes90K, at the time of market release. After further development of a new Digital Signal Processing code the Harmony could also support the first implant generation, the 'C1' (Clarion 1.0 and 1.2). This study reports on a field trial with a new sound processor designed to be used with older generation CIs from Advanced Bionics, focussing on ergonomic and performance benefits. METHODS: Speech perception tests (Freiburger monosyllables, HSM sentence tests) were performed at a baseline appointment with the subject's clinical processor, followed by the fitting of the Harmony. After a 1 month take-home period the tests were repeated with the Harmony. Additionally, subjective evaluation through questionnaires and a structured interview were administered after upgrading to the sound processor 'C1 Harmony'. Adult users of Advanced Bionics C1 series CIs (n = 29) participated in this study. RESULTS: The new processor provided superior performance in many, though not all, of the speech recognition measurements. Subjective reports indicated certain practical benefits from the new processor, particularly for previous users of body-worn processors. Overall, 80% of the subjects preferred the new processor. CONCLUSION: The positive outcomes from this trial have resulted in the decision to make the new C1 Harmony processor available to all existing users of the early C1 devices.

New cochlear implant research coding strategy based on the MP3(000™) strategy to reintroduce the virtual channel effect.

CONCLUSION: Results for speech recognition in noise tests when using a new research coding strategy designed to introduce the virtual channel effect provided no advantage over MP3(000™). Although statistically significant smaller just noticeable differences (JNDs) were obtained, the findings for pitch ranking proved to have little clinical impact. OBJECTIVES: The aim of this study was to explore whether modifications to MP3000 by including sequential virtual channel stimulation would lead to further improvements in hearing, particularly for speech recognition in background noise and in competing-talker conditions, and to compare results for pitch perception and melody recognition, as well as informally collect subjective impressions on strategy preference. METHODS: Nine experienced cochlear implant subjects were recruited for the prospective study. Two variants of the experimental strategy were compared to MP3000. The study design was a single-blinded ABCCBA cross-over trial paradigm with 3 weeks of take-home experience for each user condition. RESULTS: Comparing results of pitch-ranking, a significantly reduced JND was identified. No significant effect of coding strategy on speech understanding in noise or competing-talker materials was found. Melody recognition skills were the same under all user conditions.