Comparisons of electrophysiological and psychophysical fitting methods for cochlear implants.

OBJECTIVE: This study compared two different versions of an electrophysiology-based software-guided cochlear implant fitting method with a procedure employing standard clinical software. The two versions used electrically evoked compound action potential (ECAP) thresholds for either five or all twenty-two electrodes to determine sound processor stimulation level profiles. Objective and subjective performance results were compared between software-guided and clinical fittings. DESIGN: Prospective, double-blind, single-subject repeated-measures with permuted ABCA sequences. STUDY SAMPLE: 48 post linguistically deafened adults with ≤15 years of severe-to-profound deafness who were newly unilaterally implanted with a Nucleus device. RESULTS: Speech recognition in noise and quiet was not significantly different between software- guided and standard methods, but there was a visit/learning-effect. However, the 5-electrode method gave scores on the SSQ speech subscale 0.5 points lower than the standard method. Clinicians judged usability for all methods as acceptable, as did subjects for comfort. Analysis of stimulation levels and ECAP thresholds suggested that the 5-electrode method could be refined. CONCLUSIONS: Speech recognition was not inferior using either version of the electrophysiology-based software-guided fitting method compared with the standard method. Subject-reported speech perception was slightly inferior with the five-electrode method. Software-guided methods saved about 10 min of clinician's time versus standard fittings.

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.

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.