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.

Facilitation and refractoriness of the electrically evoked compound action potential.

In this study we aim to resolve the contributions of facilitation and refractoriness at very short pulse intervals. Measurements of the refractory properties of the electrically evoked compound action potential (ECAP) of the auditory nerve in cochlear implant (CI) users at inter pulse intervals below 300 μs are influenced by facilitation and recovery effects. ECAPs were recorded using masker pulses with a wide range of current levels relative to the probe pulse levels, for three suprathreshold probe levels and pulse intervals from 13 to 200 μs.

A clinical assessment of cochlear implant recipient performance: implications for individualized map settings in specific environments.

Individual speech intelligibility was measured in quiet and noise for cochlear Implant recipients upgrading from the Freedom to the CP900 series sound processor. The postlingually deafened participants (n = 23) used either Nucleus CI24RE or CI512 cochlear implant, and currently wore a Freedom sound processor. A significant group mean improvement in speech intelligibility was found in quiet (Freiburg monosyllabic words at 50 dB) and in noise (adaptive Oldenburger sentences in noise) for the two CP900 series SmartSound programs compared to the Freedom program.

The Intra-Cochlear Impedance-Matrix (IIM) test for the Nucleus® cochlear implant.

Objective: To describe the principles and operation of a new telemetry-based function test for the Nucleus® cochlear implant, known as the CS19 Intra-Cochlear Impedance Matrix (IIM) and to present results from a multicentre clinical study to establish reproducibility (test-retest reliability) and normative ranges.

Method: The IIM test measures bipolar impedances between all electrode pairs and employs a normalization procedure based on common ground impedances in order to identify abnormal current paths among electrodes. Six European clinics collected IIM data from a total of 192 devices.

Accuracy of measurement in electrically evoked compound action potentials.

Background: Electrically evoked compound action potentials (ECAP) in cochlear implant (CI) patients are characterized by the amplitude of the N1P1 complex. The measurement of evoked potentials yields a combination of the measured signal with various noise components but for ECAP procedures performed in the clinical routine, only the averaged curve is accessible. To date no detailed analysis of error dimension has been published.

Investigation of a matrix sentence test in noise: reproducibility and discrimination function in cochlear implant patients.

Objective: The aim of this study was to describe common properties (reproducibility, discrimination function, and its steepness) of matrix tests used for cochlear implant (CI) users and to obtain data for the German-language version matrix test, the Oldenburg sentence test (OLSA), presented in noise.

Design: The speech reception thresholds (SRT) in noise were measured by means of an adaptive test procedure, and by measurement at various signal-to-noise ratios to determine the course of the entire discrimination function per subject.

Study Sample: The measurements were performed on 38 CI users fitted with a Cochlear(™) Freedom(®) or a Cochlear(™) Nucleus(®) 5 CI system.

Evaluation of Neural Response Telemetry (NRT™) with focus on long-term rate adaptation over a wide range of stimulation rates.

Custom Sound EP™ (CSEP) is an advanced flexible software tool dedicated to recording of electrically evoked compound action potentials (ECAPs) in Nucleus® recipients using Neural Response Telemetry™ (NRT™). European multi-centre studies of the Freedom™ cochlear implant system confirmed that CSEP offers tools to effectively record ECAP thresholds, amplitude growth functions, recovery functions, spread of excitation functions, and rate adaptation functions and an automated algorithm (AutoNRT™) to measure threshold profiles. This paper reports on rate adaptation measurements.

Results of a multicenter clinical study evaluating a new Smart algorithm to measure neural response imaging.

Objective: To evaluate the smart algorithm in speed and reliability of threshold estimation compared with the algorithm available in the standard fitting software and to evaluate the possibility of using programs based on the smart algorithm instead of programs derived from behavioral measures.

Patients: Twenty subjects unilaterally implanted with a CII Bionic Ear or HiRes90K device.

Interventions: Neural response imaging thresholds (tNRI) were measured using both the smart approach within the Research Studies Platform for Objective Measures and the SoundWave fitting software.

Clinical evaluation of cochlear implant sound coding taking into account conjectural masking functions, MP3000™.

Efficacy of the SPEAK and ACE coding strategies was compared with that of a new strategy, MP3000™, by 37 European implant centers including 221 subjects. The SPEAK and ACE strategies are based on selection of 8-10 spectral components with the highest levels, while MP3000 is based on the selection of only 4-6 components, with the highest levels relative to an estimate of the spread of masking. The pulse rate per component was fixed.

Benefits of the HiRes 120 coding strategy combined with the Harmony processor in an adult European multicentre study.

Conclusion: The Harmony processor was found to be reliable, comfortable and offered a substantially increased battery life compared with the previous generation processor. No significant improvement in speech understanding with HiRes was demonstrated from objective measures, but the majority of subjects showed a clear subjective preference for the combination HiRes 120/Harmony processor.

Objectives: To evaluate experience with the Harmony™ sound processor, together with the HiRes 120 strategy.

Speech perception performance as a function of stimulus pulse rate and processing strategy preference for the Cochlear Nucleus CI24RE device: relation to perceptual threshold and loudness comfort profiles.

Current cochlear implants can operate at high pulse rates. The effect of increasing pulse rate on speech performance is not yet clear. Habituation to low rates may affect the outcome.

Auditory feedback does not influence random number generation: Evidence from profoundly deaf adults with cochlear implant.

Oral random number generation is a widely used neuropsychological task engaging a number of overlapping neural systems of attention, number representation, response generation, and working memory. Although phonological processing is known to be essential for random number generation no information exists on the significance of the auditory feedback of hearing one's own voice on task performance. We therefore examined the influence of auditory feedback in 15 profoundly deaf adults with cochlear implants in a device-on/off experiment.

Clinical results of AutoNRT, a completely automatic ECAP recording system for cochlear implants.

Objective: AutoNRT is the completely automatic electrically evoked compound action potential (ECAP) measuring algorithm in the recently released Nucleus Freedom cochlear implant system. AutoNRT allows clinicians to automatically record T-NRT profiles that in turn can be used as a guide for initial fitting. The algorithm consists of a pattern recognition part that judges if the traces contain an ECAP and an intelligent flow that optimizes the measurement parameters and finds the ECAP threshold (T-NRT).

Measuring the refractoriness of the electrically stimulated auditory nerve.

Intracochlear recordings in cochlear implant recipients provide access to the electrically evoked compound action potential (ECAP). ECAP thresholds are potential predictors of speech processor map's threshold and comfortable loudness levels. The auditory nerve's refractory properties can influence these levels due to high-rate stimulation with interpulse intervals within the relative refractory period.

Impact to the head increases cochlear implant reimplantation rate in children.

Objective: To describe the outcome of cochlear implantation in children and to discuss the cause and management of cochlear reimplantation.

Study Design: Retrospective chart review.

Methods: The medical records of 110 patients younger than 18 years of age, who underwent cochlear implantation at the Department of ORL, Head and Neck Surgery, of the University of Kiel, Germany, were reviewed for demographics, complications, and history of revision surgery.

Benefits of bilateral electrical stimulation with the nucleus cochlear implant in adults: 6-month postoperative results.

Objective: To evaluate the benefits of bilateral electrical stimulation for hearing-impaired adult subjects using the Nucleus 24 cochlear implant in a multicenter study, and to compare and quantify performance on speech perception measures in quiet and in noise and localization ability for unilateral and bilateral cochlear implant use.

Design: : Repeated single subject measures were carried out for each subject, with each subject serving as their own control. Assessment of unilateral and bilateral listening conditions for performance on tests of speech comprehension and sound localization were performed.

Measurement of the electrically evoked compound action potential via a neural response telemetry system.

The main aim of this study was to validate a new technique, neural response telemetry (NRT), for measuring the electrically evoked compound action potential in adult cochlear implant users via their Nucleus C124M implant. Thirty-eight adults were evaluated with a variety of measurement procedures with the NRT software. Electrically evoked compound action potentials were obtained in 31 of the 38 adults (81.