Speech Perception Changes in the Acoustically Aided, Nonimplanted Ear after Cochlear Implantation: A Multicenter Study.

In recent years there has been an increasing percentage of cochlear implant (CI) users who have usable residual hearing in the contralateral, nonimplanted ear, typically aided by acoustic amplification. This raises the issue of the extent to which the signal presented through the cochlear implant may influence how listeners process information in the acoustically stimulated ear. This multicenter retrospective study examined pre- to postoperative changes in speech perception in the nonimplanted ear, the implanted ear, and both together.

Hearing Preservation Outcomes for 139 Cochlear Implant Recipients Using a Thin Straight Electrode Array.

Objective: To assess the hearing preservation outcomes in a large group of adult cochlear implant recipients implanted with a thin straight electrode array using atraumatic surgical techniques. Factors affecting hearing preservation will be investigated.

Study Design: Prospective cohort study undertaken at the Royal Victorian Eye and Ear Hospital in Melbourne, Australia from December 2010 to May 2015.

Outcomes After Cochlear Implantation in the Very Elderly.

Objective: To evaluate the outcomes after cochlear implantation (CI) in the elderly population, with a particular emphasis on perioperative complications, dizziness, and speech perception outcomes.

Study Design: A retrospective cohort study of elderly cochlear implant patients.

Setting: Tertiary referral center (Cochlear Implant Clinic, Royal Victorian Eye and Ear Hospital, Melbourne).

Comprehensive analysis of cochlear implant failure: usefulness of clinical symptom-based algorithm combined with in situ integrity testing.

Objective: Accurate diagnosis of cochlear implant failures is important for management; however, appropriate strategies to assess possible device failures are not always clear. The purpose of this study is to understand correlation between causes of device failure and the presenting clinical symptoms as well as results of in situ integrity testing and to propose effective strategies for diagnosis of device failure.

Study Design: Retrospective case review.

Deconvolution of overlapping cortical auditory evoked potentials recorded using short stimulus onset-asynchrony ranges.

Objective: The first aim of this study is to validate the theoretical framework of least-squares (LS) deconvolution on experimental data. The second is to investigate the waveform morphology of the cortical auditory evoked potential (CAEP) for five stimulus onset-asynchronies (SOAs) and effects of alternating stimulus frequency in normally hearing adults.

Methods: Eleven adults (19-55 years) with normal hearing were investigated using tone-burst stimuli of 500 and 2000 Hz with SOAs jittered around 150, 250, 450, and 850 ms in a paired-interval paradigm with fixed or alternating stimulus frequency.

Poly-vinyl-alcohol (PVA) coating of cochlear implant electrode arrays: an in-vivo biosafety study.

Objective: The tissue response and biosafety of poly-vinyl-alcohol (PVA) has been investigated to explore its potential use as an agent to straighten pre-curved cochlear implant electrode arrays for surgical insertion.

Methods: Test arrays were implanted either subcutaneously or into the cochlea of guinea pigs for 3 months. The arrays were uncoated (Treatment 1) or coated with low molecular weight (MW) PVA (Treatment 2), high MW PVA (Treatment 3) or a 50:50 mixture of low and high MW PVA (Treatment 4).

Assessing children with profound hearing loss and severe language delay: getting a broader picture.

Six children with profound hearing loss and severe language delay participated in this pilot study. Four of the children used a Nucleus multi-channel cochlear implant only, while two wore binaural hearing aids. All the children had been diagnosed at an early age, fitted with a sensory device soon after, had considerable device experience and had attended an auditory oral early intervention setting.

Initial clinical experience with a totally implantable cochlear implant research device.

Objective: To evaluate the effectiveness and issues associated with a research totally implantable cochlear implant (TIKI).

Study Design: Limited patient trial.

Setting: Tertiary referral center.

Effects of steroids and lubricants on electrical impedance and tissue response following cochlear implantation.

The present study examined the effects of steroids and lubricants on electrical impedance and tissue response following cochlear implantation in animal models. Guinea pigs were implanted following either no treatment, or intrascalar injection with dexamethasone, triamcinolone, sodium hyaluronate or saline. Cats were implanted following either no treatment, or intrascalar injection with dexamethasone, triamcinolone or a mixture of triamcinolone with sodium hyaluronate.

Psychophysical measures in patients fitted with Contour and straight Nucleus electrode arrays.

The objective of this study was to compare the psychophysical performance of patients using the Nucleus Contour electrode array with that of patients using the straight banded-electrode array. In particular, we wished to consider how psychophysical parameters would differ for an electrode array positioned closer to the modiolus, and how this might influence both patient benefits and the design of speech processing strategies. Nine subjects participated in the study: four used the Nucleus straight array and five used the Nucleus Contour electrode array.

Spatial spread of neural excitation: comparison of compound action potential and forward-masking data in cochlear implant recipients.

The feasibility of using the electrically evoked compound action potential (ECAP), measured with the NRT system (Neural Response Telemetry) and the NRT software (version 2.04), to quantify the longitudinal spread of neural excitation was examined in four subjects fitted with the Nucleus C124M cochlear implant. The ECAP and psychophysical forward-masking profiles were measured using stimulation on each of three electrodes, in basal, middle and apical positions.

A study of intra-cochlear electrodes and tissue interface by electrochemical impedance methods in vivo.

This paper presents methods, results and analysis for measurements of the electrochemical impedance of platinum electrodes (approximately 0.43 mm2) over a 6-month implantation in the cat cochlea. The study aimed to improve our understanding of the effects of tissue response on impedance behaviour.

Spatial spread of neural excitation in cochlear implant recipients: comparison of improved ECAP method and psychophysical forward masking.

This study introduces and evaluates a method for measurement of the longitudinal spread of electrically evoked neural excitation in the cochlea, using the Neural Response Telemetry system (NRT) available with the Nucleus((R)) 24 cochlear implant system. The recently released version of the NRT software (version 3.0) enables presentation of the 'masker' and 'probe' on different electrodes.

Threshold, comfortable level and impedance changes as a function of electrode-modiolar distance.

Objective: The study investigated the hypothesis that threshold and comfortable levels recorded from cochlear implant patients would reduce, and dynamic range increase, as distance of the electrode from the modiolar wall (radial distance) decreases. Two groups of cochlear implant patients participated; one group using the Nucleus' 24 Contour electrode array, and one group using the Nucleus standard straight (banded) array. The Nucleus 24 Contour array has been shown in temporal bone studies to lie closer to the modiolus than the banded array.

The role of radiographic phase-contrast imaging in the development of intracochlear electrode arrays.

Objective: This study describes the application of a new radiographic imaging modality, phase-contrast radiography, to in vitro human temporal bone imaging and investigates its use in the development of new electrode arrays for cochlear implants.

Background: The development of perimodiolar electrode arrays for cochlear implants requires detailed information from postoperative radiologic assessment on the position of the array in relation to the cochlear structures. Current standard radiographic techniques provide only limited details.

Chronic electrical stimulation of the auditory nerve using high surface area (HiQ) platinum electrodes.

High surface area cochlear implant electrodes with much smaller geometric surface areas than current designs might be used in the future to increase the number of stimulating electrodes along the carrier. Potential problems with an increase in charge density for a common stimulus resulting from decreasing the geometric surface area would be reduced by the enlarged real surface area of such electrodes. Electrochemically modified (HiQ) platinum (Pt) electrodes, with a real surface area approximately 75 times greater than the current standard Pt electrodes of the same geometric size, had shown in vitro a low polarization (Z(pol)) and electrode impedance (Z(e)), as well as a low residual direct current (DC).

Psychophysics of a prototype peri-modiolar cochlear implant electrode array.

Psychophysical measurements were performed in three hearing-impaired adult subjects implanted with a CI22 cochlear prosthesis (Cochlear Ltd.) fitted with a developmental peri-modiolar electrode array. The array was manufactured with a curvature approximating that of the inner wall of the scala tympani but, after straightening and insertion, lay on average about half way between the inner and outer walls of the scala.

Preliminary results with the AVR ImpaCt frequency-transposing hearing aid.

Currently, the only behind-the-ear hearing aid that provides a frequency transposition function is the ImpaCt DSR675, recently introduced by AVR Communications Ltd. of Israel. In tests with three hearing-impaired adults, the performance of the ImpaCt aid(s) was compared with that of each subject's own (nontransposing) hearing aids.

Speech perception with steeply sloping hearing loss: effects of frequency transposition.

Six adults with a very steeply sloping high-frequency hearing loss listened to monosyllabic words in several conditions. In the first condition, their ability to identify phonemes with a signal-to-noise ratio of 6 dB was measured. Results were similar to those of normally hearing subjects listening to the same material through low-pass filters having comparable cut-off frequencies.

Preferred listening levels: the effect of background noise for moderate-to-profoundly hearing impaired aid users.

The effects of background noise on the choice of preferred listening level for moderately-to-profoundly hearing impaired adults were investigated. During three listening conditions: 'quiet' (isolated monosyllables), 'suppress' (speech with noise attenuated in the gaps between words), and 'steady' (speech with continuous noise), subjects chose a level that maximized intelligibility without being uncomfortable while listening through a hearing aid. The group mean preferred level for 'suppress' was significantly higher than for 'steady', indicating that the level of noise between words influenced these subjects' choice of listening level.

Improvements in speech perception with use of the AVR TranSonic frequency-transposing hearing aid.

Five adults with sensorineural hearing impairment participated in a trial comparing the performance of the AVR TranSonic frequency-transposing hearing aid with that of their own conventional aids. They used the TranSonic for approximately 12 weeks, during which time systematic changes were made to the transposition parameters. Speech perception was assessed with each setting of those parameters and with the participants' own hearing aids.

Loudness perception and frequency discrimination in subjects with steeply sloping hearing loss: possible correlates of neural plasticity.

Loudness functions and frequency difference limens (DLFs) were measured in five subjects with steeply sloping high-frequency sensorineural hearing loss. The stimuli were pulsed pure tones encompassing a range of frequencies. Loudness data were obtained using a 2AFC matching procedure with a 500-Hz reference presented at a number of levels.

Clinical findings for a group of infants and young children with auditory neuropathy.

Objective: To examine the prevalence of auditory neuropathy in a group of infants at risk for hearing impairment and to present an overview of the clinical findings for affected children.

Design: Results for 20 subjects who showed repeatable cochlear microphonic potentials in the absence of click-evoked auditory brain stem responses are included in this study. Behavioral and steady state evoked potential thresholds were established in each case.

Control of hearing-aid saturated sound pressure level by frequency-shaped output compression limiting.

To fit a hearing aid successfully, it is important to set the Saturated Sound Pressure Level (SSPL) or Maximum Power Output (MPO) appropriately. The SSPL should be low enough to prevent sounds from being amplified to uncomfortable loudness, and yet high enough to maximize speech intelligibility and signal quality. To help attain an optimum SSPL setting, a novel output compression limiting scheme, with shapable MPO (ShaMPO), has been devised.