Cochlear Limited

About: Cochlear Limited is a company organization based out in Sydney, New South Wales, Australia. It is known for research contribution in the topics: Cochlear implant & Hearing loss. The organization has 1290 authors who have published 1479 publications receiving 33109 citations. The organization is also known as: кохлеарные Americas & COCHLEAR LIMITED.

A MultiCenter Analysis of Factors Associated with Hearing Outcome for 2,735 Adults with Cochlear Implants.

Abstract: While the majority of cochlear implant recipients benefit from the device, it remains difficult to estimate the degree of benefit for a specific patient prior to implantation. Using data from 2,735 cochlear-implant recipients from across three clinics, the largest retrospective study of cochlear-implant outcomes to date, we investigate the association between 21 preoperative factors and speech recognition approximately one year after implantation and explore the consistency of their effects across the three constituent datasets. We provide evidence of 17 statistically significant associations, in either univariate or multivariate analysis, including confirmation of associations for several predictive factors, which have only been examined in prior smaller studies. Despite the large sample size, a multivariate analysis shows that the variance explained by our models remains modest across the datasets (R2=0.12-0.21). Finally, we report a novel statistical interaction indicating that the duration of deafness in the implanted ear has a stronger impact on hearing outcome when considered relative to a candidate's age. Our multicenter study highlights several real-world complexities that impact the clinical translation of predictive factors for cochlear implantation outcome. We suggest several directions to overcome these challenges and further improve our ability to model patient outcomes with increased accuracy.

A uniform graphical representation of intensity coding in current-generation cochlear implant systems.

Abstract: Objectives Understanding and predicting the impact of MAP changes on the electrical current delivered at the level of cochlear implant (CI) electrodes is challenging. However, it is an important prerequisite for effectively programming these devices in clinical practice. This article describes a graphical representation to illustrate the intensity-coding behavior of four CI systems (Cochlear, MED-EL, Advanced Bionics, and Neurelec). Design For this the authors have broken down the intensity coding into two separate transformations: (1) from broadband acoustical input to band limited channel amplitude and (2) the mapping function within a single channel. These functions have been synthesized and presented in a uniform plot across brands. Results The plot describes the output of a CI channel in response to different input signals. This has been incorporated in an interactive software application that illustrates the different stages of intensity coding and the impact of the relevant fitting parameters for each CI brand. Conclusions The plot provides the clinician with an assistive tool to better understand and predict the behavior of CIs, which may lead to more knowledgeable interpretation and CI programming.

Parametric fitting of a cochlear implant

Abstract: A method of fitting an auditory stimulation system to a recipient the system having a plurality of channels, and the method including the steps of establishing an initial current level profile representative of a current level setting spanning across at least some of the plurality of channels and adjusting parameters of the initial current level profile in the presence of a stimulation signal. There is further included a programming apparatus adapted to be interfaced with the auditory stimulation system to allow manipulation of threshold (T) and comfort (C) levels of the system. The apparatus includes a graphical display means adapted to display a graphical representation of the current profile of the channel array and means for adjusting a current level setting of the current profile of the array.

Electrophysiological spread of excitation and pitch perception for dual and single electrodes using the Nucleus Freedom cochlear implant.

Abstract: OBJECTIVES: The first objective of the study was to determine whether there were any consistent differences in the electrophysiological spread of excitation (SOE) function, as measured using the electrically evoked compound action potential (ECAP), between dual and single electrode stimulation with the Nucleus Freedom cochlear implant system. Dual electrode stimulation is produced by electrically coupling two adjacent single electrodes. The second objective was to determine whether there were any relationships between the SOE functions and psychophysically measured pitch ranking of dual and single electrodes. DESIGN: Nine adult cochlear implant subjects participated in the study. ECAPs for dual and single electrode stimulation were measured using the forward masking paradigm, as also used in the Neural Response Telemetry (NRT) software with the Nucleus implant. Research software was used to generate the dual and single electrode stimuli and record the ECAPs. Spread of excitations (SOEs) were measured on a dual electrode and the two adjacent single electrodes, at three positions on the array: apical, mid, and basal. Compared were the ECAP amplitudes at the peak of the SOE functions, the widths of the scaled SOE functions at the 75% point, and the electrode positions at the peak of the SOE function and at the 75%, 50%, and 25% points on apical and basal sides of the scaled functions. Pitch ranking was measured for the same sets of dual and single electrodes. A two-alternative forced choice procedure was used, with the electrodes in each set paired with each other as AB and BA pairs. The subject indicated which of the two stimuli had the higher pitch. RESULTS: Dual electrode SOEs could be successfully obtained using the same methods as used to measure single electrode SOEs. The shapes of the dual and single electrodes SOEs were similar. There was a trend of a higher ECAP amplitude for the dual electrode at the peak of the SOE function, but this was only significant for two comparisons at the apical and basal positions. There were no significant differences in the SOE widths between dual and single electrodes. The electrodes at the peak of the SOE function and on the apical and basal sides of the function at the 75% position were, in most cases, tonotopically ordered. At the 50% and 25% positions, there were fewer significant differences between the dual and single electrodes The pitch ranking results showed that in 74% of cases, the single and dual electrodes at each position were successfully ranked in the expected tonotopic order. There were no statistically significant correlations between the pitch ranking results and the ordering of electrodes on the SOE functions. CONCLUSIONS: Dual electrode stimulation produced similar SOE functions as single electrode stimulation. A tonotopic ordering of electrodes at the peak of the SOE and on the sides of the functions was found, but this was not statistically related to the pitch ranking results. SUMMARY: Electrophysiological spread of neural excitation (SOE) and pitch perception using dual and single electrodes was investigated in nine subjects using the Nucleus Freedom cochlear implant. Dual electrodes are produced by electrically coupling two adjacent single electrodes. The dual and single electrodes SOEs were similar in shape. Higher electrophysiological response amplitudes were generally found for the dual electrodes. There were no differences in SOE widths between dual and single electrodes. In three quarters of cases, dual and single electrodes were successfully pitch ranked in the expected tonotopic order. No significant relationships between pitch ranking and the SOE functions were found.

Speech enhancement based on neural networks applied to cochlear implant coding strategies

Abstract: Traditionally, algorithms that attempt to significantly improve speech intelligibility in noise for cochlear implant (CI) users have met with limited success, particularly in the presence of a fluctuating masker. In the present study, a speech enhancement algorithm integrating an artificial neural network (NN) into CI coding strategies is proposed. The algorithm decomposes the noisy input signal into time-frequency units, extracts a set of auditory-inspired features and feeds them to the NN to produce an estimation of which CI channels contain more perceptually important information (higher signal-to-noise ratio, SNR). This estimate is then used accordingly to retain a subset of channels for electrical stimulation, as in traditional n-of-m coding strategies. The proposed algorithm was tested with 10 normal-hearing participants listening to CI noise-vocoder simulations against a conventional Wiener filter based enhancement algorithm. Significant improvements in speech intelligibility in stationary and fluctuating noise were found over both unprocessed and Wiener filter processed conditions.