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Dive into the research topics where Matthijs Killian is active.

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Featured researches published by Matthijs Killian.


Audiology and Neuro-otology | 2006

Measuring the Refractoriness of the Electrically Stimulated Auditory Nerve

Andre Morsnowski; Basile Charasse; Lionel Collet; Matthijs Killian; Joachim Müller-Deile

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. Recovery functions were investigated at 84 stimulation sites in 14 Nucleus CI24 recipients using neural response telemetry and a modified forward masking technique. This technique introduces a reference masker-probe interval (MPI). In our study, an appropriate value between 300 and 375 µs was determined for this reference MPI, and the use of a reference MPI of 300 µs is suggested for recovery and amplitude growth functions. A median absolute refractory period of about 390 µs and a median time constant of about 425 µs were obtained by fitting an exponential model to the data. Hence, the auditory nerve is usually in relative refractory state when standard neural response telemetry forward masking is selected because of its default MPI of 500 µs. This can bias the measurement of ECAP thresholds. Additionally, the shape of standard forward masking recovery functions was explained by the influence of latency shift of the neural response.


Ear and Hearing | 2007

Performance and preference for ACE stimulation rates obtained with nucleus RP 8 and freedom system.

Benno P. Weber; Wai Kong Lai; Norbert Dillier; E L. von Wallenberg; Matthijs Killian; Joerg Pesch; Rolf-Dieter Battmer; Thomas Lenarz

Cochlear recently released the Nucleus® Freedom™ System which has been based on the Nucleus® Research Platform 8. Both systems make use of the same implant, the CI24RE, which includes expanded total stimulation rates up to 32 kHz. In this study the performance of the ACE strategy at 500, 1200 and 3500 pps/channel was investigated using an ABC-CBA design. At the end of each period speech tests were performed. In the CBA phase the patients completed a comparative questionnaire to determine the subjective rate preference. Preliminary results in 13 recipients indicate no differences in for the ACE strategy at rates ranging from 500 pps to 3500 pps/channel.


Audiology and Neuro-otology | 2015

Cochlear Implants as a Treatment Option for Unilateral Hearing Loss, Severe Tinnitus and Hyperacusis

Ángel Ramos Macías; Juan Carlos Falcón González; Manuel Manrique; Constantino Morera; Luis García-Ibáñez; Carlos Cenjor; Chrystellel Coudert-Koall; Matthijs Killian

Tinnitus is an incapacitating condition commonly affecting cochlear implant (CI) candidates. The aim of this clinical study is to assess the long-term effects of CI treatment in patients with severe-to-profound, sensorineural, unilateral hearing loss (UHL) and incapacitating tinnitus. We performed a prospective Cochlear™ company-sponsored multicentre study in five Spanish centres. Sixteen patients with UHL and incapacitating tinnitus, which was indicated by a Tinnitus Handicap Inventory (THI) score >58%, received a Nucleus® CI in their deaf ear. The study design includes repeated within-subject measures on hearing, tinnitus, hyperacusis and quality of life up to 12 months after initial CI fitting. In addition to hearing loss and tinnitus, all patients suffered from hyperacusis. Most patients had a sudden hearing loss and received a CI within 2 years after their hearing loss. Preliminary 6-month, post-CI activation data of 13 subjects showed that the majority of patients perceived a subjective benefit from CI treatment, which was assessed using the THI, a Visual Analogue Scale of tinnitus loudness/annoyance and the Speech, Spatial and Qualities of Hearing Scale. Preliminary 12-month data of 7 subjects showed that most patients also perceived a degree of relief from their hyperacusis. One patient showed no improvements in any of the applied scales, which could be explained by partial insertion of the electrode due to obstruction of the cochlea by otosclerosis. In conclusion, CI can successfully be used in the treatment of UHL patients with accompanying severe tinnitus and hyperacusis. Implantation resulted in hearing benefits and a durable relief from tinnitus and hyperacusis in the majority of patients. These findings support the hypothesis that pathophysiological mechanisms after peripheral sensorineural hearing loss are at least partly reversible when hearing is restored with a CI.


Cochlear Implants International | 2011

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

Andreas Buechner; Andy Beynon; Witold Szyfter; Kazimierz Niemczyk; Ulrich Hoppe; Matthias Hey; J.P.L. Brokx; Julie Eyles; Paul Van de Heyning; Gaetano Paludetti; Andrzej Zarowski; Nicola Quaranta; Thomas Wesarg; Joost M. Festen; Heidi Olze; Ingeborg Dhooge; Joachim Müller-Deile; Ángel Ramos; Stephane Roman; Jean-Pierre Piron; Domenico Cuda; Sandro Burdo; Wilko Grolman; Samantha Roux Vaillard; Alicia Huarte; Bruno Frachet; Constantine Morera; Luis García-Ibáñez; Daniel Abels; Martin Walger

Abstract 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. No significant difference was found for the speech scores and for coding preference between the SPEAK/ACE and MP3000 strategies. Battery life was 24% longer for the MP3000 strategy. With MP3000 the best results were found for a selection of six components. In addition, the best results were found for a masking function with a low-frequency slope of 50 dB/Bark and a high-frequency slope of 37 dB/Bark (50/37) as compared to the other combinations examined of 40/30 and 20/15 dB/Bark. The best results found for the steepest slopes do not seem to agree with current estimates of the spread of masking in electrical stimulation. Future research might reveal if performance with respect to SPEAK/ACE can be enhanced by increasing the number of channels in MP3000 beyond 4–6 and it should shed more light on the optimum steepness of the slopes of the masking functions applied in MP3000.


International Journal of Audiology | 2010

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.

Rolf-Dieter Battmer; Norbert Dillier; Wai Kong Lai; Klaus Begall; Elisabeth Estrada Leypon; Juan Carlos Falcon Gonzalez; Manuel Manrique; Constantino Morera; Joachim Müller-Deile; Thomas Wesarg; Andrzej Zarowski; Matthijs Killian; Ernst Von Wallenberg; Guido F. Smoorenburg

Abstract 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. This paper presents the results of three subsequent studies using different experimental paradigms, applying the Nucleus CI24RE device, and conducted by ten European implant teams. Pulse rate per channel varied from 500 to 3500 pulses per second with ACE and from 1200 to 3500 pps with CIS strategy. The results showed that the first rate presented had little effect on the finally preferred rate. Lower rates were preferred. The effect of pulse rate on word scores of post-linguistic implantees was small; high rates tended to give lower scores. However, there were no significant differences between the word scores across subjects if collected at the individually preferred pulse rate. High pulse rates were preferred when the post-implantation threshold was low. Sumario Los implantes cocleares actuales puede operara a tasas de pulso altas. El efecto de la tasa de pulso en aumento sobre el desempeño en el lenguaje aún no es claro. La habituación a tasas bajas puede afectar el resultado. Este trabajo presenta los resultados de tres estudios subsiguientes que usaron diferentes paradigmas experimentales, utilizando el dispositivo Nucleus CI24RE, y llevado a cabo por diez equipos europeos de implante. La tasa de pulso por canal varió entre 500 a 3500 pulsos por segundo con la estrategia ACE y de 1200 a 3500 pps con la estrategia CIS. Los resultados mostraron que la primera tasa presentada tenía poco efecto sobre la tasa preferida final. Se prefirieron tasas más bajas. El efecto de la tasa de pulso sobre los puntajes de reconocimiento de palabras en implantados post-lingüísticos fue pequeño; tasas más altas tendieron a dar puntajes más bajos. Sin embargo, no existieron diferencias significativas entre los puntajes de reconocimiento de palabras en los diferentes sujetos si se recogían a la tasa preferida individual de pulso. Se prefirieron tasas de pulso más altas cuando el umbral post-implantación era bajo.


International Journal of Audiology | 2009

TNRT profiles with the Nucleus Research Platform 8 system

Waikong Lai; Norbert Dillier; B.P. Weber; Thomas Lenarz; R. Battmer; Bruce J. Gantz; Carolyn J. Brown; Noel L. Cohen; Susan B. Waltzman; Margaret W. Skinner; Laura K. Holden; Robert Cowan; P. A. Busby; Matthijs Killian

This study investigates the effect of the Nucleus CI24RE implants neural response telemetry (NRT) system, which has less internal noise compared to its predecessor, the CI24M/R implant, on the NRT threshold (TNRT) profile across the array. CI24M/R measurements were simulated by ignoring CI24RE measurements with response amplitudes below 50 uV. Comparisons of the estimated TNRTs from the CI24RE measurements and the CI24M/R simulations suggest that, apart from a constant level difference, the TNRT profiles from the newer implant generally would not have differed very much from those of its predecessor. This view was also reflected by principal component analysis (PCA) results which revealed a ‘shift’ component similar to that reported by Smoorenburg et al (2002). On the whole, there is no indication that current practices of using the TNRT profiles for assisting with speech processor programming need to be revised for the CI24RE implant.


Cochlear Implants International | 2015

Conversion of adult Nucleus® 5 cochlear implant users to the Nucleus® 6 system

Geert De Ceulaer; Freya Swinnen; David Pascoal; Birgit Philips; Matthijs Killian; Chris James; Paul J. Govaerts; Ingeborg Dhooge

Abstract Objectives Cochlears new sound processor system (Nucleus® 6) features a new noise reduction algorithm called SNR-NR (signal-to-noise ratio), and an environmental classifier called SCAN, which activates the appropriate sound coding algorithms for a given listening environment. In addition, the sound processors (CP910 and CP920) have a data logging feature with data visually summarized using clinical programing software and come with two remote controls, CR210 and CR230. The objective of this clinical study was to conduct a field acceptance study comparing the user experience with the Nucleus® 6 to the Nucleus® 5 system and to evaluate the benefits of Nucleus® 6 in an adult population currently equipped with the previous generation Nucleus® 5 sound processor. Our primary objective was to compare speech recognition in speech-weighted noise using Nucleus® 6 with SCAN (activating SNR-NR) with the default Nucleus® 5 ‘Noise’ Program. Secondary objectives included comparisons of speech recognition in quiet, subjective performance feedback via questionnaires and diaries, and recipient preference for device and program type. Methods A prospective controlled trial was conducted with 30 adult Nucleus CI recipients using the Nucleus® 5 sound processor (condition A). The Nucleus® 6 sound processor (condition B) was evaluated in a within-subject ABBA design, with repeated speech in noise (S0N0, LIST sentence test), and speech in quiet testing (S0, NVA words). The remote controls were randomly given during the two B intervals. In addition, recipients had to complete questionnaires and diaries on the use of their current as well as new sound processors and remotes. Results The group mean speech reception threshold in noise (SRT50) with Nucleus® 6 SCAN was significantly better (1.2 dB SNR) than with the Nucleus® 5 ‘Noise’ Program. Mean speech recognition scores in quiet were not significantly different between the processors. Subjective performance feedback (APHAB) did not show a significant difference between Nucleus® 6 and Nucleus® 5 with high satisfaction scores being reported for both sound processors. Recipients preferred the SCAN program in noise and reported a clear overall preference for the Nucleus® 6 system. Clinicians were satisfied with the conversion process from Nucleus® 5 to Nucleus® 6. Discussion and conclusion SNR-NR provides a significant benefit in noise. Recipients were easily converted from Nucleus® 5 to Nucleus® 6 requiring little or no sound quality adjustment period. The Nucleus® 6 SCAN program was well accepted by the majority of recipients for use during their daily life.


American Journal of Audiology | 2015

A Series of Case Studies of Tinnitus Suppression With Mixed Background Stimuli in a Cochlear Implant

Richard S. Tyler; Andrew J. Keiner; Kurt Walker; Aniruddha K. Deshpande; Shelley Witt; Matthijs Killian; Helena Ji; Jim Patrick; Norbert Dillier; Pim van Dijk; Wai Kong Lai; Marlan R. Hansen; Bruce J. Gantz

PURPOSE Background sounds provided by a wearable sound playback device were mixed with the acoustical input picked up by a cochlear implant speech processor in an attempt to suppress tinnitus. METHOD First, patients were allowed to listen to several sounds and to select up to 4 sounds that they thought might be effective. These stimuli were programmed to loop continuously in the wearable playback device. Second, subjects were instructed to use 1 background sound each day on the wearable device, and they sequenced the selected background sounds during a 28-day trial. Patients were instructed to go to a website at the end of each day and rate the loudness and annoyance of the tinnitus as well as the acceptability of the background sound. Patients completed the Tinnitus Primary Function Questionnaire (Tyler, Stocking, Secor, & Slattery, 2014) at the beginning of the trial. RESULTS Results indicated that background sounds were very effective at suppressing tinnitus. There was considerable variability in sounds preferred by the subjects. CONCLUSION The study shows that a background sound mixed with the microphone input can be effective for suppressing tinnitus during daily use of the sound processor in selected cochlear implant users.


<p>Journal of Physics: Conference Series [ISSN:1742-6588], vol. 689 (1)</p> | 2016

A Psychophysics experimental software to evaluate electrical pitch discrimination in Nucleus cochlear implanted patients

M.T. Pérez Zaballos; Á. Ramos de Miguel; Matthijs Killian; Á. Ramos Macías

Multichannel electrode array design in cochlear implants has evolved into two major categories: straight and perimodiolar electrodes. When implanted, the former lies along the outer wall of the scala tympani, while the later are located closer to the modiolus, where the neural ends are. Therefore, a perimodiolar position of the electrode array could be expected to result in reduced stimulus thresholds and stimulating currents, increased dynamic range, and more localized stimulation of the neural elements. However, their advantage for pitch discrimination has not been conclusively stated. Therefore, in order to study electrode independence, a psychophysical software has been developed, making use of Nucleus Implant Communicator tools provided by Cochlear company under a research agreement. The application comprises a graphical interface to facilitate its use, since previous software has always required some type of computer language skills. It allows for customization of electrical pulse parameters, measurement of threshold and comfort levels, loudness balancing and alternative forced choice experiments to determine electrode discrimination in Nucleus© users.


Cochlear Implants International | 2014

Evaluation of neural response telemetry (NRT™) with focus on long-term rate adaptation over a wide range of stimulation rates

Alicia Huarte; Ángel Ramos; Constantino Morera; Luis García-Ibáñez; Rolf D. Battmer; Norbert Dillier; Thomas Wesarg; Joachim Müller-Deile; Mattias Hey; Erwin Offeciers; Ernst Von Wallenberg; Chrystelle Coudert; Matthijs Killian

Abstract 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. Rate adaptation of ECAP amplitudes can successfully be measured up to rates of 495 pulses per second (pps) by repeating conventional ECAP measurements and over a wide range of rates up to 8000 pps using the masked response extraction technique. Rate adaptation did not show a predictable relationship with speech perception and coding strategy channel rate preference. The masked response extraction method offers opportunities to study long-term rate adaptation with well-defined and controlled stimulation paradigms.

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Basile Charasse

Centre national de la recherche scientifique

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Chris James

University of Melbourne

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Ingeborg Dhooge

Ghent University Hospital

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