Time filter

Source Type

Lenarz T.,Hannover Medical School | Verhaert N.,University Hospitals Leuven | Verhaert N.,Catholic University of Leuven | Desloovere C.,University Hospitals Leuven | And 11 more authors.
Audiology and Neurotology | Year: 2014

The aim of this study was to investigate the efficacy of a direct acoustic cochlear implant (DACI) for speech understanding in noise in patients suffering from severe to profound mixed hearing loss (MHL) due to various etiologies compared to the preoperative best-aided condition. The study was performed at five tertiary referral centers in Europe (Belgium, Germany, Poland and Spain). Nineteen adult subjects with severe to profound MHL due to (advanced) otosclerosis, ear canal fibrosis, chronic otitis media, tympanosclerosis or previous cholesteatoma were implanted with a DACI (Codacs™ Investigational Device) combined with a conventional stapes prosthesis. Unaided and aided speech reception scores in quiet and in noise, preoperative and postoperative air and bone conduction thresholds and aided and unaided sound field thresholds were measured prospectively during the study. Subjective benefit analysis was determined through the Abbreviated Profile of Hearing Aid Benefit questionnaire. Quality of life was measured by the Health Utilities Index. All subjects were fitted preoperatively with hearing aids and/or a bone conduction implant on a headband before DACI implantation. This allows direct comparison between different hearing rehabilitation solutions. The mean speech reception threshold in noise improved significantly by 7.9 dB signal-to-noise ratio (SNR) after activation of the DACI compared to the preoperative best-aided condition. For all 19 subjects, a mean postoperative aided speech reception threshold of 2.6 dB SNR (standard deviation: 8.3 dB) was measured. On average, no significant shift in the bone conduction thresholds was noted 4-5 months after implantation. A mean sound field threshold improvement of 46 and 16 dB was measured compared to the preoperative unaided and best-aided condition, respectively. Speech perception tests in quiet showed a mean improvement of the word recognition scores by 65 and 48% at 65 dB SPL compared to the preoperative unaided and best-aided condition, respectively. In summary, DACI provides an effective improvement of the speech perception in noise compared to the best-aided condition in subjects suffering from severe to profound MHL. © 2014 S. Karger AG, Basel.


Qazi O.U.R.,Cochlear Technology Center Belgium | Qazi O.U.R.,Catholic University of Leuven | Van Dijk B.,Cochlear Technology Center Belgium | Moonen M.,Catholic University of Leuven | Wouters J.,Catholic University of Leuven
IEEE Transactions on Biomedical Engineering | Year: 2012

Cochlear implant (CI) recipients report severe degradation of speech understanding under noisy conditions. Most CI recipients typically can require about 10-25 dB higher signal-to-noise ratio than normal hearing (NH) listeners in order to achieve similar speech understanding performance. In recent years, significant emphasis has been put on binaural algorithms, which not only make use of the head shadow effect, but also have two or more microphone signals at their disposal to generate binaural inputs. Most of the CI recipients today are unilaterally implanted but they can still benefit from the binaural processing utilizing a contralateral microphone. The phase error filtering (PEF) algorithm tries to minimize the phase error variance utilizing a time-frequency mask for noise reduction. Potential improvement in speech intelligibility offered by the algorithm is evaluated with four different kinds of mask functions. The study reveals that the PEF algorithm which uses a contralateral microphone but unilateral presentation provides considerable improvement in intelligibility for both NH and CI subjects. Further, preference rating test suggests that CI subjects can tolerate higher levels of distortions than NH subjects, and therefore, more aggressive noise reduction for CI recipients is possible. © 1964-2012 IEEE.


Buyens W.,Cochlear Technology Center Belgium | Buyens W.,Catholic University of Leuven | Van Dijk B.,Cochlear Technology Center Belgium | Wouters J.,Catholic University of Leuven | Moonen M.,Catholic University of Leuven
European Signal Processing Conference | Year: 2013

Music perception and appreciation remain generally poor in cochlear implant (CI) users. Simple musical structures, a clear rhythm/beat and lyrics that are easy to follow are among the top factors to enhance music appreciation. A music pre-processing scheme for CI users is described in which vocals and percussion are elucidated using harmonic/percussive sound separation. The scheme is capable of modifying relative instrument level settings for improving music appreciation in CI users. The scheme is assessed with normal hearing subjects (N=5) using a pairwise comparison analysis and CI simulated music excerpts. All test subjects except one significantly preferred the music excerpts from the music pre-processing scheme. © 2013 EURASIP.


Buyens W.,Cochlear Technology Center Belgium | Buyens W.,Catholic University of Leuven | Van Dijk B.,Cochlear Technology Center Belgium | Wouters J.,Catholic University of Leuven | Moonen M.,Catholic University of Leuven
IEEE Transactions on Biomedical Engineering | Year: 2015

Objective: Listening to music is still one of the more challenging aspects of using a cochlear implant (CI) for most users. Simple musical structures, a clear rhythm/beat, and lyrics that are easy to follow are among the top factors contributing to music appreciation for CI users. Modifying the audio mix of complex music potentially improves music enjoyment in CI users. Methods: A stereo music preprocessing scheme is described in which vocals, drums, and bass are emphasized based on the representation of the harmonic and the percussive components in the input spectrogram, combined with the spatial allocation of instruments in typical stereo recordings. The scheme is assessed with postlingually deafened CI subjects (N = 7) using pop/rock music excerpts with different complexity levels. Results: The scheme is capable of modifying relative instrument level settings, with the aim of improving music appreciation in CI users, and allows individual preference adjustments. The assessment with CI subjects confirms the preference for more emphasis on vocals, drums, and bass as offered by the preprocessing scheme, especially for songs with higher complexity. Conclusion: The stereo music preprocessing scheme has the potential to improve music enjoyment in CI users by modifying the audio mix in widespread (stereo) music recordings. Significance: Since music enjoyment in CI users is generally poor, this scheme can assist the music listening experience of CI users as a training or rehabilitation tool. © 2015 IEEE.


Lenarz T.,Hannover Medical School | Zwartenkot J.W.,Radboud University Nijmegen | Stieger C.,University of Bern | Schwab B.,Hannover Medical School | And 6 more authors.
Otology and Neurotology | Year: 2013

Objective: To confirm the clinical efficacy and safety of a direct acoustic cochlear implant. Study Design: Prospective multicenter study. Setting: The study was performed at 3 university hospitals in Europe (Germany, The Netherlands, and Switzerland). Patients: Fifteen patients with severe-to-profound mixed hearing loss because of otosclerosis or previous failed stapes surgery. Intervention: Implantation with a Codacs direct acoustic cochlear implant investigational device (ID) combined with a stapedotomy with a conventional stapes prosthesis Main Outcome Measures: Preoperative and postoperative (3 months after activation of the investigational direct acoustic cochlear implant) audiometric evaluation measuring conventional pure tone and speech audiometry, tympanometry, aided thresholds in sound field and hearing difficulty by the Abbreviated Profile of Hearing Aid Benefit questionnaire. Results: The preoperative and postoperative air and bone conduction thresholds did not change significantly by the implantation with the investigational Direct Acoustic Cochlear Implant. The mean sound field thresholds (0.25-8 kHz) improved significantly by 48 dB. The word recognition scores (WRS) at 50, 65, and 80 dB SPL improved significantly by 30.4%, 75%, and 78.2%, respectively, after implantation with the investigational direct acoustic cochlear implant compared with the preoperative unaided condition. The difficulty in hearing, measured by the Abbreviated Profile of Hearing Aid Benefit, decreased by 27% after implantation with the investigational direct acoustic cochlear implant. Conclusion: Patients with moderate-to-severe mixed hearing loss because of otosclerosis can benefit substantially using the Codacs investigational device. © 2013, Otology & Neurotology, Inc.


Verhaert N.,Catholic University of Leuven | Verhaert N.,University Hospitals Leuven | Walraevens J.,Cochlear Technology Center Belgium | Desloovere C.,University Hospitals Leuven | And 2 more authors.
PLoS ONE | Year: 2016

Severe to profound mixed hearing loss is associated with hearing rehabilitation difficulties. Recently, promising results for speech understanding were obtained with a direct acoustic cochlear implant (DACI). The surgical implantation of a DACI with standard coupling through a stapedotomy can however be regarded as challenging. Therefore, in this experimental study, the feasibility of direct acoustic stimulation was investigated at an anatomically and surgically more accessible inner ear site. DACI stimulation of the intact, blue-lined and opened lateral semicircular canal (LC) was investigated and compared with standard oval window (OW) coupling. Additionally, stapes footplate fixation was induced. Round window (RW) velocity, as a measure of the performance of the device and its coupling efficiency, was determined in fresh-frozen human cadaver heads. Using single point laser Doppler vibrometry, RW velocity could reliably be measured in low and middle frequency range, and equivalent sound pressure level (LE) output was calculated. Results for the different conditions obtained in five heads were analyzed in subsequent frequency ranges. Comparing the difference in RW membrane velocity showed higher LE in the LC opened condition [mean: 103 equivalent dB SPL], than in LC intact or blue-lined conditions [63 and 74 equivalent dB SPL, respectively]. No difference was observed between the LC opened and the standard OW condition. Inducing stapes fixation, however, led to a difference in the low frequency range of LE compared to LC opened. In conclusion, this feasibility study showed promising results for direct acoustic stimulation at this specific anatomically and surgically more accessible inner ear site. Future studies are needed to address the impact of LC stimulation on cochlear micromechanics and on the vestibular system like dizziness and risks of hearing loss. © 2016 Verhaert et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Theelen-Van Den Hoek F.L.,Academic Medical Center Amsterdam | Boymans M.,Academic Medical Center Amsterdam | Stainsby T.,Cochlear Technology Center Belgium | Dreschler W.A.,Academic Medical Center Amsterdam
International Journal of Audiology | Year: 2014

Objective: In categorical loudness scaling (CLS), subjects rate the perceived loudness on a categorical scale with alternatives. ISO 16832 describes an internationally standardized CLS procedure for the acoustical domain. This study focuses on the reproducibility of CLS following the recommendations of ISO 16832 using electrical stimuli presented to cochlear implant (CI) users. Design: Repeated CLS measurements were done using single-electrode stimuli at four electrode positions. Loudness growth functions (LGFs) described loudness as a function of level (μA). LGF shapes were characterized with an exponential b parameter. The reproducibility of the b parameter and inter-session intra-subject differences in percentage dynamic range (DR) between 'Very Soft' and 'Loud-Very Loud' levels were analysed. Study sample: Ten CI users. Results: Inter-session differences did not significantly differ between loudness categories or electrode positions. Across loudness categories the standard deviation of inter-session differences equalled 7.2%DR. The reproducibility of LGF shapes was moderate (r = 0.63). The LGFs of 43% of the measured electrodes significantly deviated from linear (nonzero b parameter). Conclusions: The reproducibility was comparable to the reproducibility for acoustical stimulation in normal-hearing and hearing-impaired listeners. CLS data for electrical stimuli are preferably fitted with a model that is flexible in describing LGF shapes. © 2014 British Society of Audiology, International Society of Audiology, and Nordic Audiological Society.


Buyens W.,Cochlear Technology Center Belgium | Buyens W.,Catholic University of Leuven | Van Dijk B.,Cochlear Technology Center Belgium | Moonen M.,Catholic University of Leuven | Wouters J.,Catholic University of Leuven
International Journal of Audiology | Year: 2014

Objective: Music perception and appraisal are generally poor in cochlear implant recipients. Simple musical structures, lyrics that are easy to follow, and clear rhythm/beat have been reported among the top factors to enhance music enjoyment. The present study investigated the preference for modified relative instrument levels in music with normal-hearing and cochlear implant subjects. Design: In experiment 1, test subjects were given a mixing console and multi-track recordings to determine their most enjoyable audio mix. In experiment 2, a preference rating experiment based on the preferred relative level settings in experiment 1 was performed. Study sample: Experiment 1 was performed with four postlingually deafened cochlear implant subjects, experiment 2 with ten normal-hearing and ten cochlear implant subjects. Results: A significant difference in preference rating was found between normal-hearing and cochlear implant subjects. The latter preferred an audio mix with larger vocals-to-instruments ratio. In addition, given an audio mix with clear vocals and attenuated instruments, cochlear implant subjects preferred the bass/drum track to be louder than the other instrument tracks. Conclusions: The original audio mix in real-world music might not be suitable for cochlear implant recipients. Modifying the relative instrument level settings potentially improves music enjoyment. © 2014 British Society of Audiology, International Society of Audiology, and Nordic Audiological Society.


PubMed | SCIC Cochlear Implant Program, Cochlear Limited, Hear and Say, Royal Melbourne Hospital and 4 more.
Type: | Journal: International journal of pediatric otorhinolaryngology | Year: 2016

The aim of this study was to investigate whether experienced paediatric cochlear implant users could show benefits to speech perception outcomes from the introduction of noise reduction and automated scene classification technologies as implemented in the Nucleus() 6 sound processor. Previous research with adult cochlear implant users had shown significant improvements in speech intelligibility for listening in noisy conditions and good user acceptance for upgrading to the Nucleus 6 processor. In adults, these improvements for listening in noise were primarily attributed to the use of a range of new input processing technologies including noise reduction, as well as introduction of automatic scene classification technology.Experienced paediatric cochlear implant users (n=25) were recruited from four clinics located in three countries. Research participants were evaluated on three occasions, an initial session using their Nucleus 5 sound processor; a second session in which participants used the Nucleus 6 processor programmed with the same technologies as were used in their Nucleus 5 sound processor; and a final session in which participants used the Nucleus 6 processor programmed with the default technologies including automatic scene classification (SCAN) which automatically selects the microphone directionality, noise reduction (SNR-NR), and wind noise reduction (WNR) technologies. Prior to both the second and third evaluations, research participants had approximately two weeks take-home experience with the new system. Speech perception performances on monosyllabic word tests presented in quiet and in noise, and a sentence test presented in noise, were compared across the three processor conditions. Acceptance of the Nucleus 6 default settings was assessed in a final session.No group mean difference in performance was found for monosyllabic words in quiet. A significant improvement in speech perception was found for both monosyllabic words and sentences in noise with the default Nucleus 6 program condition as compared with the Nucleus 5 condition. No acceptance issues were noted for any of the children.Experienced paediatric cochlear implant users showed a significant improvement in speech perception in listening in noise when upgraded to the Nucleus 6 sound processor primarily due to the introduction of a noise reduction technology, and all children accepted the default program. These findings suggest that school-aged children may benefit from upgrading to the Nucleus 6 sound processor using the default program.


PubMed | University Hospitals Leuven, Catholic University of Leuven, Cleveland Clinic and Cochlear Technology Center Belgium
Type: Journal Article | Journal: PloS one | Year: 2016

Severe to profound mixed hearing loss is associated with hearing rehabilitation difficulties. Recently, promising results for speech understanding were obtained with a direct acoustic cochlear implant (DACI). The surgical implantation of a DACI with standard coupling through a stapedotomy can however be regarded as challenging. Therefore, in this experimental study, the feasibility of direct acoustic stimulation was investigated at an anatomically and surgically more accessible inner ear site. DACI stimulation of the intact, blue-lined and opened lateral semicircular canal (LC) was investigated and compared with standard oval window (OW) coupling. Additionally, stapes footplate fixation was induced. Round window (RW) velocity, as a measure of the performance of the device and its coupling efficiency, was determined in fresh-frozen human cadaver heads. Using single point laser Doppler vibrometry, RW velocity could reliably be measured in low and middle frequency range, and equivalent sound pressure level (LE) output was calculated. Results for the different conditions obtained in five heads were analyzed in subsequent frequency ranges. Comparing the difference in RW membrane velocity showed higher LE in the LC opened condition [mean: 103 equivalent dB SPL], than in LC intact or blue-lined conditions [63 and 74 equivalent dB SPL, respectively]. No difference was observed between the LC opened and the standard OW condition. Inducing stapes fixation, however, led to a difference in the low frequency range of LE compared to LC opened. In conclusion, this feasibility study showed promising results for direct acoustic stimulation at this specific anatomically and surgically more accessible inner ear site. Future studies are needed to address the impact of LC stimulation on cochlear micromechanics and on the vestibular system like dizziness and risks of hearing loss.

Loading Cochlear Technology Center Belgium collaborators
Loading Cochlear Technology Center Belgium collaborators