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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. Source


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. Source


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. Source


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. Source


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. Source

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