Klaus Begall

Clinical results of AutoNRT, a completely automatic ECAP recording system for cochlear implants.

Objective: AutoNRT™ is the completely automatic electrically evoked compound action potential (ECAP) measuring algorithm in the recently released Nucleus Freedom cochlear implant system. AutoNRT allows clinicians to automatically record T-NRT profiles that in turn can be used as a guide for initial fitting. The algorithm consists of a pattern recognition part that judges if the traces contain an ECAP and an intelligent flow that optimizes the measurement parameters and finds the ECAP threshold (T-NRT). The objective of this study was to determine how accurate, reliable, and fast the automatic measurements are. Design: Data on more than 400 electrodes were collected as part of the multicenter clinical trial of the Nucleus Freedom cochlear implant system. T-NRT values determined by the algorithm were compared with T-NRT determinations on the same data by different human observers. Also, the time the measurements took was analyzed. Results: In 90% of the cases, the absolute difference between the AutoNRT and the human observer determined T-NRT was less than 9 CL; the median absolute difference was 3 CL. A second experiment, in which a group of human observers were asked to analyze NRT data, showed high variability in T-NRT; in some cases, two experienced clinicians disagreed by more than 30 current levels. Compared with the group, AutoNRT performed as well as the “average” clinician, with the advantage that the AutoNRT threshold determinations are objective. Analysis of the timing data showed an average intraoperative measurement time of less than 20 sec per electrode with a standard deviation of 5 sec, suggesting that the total array of 22 electrodes can be measured intraoperatively in about 7 minutes on average. Conclusions: AutoNRT provides comparable accuracy to an average clinician but with the added benefit of significant time savings over manual recordings. This makes it a valuable tool for clinical measurement of ECAP threshold in cochlear implant recipients.

Comparison of the TEMPO+ ear-level speech processor and the cis pro+ body-worn processor in adult MED-EL cochlear implant users.

A study was conducted to compare the new MED-EL TEMPO+ ear-level speech processor with the CIS PRO+ body-worn processor in the COMBI 40/COMBI 40+ implant system. Speech tests were performed in 46 experienced subjects in two test sessions approximately 4 weeks apart. Subjects were switched over from the CIS PRO+ to the TEMPO+ in the first session and used only the TEMPO+ in the time between the two sessions. Speech tests included monosyllabic word tests and sentence tests via the telephone. An adaptive noise method was used to adjust each subject’s scores to approximately 50%. Additionally, subjects had to complete a questionnaire based on their 4 weeks of experience with the TEMPO+. The speech test results showed a statistically significant improvement in the monosyllabic word scores with the TEMPO+. In addition, in the second session, subjects showed a significant improvement when using the telephone with the TEMPO+, indicating some learning in this task. In the questionnaire, the vast majority of subjects found that the TEMPO+ allows equal or better speech understanding and rated the sound quality of the TEMPO+ higher. All these objective and subjective results indicate the superiority of the TEMPO+ and are mainly attributed to a new coding strategy called CIS+ and its implementation in the TEMPO+. In other words, based on the results of this study, it appears that after switching over from the CIS PRO+ to the TEMPO+, subjects are able to maintain or even improve their own speech understanding capability.

Artificial Petrous Bone Produced by Stereolithography for Microsurgical Dissecting Exercises

Training in microsurgery of the middle ear requires dissecting to be carried out on petrous bone. Human petrous bone structures are not available in adequate quantity to permit extensive practicing. Using synthetic resins, true reproductions of petrous bone can be obtained by means of a stereolithographic method, yielding structures of the petrous part which are highly similar to human bone. Digital data sets are obtained from spiral CT scans, and transferred to CAD systems such that, using stereolithography, petrous bone facsimiles are produced on the parametric model. Any number of such models of an original can be produced. Thus, identical structures can be made available for a wide range of uses. Exercises conducted on artificial petrous bone so produced are equivalent to those carried out on human structures, in terms of material properties and visualisation of anatomic details.

Speech Understanding with the CIS and the n-of-m Strategy in the MED-EL COMBI 40+ System

Speech tests have been performed on 6 subjects for comparing the standard 12-channel continuous interleaved sampling (CIS) strategy (CIS12), the 7-channel CIS strategy (CIS7) and the 7-of-12 strategy in the MED-EL COMBI 40+ system. An ABAB experimental design was used whereby each strategy was reversed and replicated. Speech tests were performed in quiet (vowels, consonants, monosyllables, sentences) and noise (sentences). Results showed that for vowels, CIS12 is significantly superior to CIS7, for consonants and sentences CIS12, CIS7 and 7-of-12 performed equally well, and that for monosyllables 7-of-12 is significantly superior to both CIS12 and CIS7. In addition, 7-of-12 is superior to CIS7 by almost the same amount as CIS12, but in this case the difference is not significant. Further, all strategies have been found to be equally robust in noise with respect to sentence understanding. The differences between CIS12 and 7-of-12 on the one hand and CIS7 on the other hand may be attributed to decreased spectral resolution of the latter. The fact that – in contrast to what has been reported for the SPEAK strategy – 7-of-12 is equally robust in noise as the CIS strategies is explained by the use of higher stimulation rates, wider frequency bands and a higher percentage of channels stimulated in each cycle.

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.

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.

Observation of Eardrum Movements during Quasi-Static Pressure Changes by High-Speed Digital Imaging

Under specific quasi-static pressure conditions during the Valsalva manoeuvre, high-speed digital video pictures of eardrum displacements were recorded using an endoscope and a Kodak Image Ektapro 1000 Motion Analyzer. A new type of data interface enabled the complete videoclip to be saved and processed digitally, and, with special mathematical algorithms, it is possible to generate three-dimensional computer animations of eardrum movements under quasi-static pressure. The present study describes patterns of eardrum movements under static pressure changes (Valsalva manoeuvre). These patterns were consistent with the results of finite-element simulations of highly similar eardrum displacements reported by other workers.

High-Speed Digital Videoimaging of Fast Eardrum Motions During Valsalva Maneuver

Digital high-speed camera systems are used to record high-frequency videoclips. After adapting this technology to the analysis of eardrum motions, fast motions of the eardrum can be recorded using an endoscope. Under specific static pressure conditions during the Valsalva maneuver, recordings of eardrum motions were made. The use of a Kodak Image Ektapro 1000 Motion Analyzer allowed only conventional videosignal processing and storage. A new type of data interface made it possible to save and process the complete videoclip digitally. Using an image-processing workstation and special mathematical algorithms, three-dimensional computer animations of fast eardrum motions under static pressure can be generated. In the present study, several animations of fast eardrum movements are described. High-speed digital videoimaging is an adequate method to describe fast eardrum displacements under static pressure (Valsalva maneuver). It is possible to create visible time-shift images of separate eardrum parts during the fast Valsalva maneuver.

Population-based cross-sectional study to assess newborn hearing screening program in central Germany

OBJECTIVES Early diagnosis of congenital hearing loss is fundamental to minimize the negative consequences on the speech development. To lower the age at diagnosis and at intervention in hearing impaired children, not only universal newborn hearing screening (NHS) but also tracking is considered essential. The aim of the study was to evaluate the first six years after implementation of the population based newborn hearing screening program in Saxony-Anhalt, one German Federal State. METHODS The cross-sectional cohort study consisted of three cohort samples. Overall 102,301 infants born between January 2010 and December 2015 were included. NHS protocol was developed as dual target group protocol with two sub-protocols. The screening technique included Transient Evoked Otoacoustic Emissions (TEOAE) and Automated Auditory Brainstem Response (AABR) test. Newborns were assigned to the sub-protocols according to their audiological risk factors. Additionally, to evaluate the quality of NHS and tracking (false-negative screening) we were analysing data from a cohort of hearing impaired children diagnosed up to the age of three years. We calculated quality indicators and compared them with international guidelines. RESULTS 101,102 (98.8%) infants were screened. The prevalence of bilateral neonatal hearing loss was 2.32 per 1000 newborns. The median age was two days at first screening, three month at diagnostic testing, and four month at intervention onset. 2.6% infants were lost to follow-up. 56.3% had a final diagnosis of bilateral sensorineural hearing loss. The sensitivity of 0.85 (KI 95%: 0.76–0.91) and a specificity of 0.84 (KI 95%: 0.84–0.85) was calculated for the NHS program. CONCLUSIONS The analysis of benchmarks and outcomes of NHS demonstrated that the program reaches its main goal to identify the hearing impaired newborns in a timely manner.

Resonant Frequency Pattern in Multifrequency Tympanograms: Results in Normally-Hearing Subjects: Patrón de resonancia frecuencial en timpanogramas de multifrecuencia: Resultados en normoyentes

This paper presents experimental data on the evaluation of middle ear resonances by multifrequency tympanometry. Multifrequency tympanograms (MFTs) of 18 normally-hearing subjects were recorded with a frequency resolution of 15 Hz. The fine structure found in the MFT patterns was compared with findings in literature. A first approach for the evaluation of this fine structure was made explaining the great variability of the main ossicular resonance frequencies described in previous publications. The consequence of the present investigation is that the concept of the main ossicular resonance has to be revised critically.

Acoustically and Electrically Evoked Auditory Brainstem Responses

In early models of the generation of the human auditory brainstem response (ABR), the successive components were considered to arise in consecutive structures of the auditory pathway (e.g. Lev and Sohmer, 1972). Waves I, II, III, IV, and V were in particular believed to originate from the 8th nerve, cochlear nuclei, superior olivary complex, lateral lemniscus and inferior colliculus, respectively. The sources of the latest ABR constituents, i.e. of Waves VI and VII, were connected to still further relays: the medial geniculate body and the acoustic radiation, respectively. Later, these early models underwent alterations (Kevanishvili, 1980; Caird and Klinke, 1984). Both neurophysiological and neurosurgical evidence was presented substantiating subcollicular or even sublemniscal origin of the main ABR complex waves including Wave V. The loci of generation of the successive components were shifted downward in proportion. Wave VI, for instance, has been stated to be related to the inferior colliculus (Hall, 1992). Recording of electrically evoked ABR in cochlear implant patients offers a unique opportunity to revise the models of ABR generation.