Auditory Spatial Discrimination and Sound Localization in Single-Sided Deaf Participants Provided with a Cochlear Implant.

INTRODUCTION: Spatial hearing is most accurate using both ears, but accuracy decreases in persons with asymmetrical hearing between ears. In participants with deafness in one ear but normal hearing in the other ear (single-sided deafness [SSD]), this difference can be compensated by a unilateral cochlear implant (CI). It has been shown that a CI can restore sound localization performance, but it is still unclear to what extent auditory spatial discrimination can be improved. METHODS: The present study investigated auditory spatial discrimination using minimum audible angles (MAAs) in 18 CI-SSD participants. Results were compared to 120 age-matched normal-hearing (NH) listeners. Low-frequency (LF) and high-frequency (HF) noise bursts were presented from 4°, 30°, and 60° azimuth on the CI side and on the NH side. MAA thresholds were tested for correlation with localization performance in the same participants. RESULTS: There were eight good performers and ten poor performers. There were more poor performers for LF signals than for HF signals. Performance on the CI side was comparable to performance on the NH side. Most difficulties occurred at 4° and at 30°. Eight of the good performers in the localization task were also good performers in the MAA task. Only the localization ability at 4° on the CI side was positively correlated with the MAA at that location. CONCLUSION: Our data suggest that a CI can restore localization ability but not necessarily auditory spatial discrimination at the same time. The ability to discriminate between adjacent locations may be trainable during rehabilitation to enhance important auditory skills.

Triple Semi-Circular Canal Occlusion and Cochlear Implantation: A Treatment Option for Single-Sided Menière's Disease with Functional Deafness-A Case Series.

The surgical options for patients with single-sided Menière's disease and functional deafness are challenging. Our case series reports the outcomes of surgical treatments of patients with single-sided Menière's disease and functional deafness. These patients have undergone a one-staged occlusion of all semi-circular canals and cochlear implantation. Five patients (four female and one male; 62 ± 8.2 years with a range from 50 to 72 years) with single-sided Menière's disease and functional deafness were included in this study. In all cases, the patients suffered from frequent rotational vertigo episodes for many years. Other treatment options (e.g., medication) had not yet been successful. Preoperatively, the Dizziness Handicap Inventory (DHI) of all patients indicated severe emotional, physical, and functional deficits. Patients showed a functional (near-total) deafness of the affected ear in all cases. All patients were supplied with cochlear implants in combination with a triple occlusion of all semi-circular canals in a one-stage procedure. After a short period of increased dizziness following surgery and after the activation of the cochlear implant and CI rehabilitation (auditory-verbal therapy), vertigo control and an adequate audiological outcome were achieved. The DHI showed a constant decrease after surgery. The combination of a triple semi-circular canal occlusion and cochlear implantation can be an efficient treatment for patients with single-sided Menière's disease.

Minimizing Intracochlear Pressure: Influence of the Insertion Sheath.

OBJECTIVE: Atraumatic cochlear implantation (CI) and insertion of the electrode in particular are major goals of recent CI surgery. Perimodiolar electrode arrays need a stylet or exosheath for insertion. The sheath can influence the intracochlear pressure changes during insertion of the electrode. The aim of this study was to modify the insertion sheath to optimize intracochlear pressure changes. METHODS: In an artifical cochlear model, 7 different modified insertion sheaths were used. The intracochlear pressure was measured with a micro-optical sensor in the apical part of the model cochlea. RESULTS: Significant lower intracochlear pressure changes were observed when the apical part of the insertion sheath was either shortened or tapered. Modification of the stopper does influence the intracochlear pressure significantly. CONCLUSION: Modification of the insertion sheath leads to lower intracochlear pressure gain. The differences and impact on intracochlear pressure changes found in this study underline the importance of even subtle modifications of the electrode insertion technique.

Correction to: Constant severe imbalance following traumatic otoconial loss: a new explanation of residual dizziness.

The original article was updated.

Constant severe imbalance following traumatic otoconial loss: a new explanation of residual dizziness.

Benign paroxysmal positional vertigo (BPPV) is the most common type of vertigo, caused by otoconia falling from the utricle into a semicircular canal (SCC). After successful repositioning maneuvers residual dizziness (RD) has been described and several reasons are used to explain RD. It can last for only a few days or weeks, but also much longer. We present a patient with a severe traumatic loss of otoconia from both maculae utriculi and a persistent imbalance more than 9 years. We think that the loss of otoconia from the utricular and probably also saccular macula induced a sudden reduction of her ability to sense gravity thus logically explaining her symptoms. We show the vestibular test results also supporting our hypothesis and we extrapolate this support to other forms of so far unexplained dizziness especially increasing imbalance with aging. We also discuss the normal c- and oVEMP indicating intact haircell function and supporting our hypothesis of isolated otoconial loss as the major cause for imbalance.

[The sensitivity and specificity of the Mini-Audio-Test (MAT) for different levels of hearing loss]. / Die Sensitivität und Spezifität des Mini-Audio-Tests (MAT) für unterschiedliche Hörverlustschwellen.

BACKGROUND: An untreated hearing impairment could have a severe influence on the morbidity. The Mini-Audio-Test (MAT) has been developed for early detecting of a relevant hearing loss. This follow-up investigation should determine the sensitivity, specificity, and the predictive values for a minimum-level of detected hearing loss of 25, 30, 35, and 40 dB, both, in one octave-frequency between 0.5 and 4 kHz and the average of hearing loss for these four frequencies. METHODS: This survey uses data which were collected in 2016 and 2017. 943 patients parted into two groups (aged 50 to 59 years and aged 60 years and more), were investigated using the MAT. Statistical analysis on the sensitivity, specificity, and predictive values in respect were done as proportions together with the 95 %-confidence interval by a logistic regression. RESULTS: The sensitivity of the MAT was increasing in both groups of age by increasing the minimum of to be detected hearing loss. The specificity was decreasing as well, but less. The positive predictive values were higher for the older age-group and are decreasing by increasing of the minimum of to be detected hearing loss. In general, the values using the averaged hearing loss are noticeably lower than for the single frequency detecting. The values for the negative predictive values were contrary. CONCLUSION: The results for persons aged 60 years and more are worse than for the younger. Therefore, a first screening on hearing loss starting at the age of 50 years seems to be recommended urgently. Only by this, a sufficient rehabilitation of the hearing loss could be done in time so that the negative consequences of an untreated hearing impairment could be influenced positively.

Intracochlear Pressure Changes After Cochlea Implant Electrode Pullback-Reduction of Intracochlear Trauma.

OBJECTIVE: Different aspects should be considered to achieve an atraumatic insertion of cochlear implant electrode arrays as an important surgical goal. Intracochlear pressure changes are known to influence the preservation of residual hearing. By using the intraoperative "pullback technique," an electrode position closer to the modiolus can be achieved than without the pullback. The aim of the present study was therefore to investigate to what extent the pullback technique can influence intracochlear pressure changes. METHODS: Insertions of cochlear implant electrodes were performed in an artificial cochlear model with two different perimodiolar arrays. Intracochlear pressure changes were recorded with a micro-optical pressure sensor positioned in the apical part of the cochlear. After complete insertion of the electrode array, a so-called pullback of the electrode was performed. RESULTS: Statistically significant pressure differences were measured if the electrode array was wet (ie, moisturized) during the pullback. Relative pressure changes in electrodes with smaller total volume are lower than pressure changes in larger electrodes. CONCLUSION: The preservation of residual hearing and, thus, the resulting postoperative audiological outcome has a major impact on the quality of life of the patients and has become of utmost importance. Intracochlear pressure changes during the pullback manoeuver are small in absolute terms, but can even be still reduced statistically significantly by a moistening the electrode before insertion. Using the pullback technique in cases with residual hearing does not affect the probability of preservation of residual hearing but could lead to a better audiological outcome. LEVEL OF EVIDENCE: NA.

Electric acoustic stimulation (EAS) with the Naída CI Q90 sound processor in experienced cochlear implant users.

Objectives: The benefit of using the electroacoustic functionality was tested compared to electric stimulation alone. Two different cut-off frequencies between acoustic and electric stimulation were tried. Methods: Performance and subjective preference in 10 subjects was measured with electric only and electroacoustic stimulation with two settings: a cut-off for acoustic amplification at the frequency where thresholds exceeded 70 dB and 85 dB. An overlapping setting was also tried in five participants. Results: There was a non-significant trend with a median improvement in SRT of 1.3 dB (70 dB cut-off) and 0.8 dB (85 dB cut-off) compared to the electric only condition. From nine subjects who completed the study, one preferred the 85 dB cut-off frequency, with the others preferred either a 70 dB cut-off or an overlapping setting. Discussion: Nine subjects continued to use the EAS processor after study termination because of subjective benefits. The variability in speech outcomes and subjective preference is underlining the importance of being able to manually change acoustic and electric cut-off frequencies. Conclusion: There were non-significant median group benefits from use of the acoustic component for these existing CI users. A hearing loss of 70 dB HL is an appropriate default cut-off frequency in the fitting software.

Evaluation of a wireless contralateral routing of signal (CROS) device with the Advanced Bionics Naída CI Q90 sound processor.

Objectives: Cochlear implants (CIs) usually provide severe to profoundly deaf recipients with speech intelligibility in quiet. In difficult listening situations such as background noise however, communication often remains challenging. For unilateral CI recipients with a bilateral hearing loss, speech intelligibility for speech sources on the non-implanted side is further impaired by the head-shadow effect. One possibility to overcome this impairment is the use of Contralateral Routing of Signal (CROS) systems, which capture sounds from the non-implanted side and (wirelessly) transmit them to the implant processor, therefore increasing audibility. Such a CROS system was evaluated in this study. Methods: Speech intelligibility in noise was measured in several spatial listening setups using the Oldenburg matrix sentence test in ten cochlear implant users. Performance was compared between listening with the CI alone and listening with the CI in combination with a wireless CROS device. Following an extended trial phase, subjective feedback regarding the device benefit in everyday life was collected via the Bern Benefit in Single Sided Deafness (BBSS) questionnaire. Results: The addition of the wireless CROS device significantly improved speech intelligibility by 7.2 dB (median) in spatial noise. Using advanced directional microphones, a statistically significant benefit of 4.4 dB (median) could be shown in a diffuse noise field. Responses to the BBSS questionnaire revealed that subjects perceived benefit in their everyday lives when using the CROS device with their CI. Conclusion: The investigated CROS system presents a valuable addition to a unilateral CI in cases where bilateral implantation is not an option.

Benefit of directional microphones for unilateral, bilateral and bimodal cochlear implant users.

OBJECTIVE: To compare the standard T-Mic setting to UltraZoom and StereoZoom in 10 unilateral cochlear implant (CI) users, 10 bimodal device users and 10 bilateral CI users as well as a normal hearing (NH) reference group (n = 10). METHOD: Speech reception thresholds were measured using the Oldenburg sentence test in noise. Speech was presented from the front at 0°, noise was presented from five loudspeakers spaced at ±60°, ±120°, 180° (setup A) or from four loudspeakers in the front hemisphere at ±30°, ±60° and one at 180° (setup B). RESULTS: There was a significant advantage for UltraZoom and StereoZoom for all groups in both setups. The largest advantage was for StereoZoom in the bilateral group (setup A, 5.2 dB, P < 0.001 and B, 3.4 dB, P < 0.001) There was a significant advantage for StereoZoom over UltraZoom in the bimodal group (setup A, P < 0.01 and B, P < 0.05) and in the bilateral group (P < 0.01, setup B only). The bilateral group performed as well as the normally hearing group in both setups and the bimodal group performed as well in setup A. There was a significant benefit of 1.8 dB for ClearVoice over UltraZoom alone for the unilateral group. CONCLUSIONS: UltraZoom and StereoZoom provided a clinically and statistically significant benefit over the T-Mic condition. The largest gain was shown for StereoZoom in the bimodal and bilateral groups. The use of StereoZoom enabled the bilateral group to perform as well as the normally hearing group in both the challenging speaker setups. However, real life environments might provide an even greater challenge than the conditions tested here.

[The Mini-Audio-Test (MAT) - a screening method on hearing impairment to be used by general practitioners and specialized physicians]. / Der Mini-Audio-Test (MAT) ­ eine Screeningmethode auf Schwerhörigkeit für Haus- und Fachärzte.

BACKGROUND: In Germany, about 15 million people are suffering from hearing loss (HL), whereas only 16 % are using hearing aids. Untreated hearing loss may lead to severe complications (e. g. social isolation, depression, progress of dementia). An early and widespread screening, beginning at the age of 50, is meant to improve this shortage in medical care. By this study, the Mini-Audio-Test (MAT), a six-question and three-step answers containing questionnaire on subjective HL, should be verified on a normal collective of subjects (sensitivity (Se), specificity (Sp), positive predictive value (Ppv)). METHODS: 943 subjects (older 50 years) without any history of ear disease answered the MAT and received pure-tone audiometry. The Se, Sp, and Pv to detect a relevant HL with the MAT for the age-group < 60 years (AG1) and ≥ 60 years (AG2) were determined. RESULTS: The Se for AG1 was 0.66, the Sp 0.61, the Ppv 0.60, for AG2 the Se was 0.47, the Sp 0.80, the Ppv 0,89. CONCLUSION: Following our results, the MAT is recommended as a general screening-tool for HL in patients over 50 years of age for general practitioners. Hereby, severe secondary diseases (loss of cognitive power, risk of fall, depression, dementia) could be influenced positively.

Magnetic Resonance Imaging Artifacts and Cochlear Implant Positioning at 1.5 T In Vivo.

OBJECTIVE: Cerebral magnetic resonance imaging with the magnet of the cochlear implant receiver/stimulator in place causes artifacts and hinders evaluation of intracerebral structures. The aim of this study was to evaluate the internal auditory canal and the labyrinth in a 1.5T MRI with the magnet in place. STUDY DESIGN: Observational study. SETTING: Tertiary referral center. SUBJECTS AND METHODS: The receiver/stimulator unit was placed and fixed onto the head of three volunteers at three different angles to the nasion-outer ear canal (90°-160°) and at three different distances from the outer ear canal (5-9 cm). T1 and T2 weighted sequences were conducted for each position. RESULTS: Excellent visibility of the internal auditory canal and the labyrinth was seen in the T2 weighted sequences with 9 cm between the magnet and the outer ear canal at every nasion-outer ear canal angle. T1 sequences showed poorer visibility of the internal auditory canal and the labyrinth. CONCLUSION: Aftercare and visibility of intracerebral structures after cochlear implantation is becoming more important as cochlear implant indications are widened worldwide. With a distance of at least 9 cm from the outer ear canal the artifact induced by the magnet allows evaluation of the labyrinth and the internal auditory canal.

Hearing Outcomes after Transmastoid Plugging of Superior Canal Dehiscence.

BACKGROUND: Patients with a superior canal dehiscence syndrome display symptoms of the vestibular disorder except that of hearing loss. Therefore, any type of surgery should treat those symptoms without affecting the hearing threshold. The aim of this study was to evaluate the extent to which the hearing threshold has been affected; the evaluation process was carried out by a transmastoid plugging of the superior canal. Another aim was to estimate the risk in loss of hearing due to this surgery. MATERIAL AND METHODS: In a retrospective study, 31 patients with dehiscence of the superior canal, who underwent a transmastoid plugging, were included. Additionally, 8 of them with the clinical symptoms of the Menière's disease received an endolymphatic sac surgery. A b-c threshold at 0.25, 0.5, 1, 2, and 4 kHz was observed in all patients pre and postoperatively as well as in the long-term follow-up. RESULTS: After a mean interval of 149 days, a change in the b-c threshold of 5.9 dB was detected. After 149 days, in the patient group comprising those who underwent an additional endolymphatic sac surgery, a b-c threshold change of 17.18 dB was detected. CONCLUSION: The transmastoid plugging of the superior semicircular canal can be performed with an acceptable risk of hearing affection. If the surgery was combined with other techniques, (e.g. endolymphatic sac surgery) then the risk increases.

Long-Term Outcomes of Vibroplasty Coupler Implantations to Treat Mixed/Conductive Hearing Loss.

OBJECTIVE: To evaluate the long-term safety and performance of four different vibroplasty couplers (round window, oval window, CliP and Bell coupler) in combination with an active middle ear implant. METHODS: This was a multicentre, prospective, long-term study including 5 German hospitals. Thirty adult subjects suffering from conductive or mixed hearing loss were initially enrolled for the study, 24 of these were included in the final analysis with up to 36 months of postsurgical follow-up data. Bone conduction and air conduction were measured pre- and postoperatively to evalu ate safety. Postoperative aided sound field thresholds and Freiburger monosyllable word recognition scores were compared to unaided pre-implantation results to confirm performance. Additional speech tests compared postoperative unaided with aided results. To determine patient satisfaction, an established quality-of-life questionnaire developed for conventional hearing aid usage was administered to all subjects. RESULTS: Mean postoperative bone conduction thresholds remained stable throughout the whole study period. Mean functional gain for all couplers investigated was 38.5 ± 11.4 dB HL (12 months) and 38.8 ± 12.5 dB HL (36 months). Mean word recognition scores at 65 dB SPL increased from 2.9% in the unaided by 64.2% to 67.1% in the aided situation. The mean postoperative speech reception in quiet (or 50% understanding of words in sentences) shows a speech intelligibility improvement at 36 months of 17.8 ± 12.4 dB SPL over the unaided condition. The signal-to-noise ratio (SNR) improved by 5.9 ± 7.2 dB SNR over the unaided condition. High subjective device satisfaction was reflected by the International Inventory for Hearing Aids scored very positively. CONCLUSION: A significant improvement was seen with all couplers, and audiological performance did not significantly differ between 12 and 36 months after surgery.

Evaluation of Cochlear Implant Receiver Position and Its Temporal Changes.

HYPOTHESIS: It was the aim of this study to establish normative data regarding intended changes in cochlear implants (CI) receiver positioning by one surgeon over time. BACKGROUND: With the increasing number of CI patients, the probability of needing magnetic resonance imaging (MRI) increases. The accessibility of cerebral structures is limited by MRI artifacts caused by CI. New studies show a dependence of the visibility of intracranial structures by the MRI sequences and the position of the CI receiver itself. METHODS: Retrospective and interindividual investigation of topograms with regard to the nasion-external auditory canal-internal magnet angle and the distance between the internal magnet and the external auditory canal. We evaluated scans of 150 CI recipients implanted from 2008 until 2015. RESULTS: The most common implant position in the years 2008 to 2015 was a nasion-external auditory canal-internal magnet angle between 121 and 140 degrees (mean, 127 degrees) and an internal magnet-external auditory canal distance between 61 and 80 mm (mean, 70 mm). Over time the nasion-external auditory canal-internal magnet angle increased and the internal magnet-external auditory canal distance decreased, both to a statistically significant degree. A difference between the manufacturers was not observed. CONCLUSION: The CI receiver position is important for an artifact-free examination of the internal auditory canal and the cochlea. The realization of the position over a time course supports awareness of artifact-related visibility limitations.

Surgical treatment of vertigo in cochlear implantees by electrode resealing.

CONCLUSION: Our present findings demonstrate that resealing to cover the electrode is an effective method to treat vertigo after CI. An insufficient cochleostomy sealing can be regarded as a cause of postoperatively newly occuring vertigo after CI. A transtympanic revision is a promising treatment option in cases of post-operative dizziness. Intoduction: A well-known and frequently reported complication after cochlear implantation is the appearance of postoperative vertigo symptoms. The aim of the present study was to observe if the postoperatively new occurrence of vertigo can be treated by resealing of the round window patch after cochlear implantation. MATERIAL AND METHODS: A retrospective analysis revealed that 10 patients underwent revision surgery transtympanally. Vertigo was assessed preoperatively and directly postoperatively and after 6 month after revision surgery by using the Dizziness Handycap Inventory (DHI). RESULTS: The most common symptom was rotating vertigo. A spontanous nystagmus was seen in four cases. No nystagmus was found after the revision surgery. In three cases, the onset of dizziness was associated with an event (sneezing, otitis media, climbing a mountain). A preoperative CT showed insuspectible results in seven patients but revealed pathologies two patients. Vertigo was improved significantly in six patients, and three of them were symptom-free.

Radiological and NRT-Ratio-Based Estimation of Slim Straight Cochlear Implant Electrode Positions: A Multicenter Study.

OBJECTIVES: An intraoperative neural response telemetry-ratio (NRT-ratio) was established, which can provide information about the intraoperative intracochlear electrode array position for perimodiolar electrodes. METHODS: In a retrospective controlled study in 2 tertiary referral centers, the electrophysiological data sets of 50 patients with measured intraoperative auto-NRTs and postoperative radiological examinations were evaluated. All patients were implanted with Nucleus slim straight electrodes. The NRT-ratio was calculated by dividing the average auto-NRT data from electrodes 16 to 18 with the average from electrodes 5 to 7. Using a flat panel tomography system or a computed tomography, the position of the electrode array was certified radiological. RESULTS: Radiologically, 2 out of 50 patients were identified with an electrode translocated from the scala tympani into the scala vestibuli. The radiologically estimated electrodes indicating a scalar change showed a regular NRT-ratio but nonspecific NRT-level changes at the localization of translocation.

Insertional depth-dependent intracochlear pressure changes in a model of cochlear implantation.

CONCLUSION: Over time, a homogenous increase in intracochlear pressure was seen in every experiment. Significant reductions in terms of amplitude variation and insertion depth were observed over time, using the one-point-supported insertion method. The frequency of peaks between the thirds was significantly lower when using the two-points-supported insertion method. OBJECTIVES: The preservation of residual hearing and minimization of intracochlear trauma are two of the major goals in modern cochlear implantation (CI) surgery. It is assumed that intracochlear pressure measurements yield information about the intracochlear behavior of the electrode itself in the cochlea. The aim of this study was to investigate temporal intracochlear fluid pressure changes using two different kinds of insertion conditions. METHOD: Cochlear implantations with the Advanced Bionics IJ® electrode were performed in an artificial cochlear model with a constant insertional speed of 0.5 mm/s provided by a linear actor. Amplitude pressure changes and number of pressure peaks were evaluated for every part. RESULT: Intracochlear fluid pressure changes are assumed to affect the preservation of residual hearing and should be minimized. The stability and reduction of movement of a lateral wall IJ® electrode increase at deeper insertion and affect intracochlear fluid pressure amplitude.

Comparison of the effects of four different cochlear implant electrodes on intra-cochlear pressure in a model.

CONCLUSION: Based on this model experiment, a small tip and low volume electrode show lowest intra-cochlear pressure values. Insertional support by a tool minimizes fast pressure changes. Higher electrodes volumes affect slow and fast pressure changes as well. OBJECTIVE: Insertion causing low intra-cochlear pressure is assumed to be important for atraumatic cochlear implant surgery to preserve residual hearing. Cochlear implant electrodes differ in terms of parameters like tip size, length, volume, and technique of insertion. The aim of this study was to observe the effect of different cochlear implant electrodes on insertional intra-cochlear pressure in a cochlear model. MATERIALS AND METHODS: Cochlear implant electrode insertions were performed in an artificial cochlear model and intra-cochlear pressure changes were recorded in parallel with a micro-pressure sensor positioned in the apical region of the cochlear model to follow the maximum values, temporal changes, maximum amplitude, and frequency of changes in intra-cochlear pressure. Insertions were performed with four different electrodes (Advanced Bionics 1j, Helix, HFMS, and LW23). RESULTS: This study found statistically significant differences in the occurrence of initial maximum pressure values correlating with the electrode tip size. The different electrodes and the technique of insertion significantly affected the occurrence of maximum value, amplitude, and frequency of intra-cochlear pressure occurrence.

Intracochlear Pressure Changes due to 2 Electrode Types: An Artificial Model Experiment.

Objective To preserve residual hearing in cochlear implant surgery, the electrode design has been refined, and an atraumatic insertion has become one aspect of cochlear implant research. Previous studies have described the effect of insertion speed and opening of the round window membrane on intracochlear pressure changes. The aim of our current study was to observe intracochlear pressure changes due to different cochlear implant electrodes in an artificial cochlear model with stable surrounding factors. Study Design Prospective controlled study. Setting Tertiary referral center. Subjects and Methods The experiments were performed in an artificial cochlear model with a pressure sensor in the apical area. With straight and perimodiolar electrode arrays, 5 insertions with the same insertion speed and 5 insertions over the same time were performed. Results With the perimodiolar high-volume electrode, significantly greater intracochlear fluid pressure changes were observed than with the straight electrode. Compared with the straight electrode, the perimodiolar electrode induces significantly higher pressure peaks (1.12 ± 0.15 vs 0.86 ± 0.05 mm Hg, P = .006) and significantly higher amplitudes (0.38 ± 0.07 vs 0.09 ± 0.07 mm Hg, P < .001). Conclusion The reliable preservation of residual hearing is an important multifactorial challenge in modern cochlear implant surgery. Insertion speed, handling, and electrode design are known to influence the preservation of residual hearing. In our artificial model experiments, we could prove objectively that the volume of the electrodes has a significant influence on the intracochlear pressure changes during cochlear implantation.