Masked Speech Perception with Bone Conduction Device, Contralateral Routing of Signals Hearing Aid, and Cochlear Implant Use in Adults with Single-Sided Deafness: A Prospective Hearing Device Comparison using a Unified Testing Framework.

INTRODUCTION: For the treatment of single-sided deafness (SSD), common treatment choices include a contralateral routing of signals (CROS) hearing aid, a bone conduction device (BCD), and a cochlear implant (CI). The primary aim of this study was to compare speech understanding in noise and binaural benefits in adults with postlingual SSD between preoperative unaided baseline, preoperative CROS and BCD trial devices, and CI, following recommendations from a consensus protocol. In addition, we investigated the effect of masker type on speech understanding. METHODS: This was a prospective study with twelve participants. Binaural effects of head shadow, squelch, summation, and spatial release from masking were assessed by measuring speech reception thresholds (SRTs) in five different spatial target-masker configurations using two different maskers: two-talker babble (TTB), and speech-shaped noise (SSN). Preoperatively, participants were assessed unaided and with CROS and BCD trial devices. After cochlear implantation, participants were assessed at 1, 3, and 6 months post-activation. RESULTS: For TTB, significant improvements in SRT with a CI relative to preoperatively unaided were found in all spatial configurations. With CI at 6 months, median benefits were 7.8 dB in SSSDNAH and 5.1 dB in S0NAH (head shadow), 3.4 dB in S0N0 (summation), and 4.6 dB in S0NSSD and 5.1 dB in SAHNSSD (squelch). CROS yielded a significant head shadow benefit of 2.4 dB in SSSDNAH and a significant deterioration in squelch of 2.5 dB in S0NSSD and SAHNSSD, but no summation effect. With BCD, there was a significant summation benefit of 1.5 dB, but no head shadow nor squelch effect. For SSN, significant improvements in SRT with CI compared to preoperatively unaided were found in three spatial configurations. Median benefits with CI at 6 months were: 8.5 dB in SSSDNAH and 4.6 dB in S0NAH (head shadow), 1.4 dB in S0N0 (summation), but no squelch. CROS showed a significant head shadow benefit of 1.7 dB in SSSDNAH, but no summation effect, and a significant deterioration in squelch of 2.9 dB in S0NSSD and 3.2 dB in SAHNSSD. With BCD, no binaural effect was obtained. Longitudinally, we found significant head shadow benefits with a CI in SSSDNAH in both maskers at all postoperative intervals and in S0NAH at 3 and 6 months post-activation. CONCLUSION: With a CI, a clear benefit for masked speech perception was observed for all binaural effects. Benefits with CROS and BCD were more limited. CROS usage was detrimental to the squelch effect.

Automatic localization of cochlear implant electrodes using cone beam computed tomography images.

BACKGROUND: Cochlear implants (CI) are implantable medical devices that enable the perception of sounds and the understanding of speech by electrically stimulating the auditory nerve in case of inner ear damage. The stimulation takes place via an array of electrodes surgically inserted in the cochlea. After CI implantation, cone beam computed tomography (CBCT) is used to evaluate the position of the electrodes. Moreover, CBCT is used in research studies to investigate the relationship between the position of the electrodes and the hearing outcome of CI user. In clinical routine, the estimation of the position of the CI electrodes is done manually, which is very time-consuming. RESULTS: The aim of this study was to optimize procedures of automatic electrode localization from CBCT data following CI implantation. For this, we analyzed the performance of automatic electrode localization for 150 CBCT data sets of 10 different types of electrode arrays. Our own implementation of the method by Noble and Dawant (Lecture notes in computer science (Including subseries lecture notes in artificial intelligence and lecture notes in bioinformatics), Springer, pp 152-159, 2015. https://doi.org/10.1007/978-3-319-24571-3_19 ) for automated electrode localization served as a benchmark for evaluation. Differences in the detection rate and the localization accuracy across types of electrode arrays were evaluated and errors were classified. Based on this analysis, we developed a strategy to optimize procedures of automatic electrode localization. It was shown that particularly distantly spaced electrodes in combination with a deep insertion can lead to apical-basal confusions in the localization procedure. This confusion prevents electrodes from being detected or assigned correctly, leading to a deterioration in localization accuracy. CONCLUSIONS: We propose an extended cost function for automatic electrode localization methods that prevents double detection of electrodes to avoid apical-basal confusions. This significantly increased the detection rate by 11.15 percent points and improved the overall localization accuracy by 0.53 mm (1.75 voxels). In comparison to other methods, our proposed cost function does not require any prior knowledge about the individual cochlea anatomy.

Some, but not all, cochlear implant users prefer music stimuli with congruent haptic stimulation.

Cochlear implant (CI) users often report being unsatisfied by music listening through their hearing device. Vibrotactile stimulation could help alleviate those challenges. Previous research has shown that musical stimuli was given higher preference ratings by normal-hearing listeners when concurrent vibrotactile stimulation was congruent in intensity and timing with the corresponding auditory signal compared to incongruent. However, it is not known whether this is also the case for CI users. Therefore, in this experiment, we presented 18 CI users and 24 normal-hearing listeners with five melodies and five different audio-to-tactile maps. Each map varied the congruence between the audio and tactile signals related to intensity, fundamental frequency, and timing. Participants were asked to rate the maps from zero to 100, based on preference. It was shown that almost all normal-hearing listeners, as well as a subset of the CI users, preferred tactile stimulation, which was congruent with the audio in intensity and timing. However, many CI users had no difference in preference between timing aligned and timing unaligned stimuli. The results provide evidence that vibrotactile music enjoyment enhancement could be a solution for some CI users; however, more research is needed to understand which CI users can benefit from it most.

High variability phonetic training facilitates perception-to-production transfer in Mandarin-speaking children with cochlear implants: An acoustic investigation.

This study primarily aimed to evaluate the effectiveness of high variability phonetic training (HVPT) for children with cochlear implants (CIs) via the cross-modal transfer of perceptual learning to lexical tone production, a scope that has been largely neglected by previous training research. Sixteen CI participants received a five-session HVPT within a period of three weeks, whereas another 16 CI children were recruited without receiving any formal training. Lexical tone production was assessed with a picture naming task before the provision (pretest) and immediately after (posttest) and ten weeks after (follow-up test) the completion of the training protocol. The production samples were coded and analyzed acoustically. Despite considerable distinctions from the typical baselines of normal-hearing peers, the trained CI children exhibited significant improvements in Mandarin tone production from pretest to posttest in pitch height of T1, pitch slope of T2, and pitch curvature of T3. Moreover, the training-induced acoustic changes in the concave characteristic of the T3 contour was retained ten weeks after training termination. This study represents an initial acoustic investigation on HVPT-induced benefits in lexical tone production for the pediatric CI population, which provides valuable insights into applying this perceptual training technique as a viable tool in clinical practices.

Frequency importance functions in simulated bimodal cochlear-implant users with spectral holes.

Frequency importance functions (FIFs) for simulated bimodal hearing were derived using sentence perception scores measured in quiet and noise. Acoustic hearing was simulated using low-pass filtering. Electric hearing was simulated using a six-channel vocoder with three input frequency ranges, resulting in overlap, meet, and gap maps, relative to the acoustic cutoff frequency. Spectral holes present in the speech spectra were created within electric stimulation by setting amplitude(s) of channels to zero. FIFs were significantly different between frequency maps. In quiet, the three FIFs were similar with gradually increasing weights with channels 5 and 6 compared to the first three channels. However, the most and least weighted channels slightly varied depending on the maps. In noise, the patterns of the three FIFs were similar to those in quiet, with steeper increasing weights with channels 5 and 6 compared to the first four channels. Thus, channels 5 and 6 contributed to speech perception the most, while channels 1 and 2 contributed the least, regardless of frequency maps. Results suggest that the contribution of cochlear implant frequency bands for bimodal speech perception depends on the degree of frequency overlap between acoustic and electric stimulation and if noise is absent or present.

Recovering speech intelligibility with deep learning and multiple microphones in noisy-reverberant situations for people using cochlear implants.

For cochlear implant (CI) listeners, holding a conversation in noisy and reverberant environments is often challenging. Deep-learning algorithms can potentially mitigate these difficulties by enhancing speech in everyday listening environments. This study compared several deep-learning algorithms with access to one, two unilateral, or six bilateral microphones that were trained to recover speech signals by jointly removing noise and reverberation. The noisy-reverberant speech and an ideal noise reduction algorithm served as lower and upper references, respectively. Objective signal metrics were compared with results from two listening tests, including 15 typical hearing listeners with CI simulations and 12 CI listeners. Large and statistically significant improvements in speech reception thresholds of 7.4 and 10.3 dB were found for the multi-microphone algorithms. For the single-microphone algorithm, there was an improvement of 2.3 dB but only for the CI listener group. The objective signal metrics correctly predicted the rank order of results for CI listeners, and there was an overall agreement for most effects and variances between results for CI simulations and CI listeners. These algorithms hold promise to improve speech intelligibility for CI listeners in environments with noise and reverberation and benefit from a boost in performance when using features extracted from multiple microphones.

Effects of selective stimulation of apical electrodes on temporal pitch perception by cochlear implant recipients.

This study investigated whether selective apical stimulation improves temporal pitch perception in eight MED-EL cochlear implant recipients and whether any such improvement relates to auditory-nerve survival. Three stimulation conditions differing in the place and width of excitation were evaluated: single-electrode stimulation of (i) the most apical, (ii) a mid-array electrode, and (iii) multi-electrode stimulation of the four most apical electrodes. Stimulation-current-induced non-stimulating electrode voltages were recorded to identify extracochlear electrodes and gauge insertion depth. The pitches of the four most apical electrodes were compared using place-pitch ranking. Rate-pitch ranking was assessed between 80 and 981 pulses per second for the three stimulation conditions, to estimate the "upper limit" of temporal pitch. Single-electrode apical stimulation did not increase the upper limit relative to other conditions. The polarity effect (PE), defined as the difference between thresholds obtained for triphasic pulse trains with their central high-amplitude phase either anodic or cathodic, was obtained to evaluate peripheral neural health. The PE did not differ between apical and mid-array stimulation or correlate with the upper limit. In conclusion, we found no improvement of temporal pitch perception with single-electrode apical stimulation, and discuss possible explanations for this observation.

[Online training for hearing implant surgery : A new approach to otological training. German version]. / Online-Training für Hörimplantatchirurgie : Ein neuer Ansatz in der otologischen Ausbildung.

OBJECTIVE: Education in microsurgery of the ear includes staged training to allow for mastering of the complex microsurgical procedures, particularly in the context of middle ear reconstruction and cochlear implantation. Traditional surgical training includes temporal bone preparations by cadaver dissection and supervised operating room practice. As these on-site trainings are limited, there is a need to broaden education facilities in an on-line format. Therefore, a first basic on-line training for otosurgery was developed. MATERIALS AND METHODS: The system consists of an artificial temporal bone model together with a set of basic surgical instruments and implant dummies. As an essential part of the training kit, a high-resolution camera set is included that allows for connection to a video streaming platform and enables remote supervision of the trainees' surgical steps by experienced otological surgeons. In addition, a pre-learning platform covering temporal bone anatomy and instrumentation and pre-recorded lectures and instructional videos has been developed to allow trainees to review and reinforce their understanding before hands-on practice. RESULTS: Over the three courses held to date, 28 participants with varying levels of prior surgical experience took part in this otological surgical training program. The immediate feedback of the participants was evaluated by means of a questionnaire. On this basis, the high value of the program became apparent and specific areas could by identified where further refinements could lead to an even more robust training experience. CONCLUSION: The presented program of an otosurgical online training allows for basal education in practical exercises on a remote system. In this way, trainees who have no direct access to on-site instruction facilities in ear surgery now have the chance to start their otosurgical training in an educational setting adapted to modern technologies.

Acceptance and Benefits of Electro-Acoustic Stimulation for Conventional-Length Electrode Arrays.

BACKGROUND: Prior studies have shown an advantage for electro-acoustic stimulation (EAS) in cochlear implant (CI) patients with residual hearing, but the degree of benefit can vary. The objective was to explore which factors relate to performance with and acceptance of EAS for CI users with conventional-length electrodes. METHODS: A retrospective chart review was conducted for adults with an average threshold of 75 dB hearing loss or better across 250 and 500 Hz preoperatively (n = 83). All patients underwent cochlear implantation with a conventional-length electrode. Low-frequency audiometric thresholds were measured at initial activation as well as 3 and 12 months postoperatively to determine who met the criteria for EAS. Speech perception for CNC words and AzBio sentences in quiet and +10 dB SNR noise was evaluated 3 and 12 months after activation. RESULTS: Speech perception in quiet and noise was similar regardless of whether or not the patient was eligible for EAS. Less than half of the patients who met the EAS criteria chose to use it, citing reasons such as physical discomfort or lack of perceived benefit. EAS users performed better on CNC words but not sentence recognition than EAS nonusers. CONCLUSIONS: EAS use is dependent on audiologic and nonaudiologic issues. Hearing preservation is possible with conventional electrodes, but hearing preservation alone does not guarantee superior speech perception.

Surgical anatomy of basal turn in relation to middle cranial fossa and round window as pertaining to middle fossa cochlear implant technique.

PURPOSE: The purpose of this investigation was to evaluate the relation of the basal turn of cochlea with middle cranial fossa and round window as pertaining to middle cranial fossa cochlear implant technique. METHODS: Fifty-four formalin preserved temporal bones were micro-dissected to expose the basal turn. The point (f) was marked on the basal turn of cochlea where there was minimum distance of basal turn of cochlea from the floor of middle cranial fossa (f1). The f-f1 distance, the angle (∠smf) and distance of point "f" from the round window (s-f) was measured. RESULTS: The mean minimum distance between basal turn of cochlea and floor of middle cranial fossa (f-f1) was 2.0 ± 0.7 mm.The point f was at mean distance (s-f) and angle (∠smf) of 14.7 ± 1.6 mm and 217° ± 13.7° from round window, respectively. CONCLUSIONS: The information may be helpful for designing appropriate electrode array for middle fossa technique especially for deciding the length of electrode array towards round window, as otherwise electrode may extend into vestibule of inner ear. In the cases where bone thickness between superior part of basal turn of cochlea and middle cranial fossa is < 1.5 mm, surgeon should be extra cautious.

Global Regulatory Review Needed for Cochlear Implants: A Call for FDA Leadership.

INTRODUCTION: Using the United States Food and Drug Administration (FDA) as example, we argue that regulatory agencies worldwide should review their guidance on cochlear implants (CIs). METHODS: This is a position paper, thus the methods are strictly argumentation. Here we give the motivation for our recommendation. The FDA's original approval of implantation in prelingually deaf children was granted without full benefit of information on language acquisition, on childcaregiver communication, and on the lived experience of being deaf. The CI clinical trials, accordingly, did not address risks of linguistic deprivation, especially when the caregiver's communication is not fully accessible to the prelingually deaf child. Wide variability in the effectiveness of CIs since initial and updated approval has been indicated but has not led to new guidance. Children need to be exposed frequently and regularly to accessible natural language while their brains are still plastic enough to become fluent in any language. For the youngest infants, who are not yet producing anything that could be called language although they might be producing salient social signals (Goldstein et al. Child Dev 80:636-644, 2009), good comprehension of communication from caregiver to infant is critical to the development of language. Sign languages are accessible natural languages that, because they are visual, allow full immersion for deaf infants, and they supply the necessary support for this comprehension. The main language contributor to health outcomes is this combination of natural visual language and comprehension in communication. Accordingly, in order to prevent possible language deprivation, all prelingually deaf children should be exposed to both sign and spoken languages when their auditory status is detected, with sign language being critical during infancy and early childhood. Additionally, all caregivers should be given support to learn a sign language if it is new to them so that they can comprehend their deaf children's language expressions fully. However, both languages should be made accessible in their own right, not combined in a simultaneous or total communication approach since speaking one language and signing the other at the same time is problematic. RESULTS: Again, because this is a position paper, our results are our recommendations. We call for the FDA (and similar agencies in other countries) to review its approval of cochlear implantation in prelingually deaf children who are within the sensitive period for language acquisition. In the meantime, the FDA should require manufacturers to add a highlighted warning to the effect that results with CI vary widely and CIs should not be relied upon to provide adequate auditory input for complete language development in all deaf children. Recent best information on users' experience with CIs (including abandonment) should be clearly provided so that informed decisions can be made. The FDA should require manufacturers' guidance and information materials to include encouragement to parents of deaf children to offer auditory input of a spoken language and visual input of a sign language and to have their child followed closely from birth by developmental specialists in language and cognition. In this way parents can align with providers to prioritize cognitive development and language access in both audio-vocal and visuo-gestural modalities. DISCUSSION: The arguments and recommendations in this paper are discussed at length as they come up.

Comparative study of two different perimodiolar and a straight cochlear implant electrode array: surgical and audiological outcomes.

PURPOSE: To compare the surgical and audiological outcomes with two perimodiolar electrode arrays (Nucleus 512-Contour Advance® y Nucleus 532-Slim Perimodiolar®) and a straight electrode array (Nucleus 422/522). METHODS: Patients were retrospectively selected from our cochlear implant program database. Only patients with a history of bilateral, sensorineural postlingually profound hearing loss who underwent cochlear implant surgery with either a N512, a N532 or a N422 were included. Throughout a year of follow-up, pure tone audiometry (PTA), speech perception, Impedances and T-C Thresholds levels were analyzed. Surgical data were also analyzed. RESULTS: 66 patients were included (19-CI532, 20-CI512 and 27-CI422). The most common type of cochlea access with the N532, N512 and N422 was through an extended round window, a promontorial cochleostomy and a pure round window, respectively. No significant differences were observed after 12 months in Mean PTA and Speech recognition. No significant differences were seen in the levels of hearing preservation at frequencies of 250 and 500. The average values of the impedances were significantly higher in the CI group N532 and N422 than in the N512. The mean values of the T and C levels were significantly lower in the CI groups N532 and N422 compared with the N512. CONCLUSIONS: No significant differences were observed after 12 months in Mean PTA and Speech recognition; however, a faster acquisition of auditory results were observed in the group of patients treated with the CI N532. The type of electrode array influences in the type of cochleostomy.

Preservation of residual hearing after cochlear implant surgery with slim modiolar electrode.

PURPOSE: To evaluate the insertion results and hearing preservation of a novel slim modiolar electrode (SME) in patients with residual hearing. METHODS: We retrospectively collected the data from the medical files of 17 patients (18 ears) implanted with a SME. All patients had functional low frequency hearing (PTA (0.125-0.5 kHz) ≤ 80 dB HL). The insertion results were re-examined from the postoperative cone-beam computed tomography scans. Postoperative thresholds were obtained at the time of switch-on of the sound processors (mean 43 days) and at latest follow-up (mean 582 days). The speech recognition in noise was measured with the Finnish matrix sentence test preoperatively and at follow-up. RESULTS: The mean insertion depth angle (IDA) was 395°. Neither scala dislocations nor tip fold over were detected. There were no total hearing losses. Functional low-frequency hearing was preserved in 15/18 (83%) ears at switch-on and in 14/17 (82%) ears at follow-up. According to HEARRING classification, 55% (10/18) had complete HP at switch-on and 41% (7/17) still at follow-up. Thirteen patients (14 ears) were initially fitted with electric-acoustic stimulation and seven patients (8 ears) continued to use it after follow-up. CONCLUSIONS: The preliminary hearing preservation results with the SME were more favorable than reported for other perimodiolar electrodes. The results show that the array may also be feasible for electro-acoustic stimulation; it is beneficial in that it provides adequate cochlear coverage for pure electrical stimulation in the event of postoperative or progressive hearing loss.

The Oticon Medical Neuro Zti cochlear implant and the Neuro 2 sound processor: multicentric evaluation of outcomes in adults and children.

Objective: This study evaluated the outcomes of the Oticon Medical Neuro Zti cochlear implant and the Neuro 2 sound processor.Design: Neuro One users were upgraded to Neuro 2. Monosyllabic word identification was evaluated in adults with Neuro One after ≥5 months, with Neuro 2 at upgrade, and with Neuro 2 after 3 months. Self-reported listening ability, satisfaction, and usability were measured in adults and children.Study sample: Participants were 44 adults and 26 children.Results: Speech identification scores in quiet and noise were 58% and 45% with Neuro One and 67% and 55% with Neuro 2 after 3 months, respectively. Hearing impairment duration and number of active electrodes significantly predicted speech identification in noise with Neuro 2. Significantly higher questionnaire ratings were obtained for Neuro 2 than Neuro One regarding listening ability in complex listening situations, comfort and music, as well as nine aspects of satisfaction and usability.Conclusion: This study demonstrates the clinical superiority of the Neuro 2 sound processor over Neuro One in terms of speech identification in quiet and in noise and reported patient benefit and satisfaction. Given the study design, sources of improvement may include factors unrelated to the sound processor itself.

Longitudinal effect of deactivating stimulation sites based on low-rate thresholds on speech recognition in cochlear implant users.

Objective: The objective of the current study was to examine the longitudinal effect of deactivating stimulation sites estimated to produce broad neural excitation on speech recognition. Design: Spatial patterns of neural excitation were estimated based on a previously established psychophysical measure, that is, detection threshold for low-rate pulse trains. Stimulation sites with relatively poor thresholds were deactivated in an experimental map. The acute effect was evaluated, in quiet and in noise, immediately after the experimental map was created (baseline), after the subjects practiced with the experimental map for two months (treatment), and after the subjects' daily map was switched back again to the clinical map for another two months (withdrawal). Study sample: Eight Cochlear Nucleus device users participated in the study. Results: For both listening in noise and in quiet, the greatest effect of deactivation was observed after the subjects were given time to adapt to the new frequency allocations. The effect was comparable for listening in fluctuating and steady-state noises. All subjects benefited from deactivation for listening in noise, but subjects with greater variability in thresholds were more likely to benefit from deactivation for listening in quiet. Conclusion: The benefit of electrode deactivation for speech recognition can increase with practice.

The influence of cochlear morphology on the final electrode array position.

OBJECTIVE: Preoperative information about cochlear morphology and size increasingly seems to be a defining factor of electrode choice in cochlear implant surgery. Different types of electrodes differ in length and diameter to accommodate individual cochlear anatomy. Smaller cochlear size results in increased insertion depth with a higher risk to dislocate and causes cochlear trauma with reduced postoperative outcome. The objective of the current study is to describe the three-dimensional size of the cochlea, to compare interindividual differences, to determine the relationship between cochlear size and insertion angle, and to define risk factors for dislocation during insertion. DESIGN: Four hundred and three patients implanted between 2003 and 2010 inserted via cochleostomy with a perimodiolar electrode array (Cochlear™ Contour Advance® electrode array) have been compared. CBCT (Cone beam computed tomography) was used to determine electrode array position (scala tympani versus scala vestibuli insertion, intracochlear dislocation, and insertion angle) and cochlear size (diameters and height). The trajectory of the electrode array and the lateral wall have been measured, and the position of the electrode array has been estimated. RESULTS: The mean value of the largest diameter was 9.95 mm and that of the perpendicular distance was 6.54 mm. There was a statistically significant correlation between those values. Mean height was 3.85 mm. The intracochlear relation of the electrode array and the modiolus showed a statistically significant relationship with the cochlear expanse. The electrode array was more likely to dislocate in cochleae with a smaller diameter and a lower height. Cochleae with insertions into scala vestibuli exhibited a smaller height compared to scala tympani insertions with statistical significance. CONCLUSION: Cochlear size and shape is variable, and the measured data of this study confirm the finding of other researchers. This study established two heights by two different planes to achieve a three-dimensional understanding of the cochlea. The electrode array was more likely to dislocate in cochleae with smaller diameter and smaller height. It can be assumed that the height established in this study seems to be a new preoperative parameter to underline the risk of scalar dislocation and not favored scala vestibuli insertion if using a cochleostomy approach. In conclusion, cochlear size, especially the height, is influencing the final position of the electrode array. Using preoperative scans of the cochlear diameters and cochlear height, a next step to custom-sized arrays is available.

On the accuracy of cochlear duct length measurement in computed tomographic images.

PURPOSE: Patient specific selection of cochlear implants would benefit from pre-operative knowledge of cochlear length. Several methods for its measurement or estimation have been described in literature. This study focused on the achievable accuracy in clinically available imaging. METHODS: Five simplified cochlea models milled into porcine bone were scanned in water using clinical cone beam computed tomography. Due to their well-known dimensions these phantoms served as gold standard for the length measurements. Each phantom was measured ten times using the custom software Comet. In addition, cochleae in ten image datasets taken indiscriminately from clinical routine were measured ten times each to test the precision under realistic conditions. The results were also compared to estimations based on the diameter of the basal turn (A value) as described in literature. RESULTS: Measurement accuracy of the phantoms' lengths was high (average error: - 0.2 mm; standard deviation: 0.3 mm). The pooled standard deviation for the measurements in clinical datasets was 0.6 mm. Errors resulted mainly from problems locating the helicotrema. The estimations differed on average - 1.7 to + 0.4 mm from the manual measurements and had standard deviations between 0.5 and 0.6 mm depending on the algorithm. CONCLUSIONS: The program Comet was successfully used to accurately measure the length of the cochlea models in clinically available imaging. The lower image quality of patient scans reduced the precision of the measurement. Estimations using the A value are a quicker alternative for averagely sized cochleae in cases where the lack of accuracy is tolerable.

Incomplete and false tract insertions in cochlear implantation: retrospective review of surgical and auditory outcomes.

OBJECTIVES: To evaluate incidence, demographics, surgical, and radiological correlates of incomplete and false tract electrode array insertions during cochlear implantation (CI). To evaluate outcomes in patients with incomplete electrode insertion (IEI). STUDY DESIGN: Retrospective analysis. SETTING: Otology and skull base center. PATIENTS AND METHODS: Charts of 18 patients (19 ears) with incomplete or false tract insertions of the electrode array were evaluated who underwent CI, with at least 1 year follow-up (from 470 cases). Demographic findings, etiologies, pre-operative radiologic findings, operative records, post-operative plain radiographic assessment for extent of electrode insertion, and switch-on mapping were evaluated. Audiological outcomes were evaluated using maximum and last recorded vowel, word, sentence, and comprehension scores for patients with IEI. RESULTS: Incidence of insertional abnormalities was 4.25% with 17 instances of incomplete and 2 cases of insertion into superior semicircular canal. Mean age and duration of deafness were 55.18 ± 4.62 and 22.12 ± 5.71 years. Etiologies in the IEI group were idiopathic, otosclerosis, meningitis, chronic otitis media (COM), temporal bone fractures, and Neurofibromatosis-2. 29.4% cases had cochlear luminal obstruction. Mean radiological and active electrophysiological length of insertion was 20.49 ± 0.66 and 19.49 ± 0.88 mm, respectively. No significant correlation was observed between audiological outcomes and insertional length except in time to achieve maximum word scores (p = 0.04). Age at implantation had significant correlations with last recorded word and comprehension scores at mean follow-up of 42.9 months, and with time to achieve maximum auditory scores. CONCLUSIONS: IEI during cochlear implantation using straight electrodes can occur with or without cochlear luminal obstruction. Age plays an important role in the auditory rehabilitation in this patient subset.

Better-ear glimpsing with symmetrically-placed interferers in bilateral cochlear implant users.

For a frontal target in spatially symmetrically placed interferers, normal hearing (NH) listeners can use "better-ear glimpsing" to select time-frequency segments with favorable signal-to-noise ratio in either ear. With an ideal monaural better-ear mask (IMBM) processing, some studies showed that NH listeners can reach similar performance as in the natural binaural listening condition, although interaural phase differences at low frequencies can further improve performance. In principle, bilateral cochlear implant (BiCI) listeners could use the same better-ear glimpsing, albeit without exploiting interaural phase differences. Speech reception thresholds of NH and BiCI listeners were measured in three interferers (speech-shaped stationary noise, nonsense speech, or single talker) either co-located with the target, symmetrically placed at ±60°, or independently presented to each ear, with and without IMBM processing. Furthermore, a bilateral noise vocoder based on the BiCI electrodogram was used in the same NH listeners. Headphone presentation and direct stimulation with head-related transfer functions for spatialization were used in NH and BiCI listeners, respectively. Compared to NH listeners, both NH listeners with vocoder and BiCI listeners showed strongly reduced binaural benefit from spatial separation. However, both groups greatly benefited from IMBM processing as part of the stimulation strategy.

Speech enhancement for cochlear implant recipients.

In this study, a single microphone speech enhancement algorithm is proposed to improve speech intelligibility for cochlear implant recipients. The proposed algorithm combines harmonic structure estimation with a subsequent statistical based speech enhancement stage. Traditional minimum mean square error (MMSE) based speech enhancement methods typically focus on statistical characteristics of the noise and track the noise variance along time dimension. The MMSE method is usually effective for stationary noise, but not as useful for non-stationary noise. To address both stationary and non-stationary noise, the current proposed method not only tracks noise over time, but also estimates the noise structure along the frequency dimension by exploiting the harmonic structure of the target speech. Next, the estimated noise is employed in the traditional MMSE framework for speech enhancement. To evaluate the proposed speech enhancement solution, a formal listener evaluation was performed with 6 cochlear implant recipients. The results suggest that a substantial improvement in speech intelligibility performance can be gained for cochlear implant recipients in noisy environments.