MRI surveillance after translabyrinthine vestibular schwannoma resection and cochlear implantation: is it feasible?

PURPOSE: Cochlear implantation in patients with vestibular schwannomas is of increasing importance and interest. Two remaining challenges are the assessment of conduction of the cochlear nerve and the possibility of postoperative surveillance with magnetic resonance imaging. The aim of the current study was to assess follow-up imaging and determine the visibility of the internal auditory canal after vestibular schwannoma resection and cochlear implantation as well as in patients with persistent vestibular schwannomas and cochlear implants in place. Visibility of the internal auditory canal, cerebellopontine angle, and labyrinth were evaluated and graded. METHODS: For this retrospective study, 15 MR examinations of 13 patients after translabyrinthine vestibular schwannoma resection and ipsilateral cochlear implantation were included. All patients had been implanted with an MED-EL cochlear implant. Magnetic resonance imaging was carried out on a 1.5T device. All patients were prepped according to the manufacturer's recommendations. RESULTS: All 15 examinations were carried out without any adverse event during imaging, such as pain, magnet dislocation, or malfunction. The internal auditory canal and the cerebellopontine angle were sufficiently visible in all cases to allow for vestibular schwannoma follow-up. CONCLUSION: Magnetic resonance imaging surveillance of the internal auditory canal following vestibular schwannoma resection and cochlear implantation is feasible and safe with modern implants with a 1.5T magnetic resonance imaging device using metal artifact reduction sequences. Necessary follow-up imaging should not be a contraindication for cochlear implantation in patients with vestibular schwannomas.

Investigation of inner ear drug delivery with a cochlear catheter in piglets as a representative model for human cochlear pharmacokinetics.

Hearing impairment is the most common sensory disorder in humans, and yet hardly any medications are licensed for the treatment of inner ear pathologies. Intricate pharmacokinetic examinations to better understand drug distribution within this complex organ could facilitate the development of novel therapeutics. For such translational research projects, animal models are indispensable, but differences in inner ear dimensions and other anatomical features complicate the transfer of experimental results to the clinic. The gap between rodents and humans may be bridged using larger animal models such as non-human primates. However, their use is challenging and impeded by administrative, regulatory, and financial hurdles. Other large animal models with more human-like inner ear dimensions are scarce. In this study, we analyzed the inner ears of piglets as a potential representative model for the human inner ear and established a surgical approach for intracochlear drug application and subsequent apical sampling. Further, controlled intracochlear delivery of fluorescein isothiocyanate-dextran (FITC-d) was carried out after the insertion of a novel, clinically applicable CE-marked cochlear catheter through the round window membrane. Two, six, and 24 hours after a single injection with this device, the intracochlear FITC-d distribution was determined in sequential perilymph samples. The fluorometrically assessed concentrations two hours after injection were compared to the FITC-d content in control groups, which either had been injected with a simple needle puncture through the round window membrane or the cochlear catheter in combination with a stapes vent hole. Our findings demonstrate not only significantly increased apical FITC-d concentrations when using the cochlear catheter but also higher total concentrations in all perilymph samples. Additionally, the concentration decreased after six and 24 hours and showed a more homogenous distribution compared to shorter observation times.

The Effect of Pulse Shape and Interphase Gaps on Speech Perception and Perceived Sound Quality in Electrical Hearing.

BACKGROUND: Stimulation with triphasic pulses has been shown to reduce the occurrence of unwanted facial nerve stimulation (FNS) with cochlear implants (CIs). However, there is little data available on how different pulse shapes affect the hearing outcome with electrical hearing in general. The aim of the study was to evaluate the effects of different stimulation pulse shapes on speech perception in noise, as well as loudness perception and subjective sound quality. METHODS: Twenty experienced cochlear-implant users not suffering from FNS participated in a prospective single-visit study. Based on the subjects' current clinical fitting, six fitting maps with different pulse shapes (biphasic and triphasic) and different interphase gap (IPG) durations (2.1 µs, 10 µs, and 20 µs) were created. First, the loudness was balanced for each configuration by adjusting the stimulation charge amount. Then, speech perception in noise was measured with a German matrix sentence test (Oldenburg Sentence test). The perception of particular sound attributes of speech and music, as well as overall preference, was evaluated with visual analog scales. RESULTS: Similar levels of speech perception were obtained with triphasic stimulation ( P = 0.891) and longer IPGs ( P = 0.361) compared to the subjects' clinical map settings. The stimulation amplitudes for equal loudness were significantly higher with triphasic stimulation compared to biphasic stimulation when keeping the IPG constant. Increasing the IPG had a significantly larger effect on perceived loudness ( P < 0.0001) and charge reduction for equal loudness with triphasic pulses compared to biphasic pulses. Triphasic configuration showed lower overall subjective sound quality ratings than biphasic for speech intelligibility, clarity, naturalness, and overall preference, as well as for music naturalness, and overall preference in the acute setting without adaptation time. Post-hoc pairwise comparisons against the clinical map revealed significantly lower speech naturalness ratings for triphasic with 2.1 µs IPG and for triphasic with 20 µs IPG only. CONCLUSION: Although some sound quality attributes were rated lower compared to the clinical map in the acute test setting, stimulation with triphasic pulses does not affect speech perception in noise and can be considered as a valuable option in CI fitting.

The Functional Hearing Gain with an Active Transcutaneous Bone Conduction Implant Does Not Correlate with the Subjective Hearing Performance.

The functional hearing outcome with hearing implants does not always properly reflect the subjective benefit in everyday listening situations. In this study, the functional hearing gain and the impact on the subjective hearing ability and quality of life were assessed in patients with a Bonebridge. A chart review was performed on 45 patients with a Bonebridge who were provided with questionnaires regarding the hearing quality and health-related quality of life during their last clinical visit. The questionnaires consisted of the Speech, Spatial and Qualities (SSQ) and the Health Utility Index Mark 3 (HUI3). Eleven patients had to be excluded due to missing data. A total of 34 patients (37 ears) were included in the study. Aided hearing thresholds were significantly lower compared with the unaided condition, with a mean functional gain of 26.87 dB for patients with mixed/conductive hearing loss (MHL/CHL). Although patients with single-sided deafness (SSD) scored slightly lower on the SSQ compared with patients with MHL/CHL, all included patients reported improved subjective hearing quality with the BB compared with the hearing situation before implantation. No correlation was found between the functional hearing gain and the subdomains of the SSQ. SSD patients scored the HUI3 subdomain "hearing" slightly lower compared with MHL/CHL patients. Although not significant, a relationship was found between the functional gain and the "hearing" subdomain. No correlation was found for the other subdomains of the HUI3. Audiological measurements showed significantly improved hearing thresholds with the Bonebridge. Most importantly, the subjective benefit achieved in everyday listening situations was superior compared with the previous hearing condition. The lack of correlation between subjective questionnaire results and the functional hearing gain shows the importance of assessing both audiological and subjective hearing quality parameters in clinical routine.

Robotic Cochlear Implant Surgery: Imaging-Based Evaluation of Feasibility in Clinical Routine.

Background: Robotic surgery has been proposed in various surgical fields to reduce recovery time, scarring, and to improve patients' outcomes. Such innovations are ever-growing and have now reached the field of cochlear implantation. To implement robotic ear surgery in routine, it is of interest if preoperative planning of a safe trajectory to the middle ear is possible with clinically available image data. Methods: We evaluated the feasibility of robotic cochlear implant surgery in 50 patients (100 ears) scheduled for routine cochlear implant procedures based on clinically available imaging. The primary objective was to assess if available high-resolution computed tomography or cone beam tomography imaging is sufficient for planning a trajectory by an otological software. Secondary objectives were to assess the feasibility of cochlear implant surgery with a drill bit diameter of 1.8 mm, which is the currently used as a standard drill bit. Furthermore, it was evaluated if feasibility of robotic surgery could be increased when using smaller drill bit sizes. Cochlear and trajectory parameters of successfully planned ears were collected. Measurements were carried out by two observers and the interrater reliability was assessed using Cohen's Kappa. Results: Under the prerequisite of the available image data being sufficient for the planning of the procedure, up to two thirds of ears were eligible for robotic cochlear implant surgery with the standard drill bit size of 1.8 mm. The main reason for inability to plan the keyhole access was insufficient image resolution causing anatomical landmarks not being accurately identified. Although currently not applicable in robotic cochlear implantation, narrower drill bit sizes ranging from 1.0 to 1.7 mm in diameter could increase feasibility up to 100%. The interrater agreement between the two observers was good for this data set. Discussion: For robotic cochlear implant surgery, imaging with sufficient resolution is essential for preoperative assessment. A slice thickness of <0.3 mm is necessary for trajectory planning. This can be achieved by using digital volume tomography while radiation exposure can be kept to a minimum. Furthermore, surgeons who use the software tool, should be trained on a regular basis in order to achieve planning consistency.

Safety and Efficacy of Implantation of the Bonebridge Active Transcutaneous Bone-Conduction Device Using Implant Lifts.

BACKGROUND: Implant lifts were recently introduced to facilitate implantation of the Bonebridge and to reduce the risk of uncovering the sigmoid sinus and/or dura. PURPOSE: The current study analyzed medical, technical, and audiological outcomes of implantation with the Bonebridge implant using lifts. RESEARCH DESIGN: This was a retrospective study on all consecutive patients implanted with a bone-conduction hearing implant at a tertiary medical referral center between March 2012 and October 2018. Outcome measures were complications, explantations, and revisions and the mean time of implant use. Audiological results were assessed as well. Outcomes were evaluated for devices implanted with BCI Lifts and compared with those implanted without lifts. RESULTS: In the study period, 13 out of a total of 54 implantations were conducted using one or two 1- to 4-mm BCI Lifts. During the follow-up period, two complications occurred and both in patients implanted without lifts (2/41; 4.9%). All patients in the lifts group were using the implant at the end of observation period. No statistically significant difference was observed in functional hearing gain or word-recognition improvement at 65 dB between two groups. CONCLUSIONS: The use of BCI Lifts in Bonebridge implantations was not associated with adverse events during the observation period. The clinical follow-up revealed no complications in implantations requiring lifts. Furthermore, the functional hearing gain and the word-recognition improvement did not differ from those of devices implanted without lifts. Data indicate safety and efficacy for Bonebridge implantations using lifts.

Is otologic surgery contributing to the opioid epidemic?

BACKGROUND: The opioid epidemic is a significant public health crisis challenging the lives of North Americans. Interestingly, this problem does not exist to the same extent in Europe. Surgeons play a significant role in prescribing opioids, especially in the context of post-operative pain management. The aim of this study was to compare the post-surgical prescribing patterns of otologists comparing Canada and Austria. METHODS: An online questionnaire was sent to 33 Canadian and 32 Austrian surgeons, who perform otologic surgery on a regular basis. Surgeons were asked to answer some questions about their background as well as typical prescribing patterns for postoperative pain medication for different ear surgeries (cochlear implant, stapedotomy, tympanoplasty). In addition, surgeons were asked about the typical use of local anesthetics for pain control at the end of a procedure. Otologists gave an estimate how confident they were that their therapy and prescriptions provide sufficient pain control to their patients. RESULTS: Analysis of the returned questionnaires showed that opioids are more commonly prescribed in Canada than in Austria. Nonsteroidal anti-inflammatory drugs are used for postoperative pain more regularly after ear surgery in Austria, as opposed to Canada. Some of the prescribed drugs by European otologists are not available in North America. The use of local anesthetics at the end of surgery is not common in Austria. Surgeons´ confidence that the prescribed pain medication was sufficient to control postoperative symptoms was higher in the group not prescribing opioids than in the group that did routinely prescribe opioids. CONCLUSION: Prescribing patterns differ substantially between the two evaluated countries. This data suggests an opportunity to reduce opioid prescriptions after otologic surgeries. Studies to evaluate pain after these operations as well as efficacy of analgesics following ear surgery are an important next step.

Long-Term, Multicenter Results With the First Transcutaneous Bone Conduction Implant.

OBJECTIVE: Investigation of long-term safety and performance of an active, transcutaneous bone conduction implant in adults and children up to 36 months post-implantation. STUDY DESIGN: Prospective, single-subject repeated-measures design. SETTING: Otolaryngology departments of eight German and Austrian hospitals.∗†‡§||¶#∗∗†† Affiliations listed above that did not participate in the study.‡‡§§||||¶¶. PATIENTS: Fifty seven German-speaking patients (49 adults and eight children) suffering from conductive or mixed hearing loss, with an upper bone conduction threshold limit of 45 dB HL at frequencies between 500 and 3000 Hz. INTERVENTION: Implantation of the Bonebridge transcutaneous bone conduction hearing implant (tBCI). MAIN OUTCOME MEASURES: Patients' audiometric pure tone averages (PTA4) (0.5, 1, 2, 4 kHz) thresholds (air conduction, bone conduction, and sound field) and speech perception (word recognition scores [WRS] and speech reception thresholds [SRT50%]) were tested preoperatively and up to 36 months postoperatively. Patients were also monitored for adverse events and administered quality-of-life questionnaires. RESULTS: Speech perception (WRS: pre-op: 17.60%, initial activation [IA]: 74.23%, 3M: 83.65%, 12M: 83.46%, 24M: 84.23%, 36M: 84.42%; SRT50%: pre-op: 65.56 dB SPL, IA: 47.67 dB SPL, 3M: 42.61 dB SPL, 12M: 41.11 dB SPL, 24M: 41.74 dB SPL, 36M: 42.43 dB SPL) and sound field thresholds (pre-op: 57.66 dB HL, IA: 33.82 dB HL, 3M: 29.86 dB HL, 12M: 28.40 dB HL, 24M: 28.22 dB HL, 36M: 28.52 dB HL) improved significantly at all aided postoperative visits. Air and bone conduction thresholds showed no significant changes, confirming preservation of patients' residual unaided hearing. All adverse events were resolved by the end of the study. CONCLUSIONS: Safety and performance of the tBCI was demonstrated in children and adults 36 months postoperatively.

Performance With an Adhesive Bone Conduction Device in Active Transcutaneous Bone Conduction Implant Users.

OBJECTIVES: The aim of this study was to evaluate the performance and limits of an adhesive bone conduction hearing aid in patients implanted with an active transcutaneous bone conduction implant. Therefore, hearing performance and subjective benefit of patients with mixed and conductive hearing loss were assessed with both bone conduction devices. STUDY DESIGN AND PATIENTS: This cohort study was conducted at a tertiary care center. Fifteen subjects, who had been implanted with an active transcutaneous device previously, were included and used the adhesive hearing device for 3 weeks instead of the implant. Subjects underwent two sets of audiological tests as well as assessments of quality of life at the beginning and at the end of the testing period. RESULTS: Audiological results showed a significantly greater improvement in regards to functional hearing gain and word recognition scores with the transcutaneous bone conduction device than the nonimplantable adhesive device. Regression analysis showed a trend toward greater improvement with the transcutaneous device compared with the adhesive device in patients with an increasing bone conduction threshold. Hearing-specific and general quality-of-life questionnaires revealed no significant difference between the two devices. CONCLUSION: Patients with mixed or conductive hearing loss experience hearing gain with both, the adhesive device and the active transcutaneous device. The adhesive device may be a valuable alternative to the active transcutaneous device, depending on the individual bone conduction threshold.

Speech Segregation in Active Middle Ear Stimulation: Masking Release With Changing Fundamental Frequency.

OBJECTIVES: Temporal fine structure information such as low-frequency sounds including the fundamental frequency (F0) is important to separate different talkers in noisy environments. Speech perception in noise is negatively affected by reduced temporal fine structure resolution in cochlear hearing loss. It has been shown that normal-hearing (NH) people as well as cochlear implant patients with preserved acoustic low-frequency hearing benefit from different F0 between concurrent talkers. Though patients with an active middle ear implant (AMEI) report better sound quality compared with hearing aids, they often struggle when listening in noise. The primary objective was to evaluate whether or not patients with a Vibrant Soundbridge AMEI were able to benefit from F0 differences in a concurrent talker situation and if the effect was comparable to NH individuals. DESIGN: A total of 13 AMEI listeners and 13 NH individuals were included. A modified variant of the Oldenburg sentence test was used to emulate a concurrent talker scenario. One sentence from the test corpus served as the masker and the remaining sentences as target speech. The F0 of the masker sentence was shifted upward by 4, 8, and 12 semitones. The target and masker sentences were presented simultaneously to the study subjects and the speech reception threshold was assessed by adaptively varying the masker level. To evaluate any impact of the occlusion effect on speech perception, AMEI listeners were tested in two configurations: with a plugged ear-canal contralateral to the implant side, indicated as AMEIcontra, or with both ears plugged, indicated as AMEIboth. RESULTS: In both study groups, speech perception improved when the F0 difference between target and masker increased. This was significant when the difference was at least 8 semitones; the F0-based release from masking was 3.0 dB in AMEIcontra (p = 0.009) and 2.9 dB in AMEIboth (p = 0.015), compared with 5.6 dB in NH listeners (p < 0.001). A difference of 12 semitones revealed a F0-based release from masking of 3.5 dB in the AMEIcontra (p = 0.002) and 3.4 dB in the AMEIboth (p = 0.003) condition, compared with 5.0 dB in NH individuals (p < 0.001). CONCLUSIONS: Though AMEI users deal with problems resulting from cochlear damage, hearing amplification with the implant enables a masking release based on F0 differences when F0 between a target and masker sentence was at least 8 semitones. Additional occlusion of the ear canal on the implant side did not affect speech performance. The current results complement the knowledge about the benefit of F0 within the acoustic low-frequency hearing.

A Randomized Cross-over Trial Comparing a Pressure-free, Adhesive to a Conventional Bone Conduction Hearing Device.

OBJECTIVES: The main aim of this study was to compare the average daily wearing time of a conventional bone conduction device with a pressure-free, adhesive bone conduction device. Further, audiologic and quality-of-life outcome parameters were evaluated. METHODS: An academic, prospective, randomized cross-over trial was performed at a single center.Thirteen subjects between 12 and 63 years with conductive hearing loss were included.Average daily wearing time and subjective observations were assessed in a diary. Sound field audiometry, Freiburg monosyllables word test, and Oldenburg sentence test in quiet and in noise were carried out after 2 weeks of habituation to each device. AQoL-8D and SSQ-12 questionnaires were completed at baseline and after a 2-week test interval. RESULTS: Median wearing time of the devices was 8.1 hours (5.8-10.2 interquartile range) for the adhesive and 4.3 hours (2.7-7.1) for the conventional bone conduction device, the difference was statistically significant (p = 0.033). There were no statistically significant differences in sound field audiometry, Freiburg monosyllables word test, and Oldenburg sentence test when comparing the two devices. AQoL-8D and SSQ-12 showed a significant improvement with the devices in comparison with baseline, with no significant difference between devices in the total scores. Ten subjects reported pain using the conventional device, two subjects reported skin irritations using the adhesive device. CONCLUSION: For patients with mixed or conductive hearing loss, the adhesive device is a valuable alternative with a significantly longer daily wearing time.

Single Sided Deaf Cochlear Implant Users in the Difficult Listening Situation: Speech Perception and Subjective Benefit.

OBJECTIVES: Patients with single-sided deafness (SSD) have great difficulties in listening situations which rely on binaural auditory processing. The purpose of this study was to examine to which extent a cochlear implant (CI) can improve speech perception outcomes in various noisy listening environments. Additionally, the ability to use interaural level differences for sound localization and subjective benefit with the CI were assessed. METHODS: Ten single-sided deaf patients with CI were tested in different loudspeaker configurations with and without the CI. A multi-source noise field (MSNF) with uncorrelated noise from four different directions was used in addition to a setup with the signal from the CI side and noise from the normal-hearing side (SCINNH, azimuth of ±45 degrees). Ten normal-hearing subjects were used as a control for the setup. Speech understanding was measured by an adaptive sentence test (Oldenburg Sentence Test, OLSA) in stationary speech shaped noise and temporally modulated noise to assess the benefit in each listening situation. Sensitivity to interaural level differences was measured in a lateralization experiment. Furthermore, patients completed the Bern Benefit in Single-Sided Deafness (BBSS) questionnaire to assess subjective benefit with the CI. RESULTS: An overall average benefit in speech reception threshold (SRT) of 1.6 dB (±0.6 dB standard error of the mean [SEM]) was observed in the binaural listening condition (with CI) in all conditions. In the MSNF setup thresholds improved by 0.4 dB (±0.5 dB SEM) and in the SCINNH configuration by 2.7 dB (±0.7 dB SEM). The choice of masking noise effect also had a significant effect on the SRT outcome. The lateralization performance of the SSD users was on a par with the normal hearing group. BBSS scores reflect the overall benefit with the CI apparent in the speech test results. CONCLUSION: Patients with single-sided deafness do benefit from a CI in difficult listening environments and are able to localize sound based on interaural level differences. Considering these outcomes, cochlear implantation represents a promising treatment option for patients with single-sided deafness.

First Results With a New, Pressure-free, Adhesive Bone Conduction Hearing Aid.

OBJECTIVES: The aim of this study was to evaluate the hearing benefit, advantages, and disadvantages in a series of patients using a new, nonimplantable, pressure-free, adhesive bone conduction hearing aid. METHODS: Twelve patients were included in the study at the ear, nose, and throat department of the Medical University of Vienna. All patients suffered from conductive hearing loss for at least 3 months. A sound field audiometry, Freiburg monosyllables word test and Oldenburg sentence test were carried out. Additionally, sound quality (SSQ12) and quality of life (AQoL-8D) were assessed using questionnaires. RESULTS: Analysis revealed an average aided threshold of 30.8 dB HL (±7.1 SD) and an unaided threshold of 45.1 dB HL (±7.0 SD), resulting in a statistically significant (p < 0.001) average functional gain. Additionally, participants experienced about 30% gain in word recognition scores at 65 dB sound pressure level, speech reception threshold in quiet was 56.8 dB (±6.1) and improved to 44.5 dB (±6.4) in the aided condition. Both, the SSQ12 and the AQoL-8D showed a statistically significant improvement when comparing the scores at the beginning of the study to the answers after 2 weeks of device usage (SSQ12 (p < 0.002) and AQoL-8D (p = 0.002)). Neither skin irritations nor pain were reported during the study period. CONCLUSION: In conclusion, this new, adhesive bone conduction hearing aid has a high patient satisfaction rate while causing no skin irritation or pain.

Fixed and adaptive beamforming improves speech perception in noise in cochlear implant recipients equipped with the MED-EL SONNET audio processor.

OBJECTIVE: To determine the impact of the fixed and adaptive beamforming technology of the new MED-EL SONNET cochlear implant audio processor on speech perception in noise. METHODS: The study cohort comprises 18 postlingually deafened adult cochlear implant recipients with at least six months of experience. Speech reception thresholds were measured with the Oldenburg Sentence Test in continuous, speech-shaped noise. Target sentences were presented in front of the listener, with noise sources placed at -135° and 135°, respectively. Outcome measures were the differences in speech reception threshold using omnidirectional, fixed and adaptive beamformer microphone settings. RESULTS: The use of directional microphones significantly improved speech reception thresholds: fixed beamformer vs. omnidirectional: 4.3 dB (95%-CI [3.1; 5.5]), p<0.0001; adaptive beamformer vs. omnidirectional: 6.1 dB (95%-CI [4.9; 7.3]), p<0.0001; and adaptive beamformer vs. fixed beamformer: 1.8 dB (95%-CI [0.7; 3.0]), p = 0.001. CONCLUSION: This study confirms the previously reported improvements in speech perception in noise of the fixed beamformer microphone setting and is the first to report significant improvements in speech perception in noise when applying the adaptive beamformer microphone settings of the SONNET audio processor. Cochlear implant users may be able to benefit from improved hearing performance especially in difficult listening situations.

Masking release with changing fundamental frequency: Electric acoustic stimulation resembles normal hearing subjects.

It has been shown that patients with electric acoustic stimulation (EAS) perform better in noisy environments than patients with a cochlear implant (CI). One reason for this could be the preserved access to acoustic low-frequency cues including the fundamental frequency (F0). Therefore, our primary aim was to investigate whether users of EAS experience a release from masking with increasing F0 difference between target talker and masking talker. The study comprised 29 patients and consisted of three groups of subjects: EAS users, CI users and normal-hearing listeners (NH). All CI and EAS users were implanted with a MED-EL cochlear implant and had at least 12 months of experience with the implant. Speech perception was assessed with the Oldenburg sentence test (OlSa) using one sentence from the test corpus as speech masker. The F0 in this masking sentence was shifted upwards by 4, 8, or 12 semitones. For each of these masker conditions the speech reception threshold (SRT) was assessed by adaptively varying the masker level while presenting the target sentences at a fixed level. A statistically significant improvement in speech perception was found for increasing difference in F0 between target sentence and masker sentence in EAS users (p = 0.038) and in NH listeners (p = 0.003). In CI users (classic CI or EAS users with electrical stimulation only) speech perception was independent from differences in F0 between target and masker. A release from masking with increasing difference in F0 between target and masking speech was only observed in listeners and configurations in which the low-frequency region was presented acoustically. Thus, the speech information contained in the low frequencies seems to be crucial for allowing listeners to separate multiple sources. By combining acoustic and electric information, EAS users even manage tasks as complicated as segregating the audio streams from multiple talkers. Preserving the natural code, like fine-structure cues in the low-frequency region, seems to be crucial to provide CI users with the best benefit.

Sound Localization in Patients With Congenital Unilateral Conductive Hearing Loss With a Transcutaneous Bone Conduction Implant.

OBJECTIVE: There is no consensus regarding the benefit of implantable hearing aids in congenital unilateral conductive hearing loss (UCHL). This study aimed to measure sound source localization performance in patients with congenital UCHL and contralateral normal hearing who received a new bone conduction implant. STUDY DESIGN: Evaluation of within-subject performance differences for sound source localization in a horizontal plane. SETTING: Tertiary referral center. PATIENTS: Five patients with atresia of the external auditory canal and contralateral normal hearing implanted with transcutaneous bone conduction implant at the Medical University of Vienna were tested. INTERVENTION: Activated/deactivated implant. MAIN OUTCOME MEASURE: Sound source localization test; localization performance quantified using the root mean square (RMS) error. RESULTS: Sound source localization ability was highly variable among individual subjects, with RMS errors ranging from 21 to 40 degrees. Horizontal plane localization performance in aided conditions showed statistically significant improvement compared with the unaided conditions, with RMS errors ranging from 17 to 27 degrees. The mean RMS error decreased by a factor of 0.71 (p < 0.001). CONCLUSION: Analysis revealed improved sound localization performance in a horizontal plane with the activated transcutaneous bone conduction implant. Some patients with congenital UCHL might be capable of developing improved horizontal plane localization abilities with the binaural cues provided by this device.