Single-sided Deafness Patients Research Articles

CI in single-sided deafness

The cochlear implant (CI) as a treatment option for single-sided deafness (SSD) started with a clinical study looking in to the influence of cochlear implantation with a MED-EL device on incapacitating unilateral tinnitus in SSD. The study began in 2003 and was conducted by P. Van de Heyning and his team in Antwerp, Belgium. The first CI in SSD without tinnitus in Germany was implanted by J. Mueller and R. Jacob in Koblenz in 2005. Translational research activities took place since then to evaluate the CI as a treatment option for SSD not only in adults but also in children. They assessed the hearing performance of SSD patients implanted with CI, importance of long electrode arrays in SSD patients, degree of acceptance of CI by SSD children, importance of early CI implantation in SSD children in developing language skills, music enjoyment by hearing with two ears and evidence on spiral ganglion cell body distribution. In 2013, MED-EL was the first CI manufacturer to receive the CE mark for the indication of SSD and asymmetric hearing loss (AHL) in adults and children. In 2019, MED-EL was the first CI manufacturer to get its CI device approved for patients over the age of five with SSD and AHL, by the FDA in the USA. This article covers the milestones of translational research from the first concept to the widespread clinical use of CI in SSD.

Cochlear Implantation and Other Treatments in Single-Sided Deafness and Asymmetric Hearing Loss: Results of a National Multicenter Study Including a Randomized Controlled Trial

Introduction: Cochlear implantation is a recent approach proposed to treat single-sided deafness (SSD) and asymmetric hearing loss (AHL). Several cohort studies showed its effectiveness on tinnitus and variable results on binaural hearing. The main objective of this study is to assess the outcomes of cochlear implantation and other treatment options in SSD/AHL on quality of life. Methods: This prospective multicenter study was conducted in 7 tertiary university hospitals and included an observational cohort study of SSD/AHL adult patients treated using contralateral routing of the signal (CROS) hearing aids or bone-anchored hearing systems (BAHSs) or who declined all treatments, and a randomized controlled trial in subjects treated by cochlear implantation, after failure of CROS and BAHS trials. In total, 155 subjects with SSD or AHL, with or without associated tinnitus, were enrolled. After 2 consecutive trials with CROS hearing aids and BAHSs on headband, all subjects chose any of the 4 treatment options (abstention, CROS, BAHS, or cochlear implant [CI]). The subjects who opted for a CI were randomized between 2 arms (CI vs. initial observation). Six months after the treatment choice, quality of life was assessed using both generic (EuroQoL-5D, EQ-5D) and auditory-specific quality-of-life indices (Nijmegen Cochlear implant Questionnaire [NCIQ] and Visual Analogue Scale [VAS] for tinnitus severity). Performances for speech-in-noise recognition and localization were measured as secondary outcomes. Results: CROS was chosen by 75 subjects, while 51 opted for cochlear implantation, 18 for BAHSs, and 11 for abstention. Six months after treatment, both EQ-5D VAS and auditory-specific quality-of-life indices were significantly better in the “CI” arm versus “observation” arm. The mean effect of the CI was particularly significant in subjects with associated severe tinnitus (mean improvement of 20.7 points ± 19.7 on EQ-5D VAS, 20.4 ± 12.4 on NCIQ, and 51.4 ± 35.4 on tinnitus). No significant effect of the CI was found on binaural hearing results. Before/after comparisons showed that the CROS and BAHS also improved significantly NCIQ scores (for CROS: +7.7, 95% confidence interval [95% CI] = [4.5; 10.8]; for the BAHS: +14.3, 95% CI = [7.9; 20.7]). Conclusion: Cochlear implantation leads to significant improvements in quality of life in SSD and AHL patients, particularly in subjects with associated severe tinnitus, who are thereby the best candidates to an extension of CI indications.

Cost Effectiveness of Cochlear Implantation in Single-Sided Deafness.

To analyze the cost effectiveness of cochlear implantation (CI) for the treatment of single-sided deafness (SSD). Cost-utility analysis in an adapted Markov model. Adults with single-sided deafness in a high-income country. Unilateral CI was compared with no intervention. Incremental cost-effectiveness ratios were compared with different cost-effectiveness thresholds ($10,000 to $150,000) for different age, sex, and cost combinations. The calculations were based on the quality-adjusted life year (QALY), national life expectancy tables, and different cost settings. The health utility values for the QALY were either directly collected from published data, or, derived from published data using a regression model of multiple utility indices (regression estimate). The regression estimate showed an increase of the health utility value from 0.62 to 0.74 for SSD patients who underwent CI. CI for SSD was cost effective for women up to 64 years ($50,000 per-QALY threshold), 80 years ($100,000 per-QALY threshold), and 86 years ($150,000 per-QALY threshold). For men, these values were 58, 77, and 84, respectively. Changing the discount rate by up to 5% further increased the cutoff ages up to 5 years. A detailed cost and age sensitivity analysis is presented and allows testing for cost effectiveness in local settings worldwide. CI is a cost-effective option to treat patients with SSD.

What is the Right Treatment for Adults With Unilateral Deafness?

What is the Right Treatment for Adults With Unilateral Deafness?

Cost-utility Analysis of Cochlear Implantation in Adults With Single-sided Deafness: Austrian and German Perspective.

Single-sided deafness (SSD) is associated with a loss of binaural hearing. Major limitations of such patients are poor speech understanding in noisy environments and a lack of spatial hearing. To date, cochlear implantation is the most promising approach to overcome these deficits in this group of patients. Cost-effectiveness analyses of cochlear implantation in patients with unilateral deafness. The model targets Austrian and German SSD patients who can either opt for treatment with a cochlear implant (CI) or decide against a CI and stay without any treatment. A Markov model analyzed as microsimulation was developed using TreeAge Pro 2019 software. Pre- and postoperative utility values generated with HUI-3 were used to populate the model. Costs covered by the national insurance were considered. Costs and utilities were discounted by 3%. A model time horizon of 20 years was set. According to Austrian base-case analysis, the incremental cost-utility ratio (ICUR) was €34845.2 per quality-adjusted life year gained when comparing the "CI strategy" to the "no treatment strategy." The ICUR is marginally lower when adapting a German cost perspective-it was €31601.25 per quality-adjusted life year gained. Sensitivity analyses showed that the cost-effectiveness results are stable. Analyses also showed that the longer the time horizon is set, the more favorable the cost-effectiveness result is. Based on currently available data, the Markov microsimulation model suggests that cochlear implantation is cost-effective in Austrian and German patients with SSD if no other treatment option is considered within the model.

Cochlear Implantation in Adults With Single-sided Deafness: Outcomes and Device Use.

To describe our experience with adults undergoing cochlear implantation (CI) for treatment of single-sided deafness (SSD). Retrospective case review. Tertiary referral center. Fifty-three adults with SSD. Unilateral CI. Speech perception testing in quiet and noise, tinnitus suppression, and device usage from datalogs. The mean age at CI was 53.2 years (SD 11.9). The mean duration of deafness was 4.0 years (SD 7.8). The most common etiology was idiopathic sudden SNHL (50%). Word recognition improved from 8.7% (SD 15) preoperatively to 61.8% (SD 20) at a mean follow-up of 3.3 years (SD 1.8) (p < 0.0001). Adaptive speech recognition testing in the "binaural with CI" condition (speech directed toward the front and noise toward the normal hearing ear) revealed a significant improvement by 2.6-dB SNR compared to the preoperative unaided condition (p = 0.0002) and by 3.6-dB SNR compared to when a device to route sound to the contralateral side was used (p < 0.0001). Tinnitus suppression was reported to be complete in 23 patients (43%) and improved in 20 patients (38%) while the device was on. The addition of the CI did not lead to a decrement in hearing performance in any spatial configuration. Device usage averaged 8.7 (SD 3.7) hours/day. Cochlear implantation in adult SSD patients can suppress tinnitus and achieve speech perception outcomes comparable with CI in conventional candidates. Modest improvements in spatial hearing were also observed and primarily attributable to the head shadow effect. Careful patient selection and counseling regarding potential benefits are important to optimize outcomes.

Current Perspectives in Management of Unilateral Sensorineural Hearing Loss and Single Sided Deafness

Unilateral Sensorineural Hearing Loss (USNHL) or even Single Sided Deafness (SSD) were mistakenly believed in the past that they could not induce a notable negative effect on the average individual adult. Respectively, a child with USNHL could eventually develop typically and adequately with no particular challenges. Today, it is well established that both children and adults with USNHL and SSD experience difficulties locating sound sources than their normal peers attributable to the concomitant deprivation of data utilized for localization; interaural time differences along with interaural intensity differences, especially for high frequency sounds. Moreover, USNHL and SSD patients suffer from the absence of the binaural benefits that permit people with bilateral Normal Hearing (NH) to perform relatively well in challenging listening environments. These benefits encompass binaural summation that causes improved speech perception, and binaural release from masking that facilitates word recognition in noise. Rising treatment strategies, involving various type of amplification, Assistive Listening Devices (ALSs) and Cochlear Implantation, can greatly widen our overall approach regarding USNHL and / or SSD. Nevertheless, most recent evidence points out that both prompt and adequate intervention is crucial to promote optimal outcomes.

Effects of Head Movements on Sound-Source Localization in Single-Sided Deaf Patients With Their Cochlear Implant On Versus Off.

We investigated the ability of single-sided deaf listeners implanted with a cochlear implant (SSD-CI) to (1) determine the front-back and left-right location of sound sources presented from loudspeakers surrounding the listener and (2) use small head rotations to further improve their localization performance. The resulting behavioral data were used for further analyses investigating the value of so-called "monaural" spectral shape cues for front-back sound source localization. Eight SSD-CI patients were tested with their cochlear implant (CI) on and off. Eight normal-hearing (NH) listeners, with one ear plugged during the experiment, and another group of eight NH listeners, with neither ear plugged, were also tested. Gaussian noises of 3-sec duration were band-pass filtered to 2-8 kHz and presented from 1 of 6 loudspeakers surrounding the listener, spaced 60° apart. Perceived sound source localization was tested under conditions where the patients faced forward with the head stationary, and under conditions where they rotated their heads between (Equation is included in full-text article.). (1) Under stationary listener conditions, unilaterally-plugged NH listeners and SSD-CI listeners (with their CIs both on and off) were nearly at chance in determining the front-back location of high-frequency sound sources. (2) Allowing rotational head movements improved performance in both the front-back and left-right dimensions for all listeners. (3) For SSD-CI patients with their CI turned off, head rotations substantially reduced front-back reversals, and the combination of turning on the CI with head rotations led to near-perfect resolution of front-back sound source location. (4) Turning on the CI also improved left-right localization performance. (5) As expected, NH listeners with both ears unplugged localized to the correct front-back and left-right hemifields both with and without head movements. Although SSD-CI listeners demonstrate a relatively poor ability to distinguish the front-back location of sound sources when their head is stationary, their performance is substantially improved with head movements. Most of this improvement occurs when the CI is off, suggesting that the NH ear does most of the "work" in this regard, though some additional gain is introduced with turning the CI on. During head turns, these listeners appear to primarily rely on comparing changes in head position to changes in monaural level cues produced by the direction-dependent attenuation of high-frequency sounds that result from acoustic head shadowing. In this way, SSD-CI listeners overcome limitations to the reliability of monaural spectral and level cues under stationary conditions. SSD-CI listeners may have learned, through chronic monaural experience before CI implantation, or with the relatively impoverished spatial cues provided by their CI-implanted ear, to exploit the monaural level cue. Unilaterally-plugged NH listeners were also able to use this cue during the experiment to realize approximately the same magnitude of benefit from head turns just minutes after plugging, though their performance was less accurate than that of the SSD-CI listeners, both with and without their CI turned on.

Is the cochlear implant a successful long-term solution for single-sided deaf and asymmetric hearing-impaired patients?

PurposeWe investigated the long-term results of cochlear implant (CI) recipients with asymmetric hearing loss (AHL) or single-sided deafness (SSD). We focused on wearing behavior, audiometric hearing rehabilitation, and subjective benefits of the CI. CI is expected to improve audiological results, subjective hearing perception, and tinnitus burden.MethodsSpeech recognition in background noise and sound localization were assessed preoperatively and after at least six years of CI experience. Validated questionnaires determined the subjective benefit of CI use and the subjective evaluation of tinnitus.ResultsOver 80% of the included AHL and SSD CI recipients used their CI between 6 and 10 h daily; four subjects with SSD were non-users. Speech recognition in background noise and sound localization improved significantly compared with the unaided preoperative situation. Additionally, CI improved subjective speech intelligibility and spatial hearing impression while reducing tinnitus burden.ConclusionSubjects with AHL and SSD benefit from CI, subjectively and audiologically. Cochlear implant is a successful long-term treatment for AHL and SSD.

Development of cortical auditory responses to speech in noise in unilaterally deaf adults following cochlear implantation.

BackgroundFor patients with single-sided deafness (SSD), restoration of binaural function via cochlear implant (CI) has been shown to improve speech understanding in noise. The objective of this study was to investigate changes in behavioral performance and cortical auditory responses following cochlear implantation.DesignProspective longitudinal study.SettingTertiary referral center.MethodsSix adults with SSD were tested before and 12 months post-activation of the CI. Six normal hearing (NH) participants served as experimental controls. Speech understanding in noise was evaluated for various spatial conditions. Cortical auditory evoked potentials were recorded with /ba/ stimuli in quiet and in noise. Global field power and responses at Cz were analyzed.ResultsSpeech understanding in noise significantly improved with the CI when speech was presented to the CI ear and noise to the normal ear (p<0.05), but remained poorer than that of NH controls (p<0.05). N1 peak amplitude measure in noise significantly increased after CI activation (p<0.05), but remained lower than that of NH controls (p<0.05) at 12 months. After 12 months of CI experience, cortical responses in noise became more comparable between groups.ConclusionBinaural restoration in SSD patients via cochlear implantation improved speech performance noise and cortical responses. While behavioral performance and cortical auditory responses improved, SSD-CI outcomes remained poorer than that of NH controls in most cases, suggesting only partial restoration of binaural hearing.

Comparison of Speech Recognition and Localization Ability in Single-sided Deaf Patients Implanted With Different Cochlear Implant Electrode Array Designs.

Choice of electrode array (EA) design and differences in outcome are major concerns both to patients with single-sided deafness (SSD) and to surgeons before cochlear implant (CI) surgery. The present work investigates the effects of EA design on 1) insertion depths, and 2) audiological outcomes of SSD CI recipients. Retrospective study. Tertiary academic center. Forty patients with acquired SSD matched according to duration of deafness MAIN OUTCOME MEASURES:: Fourteen CI recipients were implanted with a perimodiolar electrode (cochlear perimodiolar [CPM]), 12 with a shorter lateral wall electrode (cochlear lateral wall [CLW]), and 14 with a longer lateral wall electrode array (medEl lateral wall [MLW]). Postoperative rotational tomography was evaluated to determine cochlear size and EA angle of insertion depth (AID). Binaural speech comprehension in noise (in three configuration presentations) and localization ability were assessed 12 months postoperatively with CI. AID was significantly deeper in MLW (mean 527.94 degrees) compared with the CPM (mean 366.35 degrees) and CLW groups (mean 367.01 degrees). No significant difference in AID was seen between the CPM and CLW groups (difference 0.66 degrees). Cochlear sizes revealed no significant differences between any groups. All three groups showed significant improvement in head shadow effect (difference on average CPM: 6.3 dB SPL, CLW 5 dB SPL, and MLW 4.05 dB SPL) and localization ability at 12 months postoperatively (difference on average CPM: 19.72 degrees, CLW: 24 degrees, and MLW: 12.9 degrees). No significant difference in the extent of audiological benefit was observed between any groups. No effect on binaural benefit was apparent from the selection of the three EA designs in SSD CI recipients. Further studies focusing on subjective results, sound quality, and music perception depending on EA design in SSD CI recipients are needed.

Horizontal sound localisation and speech perception in Bonebridge-implanted single-sided deafness patients.

This study aimed to investigate the benefit of Bonebridge devices in patients with single-sided deafness. Five patients with single-sided deafness who were implanted with Bonebridge devices were recruited in a single-centre study. Participants' speech perception and horizontal sound localisation abilities were assessed at 6 and 12 months post-operatively. Speech intelligibility in noisy environments was measured in three different testing conditions (speech and noise presented from the front, speech and noise presented from the front and contralateral (normal ear) side separately, and speech presented from the ipsilateral (implanted Bonebridge) side and noise from the contralateral side). Sound localisation was evaluated in Bonebridge-aided and Bonebridge-unaided conditions at different stimuli levels (65, 70 and 75 dB SPL). All participants showed a better capacity for speech intelligibility in quiet environments with the Bonebridge device. The speech recognition threshold with the Bonebridge device was significantly decreased at both short- and long-term follow up in the speech presented from the ipsilateral (implanted Bonebridge) side and noise from the contralateral side condition (p < 0.05). Additionally, participants maintained similar levels of sound localisation between the Bonebridge-aided and unaided conditions (p > 0.05). However, the accuracy of localisation showed some improvement at 70 dB SPL and 75 dB SPL post-operatively. The Bonebridge device provides the benefit of improved speech perception performance in patients with single-sided deafness. Sound localisation abilities were neither improved nor worsened with Bonebridge implantation at the follow-up assessments.

Progress in the treatment of single-sided deafness with artificial hearing aids

Single-sided deafness（SSD） is a common disease. Compared with normal hearing people, unilateral deaf patients often suffer from the loss of sound source localization ability and speech recognition in complex environments due to the lack of binaural summation effect, squelch effect, spatial demasking effect, and the presence of head shadow effect. Patients' quality of life and professional activities are always poor. Therefore, this article will review the related definitions of SSD, epidemiology, hazards, and artificial hearing aids in the application of SSD patients.

Single-sided deafness after sudden hearıng loss: late effect on cochlear nerve size.

Single-sided deafness (SSD) is a condition where an individual has non-functional hearing in one ear and receives no clinical benefit from amplification in that ear, with the contralateral ear possessing normal audiometric function. Cochlear implant presents a good choice in rehabilitation of SSD. The presence of a deficient cochlear nerve (CN) has been linked to poor performance with cochlear implants. CN can be measured by imaging techniques. The objective of this study was to compare CN diameter in patients who had a history of single-sided deafness because of sudden hearing loss. Retrospective study where radiologist was blind designed. 53 SSD patients who had a history of sudden hearing loss and MRI at least 5years after the sudden hearing loss were included in this retrospective study. High-resolution 3-D constructive interference in steady state (CISS)-sequence magnetic resonance (MRI) images was review by the neurotology-experienced blind radiologist. Vertical, horizontal and area measurements of cochlear nerve between the deaf and the normal ear were made. There was no statistically significant difference between the normal ear and deaf ear of the subjects in terms of cochlear nerve vertical diameter, horizontal diameter and area. (respectively, p = 0.250; p = 0.183; p = 0.874) CONCLUSION: The numbers of remaining cochlear neurons and spiral ganglion cells in the implanted deaf ears are critical and evidence was not found for spiral ganglion cell loss in the sudden hearing loss deaf ear with SSD in MRI. In the light of all these findings, implantation would be a good choice for rehabilitation in postlingual SSD regardless of auditory deprivation duration.

Cochlear implants in single-sided deafness – clinical results of a Swiss multicentre study

The aim of this multicentre, prospective, open, nonrandomised clinical trial was to demonstrate the clinical efficiency and outcomes of cochlear implants (CIs) in adult patients with post-lingual single-sided deafness (SSD). A group of five left and five right SSD participants were investigated with various clinical tests and questionnaires before and 12 months after CI activation. Changes in hearing thresholds, speech understanding in noise, sound localisation, tinnitus (Tinnitus Handicap Inventory; THI), subjective hearing ability (Speech, Spatial and Qualities of Hearing Scale; SSQ), and quality of life (WHOQOL-BREF) were assessed. In addition, the pre- and postoperative results of the SSD patients were compared with an age- and gender-matched normal hearing control group. Surgery was uncomplicated in all patients. Two years after implantation, 9 of the 10 patients used their CI regularly for an average of more than 11 hours a day. A significant improvement in speech understanding in noise measured in the sound field using the Oldenburg sentence test could be demonstrated in the two situations in which patients with SSD experience the greatest difficulty: speech from the front and noise at the healthy ear, and speech to the implanted ear and noise from the front. The sound localisation test showed significant improvement of the mean localisation error and the root mean square error after CI activation. Furthermore, a significant reduction of the THI was measured, and the SSQ showed a significant improvement in the subscale speech comprehension and in the subscale spatial hearing. Also, quality of life measured with the WHOQOL-BREF showed a general improvement, which was significant in the global subscale. For this questionnaire, there was no significant difference between the normal-hearing control group and the patients after 12 months of CI use. This study confirmed the clinical benefit of cochlear implantation in patients with SSD. The significant improvement of speech understanding in noise, sound localisation, tinnitus perception, subjective hearing ability, and in particular the improved quality of life support the recommendation that patients with recently acquired SSD should be offered a CI. (Clinical trial registration number on clinicaltrial.gov: NCT01749592).

Cross-modal plasticity in adult single-sided deafness revealed by alpha band resting-state functional connectivity

Single-sided deafness (SSD) or profound unilateral hearing loss is the condition where the transfer of acoustic information to the brain is restricted to one ear. SSD impairment is most evident under adverse acoustic environments with overlapping interference, which burdens cognitive resources. It is known that bilateral deafness induces cross-modal brain plasticity within visual cortical areas. Here we investigate whether similar cross-modal plasticity is observed in adult-onset SSD. In SSD patients (n ​= ​29) and matched controls (n ​= ​29) we estimated voxel level resting-state power and functional connectivity in the alpha band (8–12 ​Hz) from magnetoencephalography (MEG) data. We examined both global functional connectivity (mean functional connectivity of each voxel with the rest of the brain), and seeded functional connectivity of primary auditory cortices (A1), primary visual cortices (V1) and posterior cingulate cortex (PCC) of the default mode network (DMN). Power reduction was observed in left auditory cortex. Global functional connectivity showed reduction in frontal cortices and enhancement in visual cortex. Seeded functional connectivity of auditory cortices showed reduction in temporal, frontal and occipital regions, and enhancement in parietal cortex. Interestingly, seeded functional connectivity of visual cortices showed enhancement in visual cortices, inferior parietal lobe, post-central gyrus, and the precuneus, and reduction in auditory cortex. Seeded functional connectivity of PCC showed reduction in frontal cortical regions that are part of the DMN, attention, and working memory networks. Adult-onset SSD exhibited widespread cross-modal brain plasticity involving alterations in auditory, visual, attention, working memory and default mode networks.

Influence of single-sided deafness on the auditory capacity of the better ear.

Patients with single-sided deafness (SSD) are limited by their asymmetric hearing in various areas of everyday life. The aim of this investigation was to perform an age-correlated comparison of the hearing threshold of the better ear of SSD patients with anormal-hearing (NH) reference cohort. In addition, the potential influence of etiology, duration of deafness, and cochlear implantation (CI) of the poorer ear on the peripheral hearing ability of the better ear was investigated. In amulticenter study, the mean bone conduction hearing threshold of the better ear of 413adult SSD patients was compared with that of an NH cohort drawn from ISO 7029:2017 for the frequencies0.5, 1, 2, and 4 kHz. SSD patients showed significantly poorer hearing in the better ear compared to the age-correlated group of NH subjects. CI, duration of deafness, and etiology had no significant effect on the hearing ability of the better ear. The origin of the poorer hearing of the better-hearing ear of SSD patients compared to an age-correlated NH cohort is still unclear. It is most likely acombination of different anatomical, immunological, etiological, and microcirculatory causes, which lead to poorer hearing of the better-hearing ear in SSD patients.

Deaf in one ear: Communication and social challenges of patients with single-sided deafness post-diagnosis

ObjectiveTo understand the communication and social challenges that individuals with SSD face post diagnosis. MethodsFifty-two single-sided deaf patients from all over the world participated in semi-structured interviews. Interviews were digitally recorded, transcribed verbatim, and coded using a thematic analysis approach. ResultsPatients with single sided deafness identified challenges including: increased reliance on family members, decreased sense of autonomy, communication quality changes with family members, information discrepancy across family members and various emotional responses, conflicting information from interactions with multiple medical professionals, and lack of knowledge regarding what to anticipate post diagnosis. ConclusionThis study provides insights into patients’ perspectives around single-sided deafness and its challenges, and the various health care approaches (e.g., patient- and family-centered care, third party disability, patient navigation) that could be implemented post diagnosis to decrease negative experiences and outcomes associated with SSD. Practical ImplicationsThis study has practical implications for improving our understanding of what single-sided deaf patients need and for health professionals to offer better care to current and future populations impacted by single-sided deafness.

Cochlear Place of Stimulation Is One Determinant of Cochlear Implant Sound Quality

Objective: Our aim was to determine the effect of acute changes in cochlear place of stimulation on cochlear implant (CI) sound quality. Design: In Experiment 1, 5 single-sided deaf (SSD) listeners fitted with a long (28-mm) electrode array were tested. Basal shifts in place of stimulation were implemented by turning off the most apical electrodes and reassigning the filters to more basal electrodes. In Experiment 2, 2 SSD patients fitted with a shorter (16.5-mm) electrode array were tested. Both basal and apical shifts in place of stimulation were implemented. The apical shifts were accomplished by current steering and creating a virtual place of stimulation more apical that that of the most apical electrode. Results: Listeners matched basal shifts by shifting, in the normal-hearing ear, the overall spectrum up in frequency and/or increasing voice pitch (F0). Listeners matched apical shifts by shifting down the overall frequency spectrum in the normal-hearing ear. Conclusion: One factor determining CI voice quality is the location of stimulation along the cochlear partition.

Long-term evaluation of sound localisation in single-sided deaf adults fitted with a BAHA device.

To perform a long-term evaluation of the localisation capabilities in the horizontal plane of single-sided deaf patients fitted with a BAHA device. Single-centre retrospective study. Twenty-one adults with single-sided deafness (SSD) with normal hearing in the contralateral ear (pure tone average <20dB, SDS>90%) rehabilitated with a Cochlear BAHA device from 2003 to 2012 on the deaf side over a median follow-up of 8years. The task used in this paper is a sound localisation identification task with a set-up of seven loudspeakers on a semi-circular array at 30-degree intervals performed at three periods: before BAHA, initially and at last follow-up. Our main criterion of judgement was the root-mean-square (RMS) localisation error. In addition, the Bern Benefit in Single-Sided Deafness Questionnaire (BBSS) was administered. The mean RMS localisation error was initially estimated at 64° without any rehabilitation (for a chance level RMS estimated at 81°). Initially, with the BAHA device, the RMS localisation error dropped to 51°. At the last follow-up evaluation, a significant decrease at 23° was noted. Concerning the Bern Questionnaire, 19% of the patients (n=4) did not report any change (score of 0), 33% (n=7) are satisfied (score of +1 or +2) and 48% (n=10) are very satisfied with the BAHA device (score better than +3). Improvement of sound localisation in the horizontal plane for some SSD patients is likely related to altered processing of monaural spectral cues. The time needed to learn to use the azimuth-dependent spectral cues takes time. Long-term follow-up should be considered for studies investigating sound localisation performance.