Unilateral Cochlear Implant Users Research Articles

Integrated bimodal fitting and binaural streaming technology outcomes for unilateral cochlear implant users

Objective Adults typically receive only one cochlear implant (CI) due to cost constraints, with a contralateral hearing aid recommended when there is aidable hearing. Standard hearing aids differ from a CI in terms of processing strategy and function as a separate entity, requiring the user to integrate the disparate signals. Integrated bimodal technology has recently been introduced to address this challenge. The aim of the study was to investigate the performance of unilateral CI users with and without an integrated bimodal fitting and determine whether binaural streaming technology offers additional benefit. Study sample Twenty-six CI users using integrated bimodal technology. Design Repeated measures where outcomes and user experience were assessed using a functional test battery more representative of real life listening (speech perception in noise tests, localisation test, tracking test) and the speech, spatial and qualities-of-hearing scale (SSQ). Results Bimodal outcomes were significantly better than for CI alone. Speech perception in noise improvements ranged from 1.4 dB to 3.5 dB depending on the location of speech and noise. The localisation and tracking tests, and the SSQ also showed significant improvements. Binaural streaming offered additional improvement (1.2 dB to 6.1 dB on the different speech tests). Conclusions Integrated bimodal and binaural streaming technology improved the performance of unilateral CI users.

Objective and Subjective Measures of Spatial Hearing in Unilateral Cochlear Implant Users with Bilateral Profound Hearing Loss

Purpose: The ability to benefit from spatial separation between target and masker signals is important in multi-sound source listening environments. The goal of this study was to measure the spatial release from masking (SRM) in unilateral cochlear implant (CI) users with bilateral profound hearing loss. We also determined the relationships between the SRMs and the self-reported spatial hearing abilities.Methods: Fourteen unilateral CI users with bilateral profound hearing loss participated in this study. The target sentence was always presented to the front of the listener, and the nonfluctuating speech-shaped noise (SSN) or fluctuating speech noise was either co-located with the target (speech at 0°, noise at 0°, S0N0) or spatially separated at ± 90°. The SRM was quantified as the difference between speech recognition thresholds (SRTs) in the co-located and spatially separated conditions. The self-reported spatial hearing abilities were also measured using validated subjective questionnaires.Results: Overall, the SRTs were lower (better) with SSN than with fluctuating speech noise. When the noise was presented to the non-CI ear (speech at 0°, noise at non-CI ear, S0Nnonci), speech-in-noise recognition was the greatest due to head shadow or better-ear listening effect, resulting in the SRMs of approximately 5~6 dB regardless of noise type. When the noise was given to the CI ear (speech at 0°, noise at CI ear, S0Nci), some individuals exhibited positive SRMs (3~8 dB), while others showed negative SRMs, leading to little SRMs overall. When the SSN was given, subjects with less SRMs (less spatial separation benefits on the objective test) reported greater subjective spatial hearing difficulties.Conclusion: The spatial hearing of unilateral CI users varied by the position of the sound source. Listeners' spatial hearing abilities, which are unpredictable from clinical routine tests, need to be assessed by either objective or subjective measures.

Loudness Balancing Optimization for Better Speech Intelligibility, Music Perception, and Spectral Temporal Resolution in Cochlear Implant Users.

The behaviorally based programming with loudness balancing (LB) would result in better speech understanding, spectral-temporal resolution, and music perception scores, and there would be a relationship between these scores. Loudness imbalances at upper stimulation levels may cause sounds to be perceived as irregular, gravelly, or overly echoed and may negatively affect the listening performance of the cochlear implant (CI) user. LB should be performed after fitting to overcome these problems. The study included 26 unilateral Med-EL CI users. Two different CI programs based on the objective electrically evoked stapedial reflex threshold (P1) and the behaviorally program with LB (P2) were recorded for each participant. The Turkish Matrix Sentence Test (TMS) was applied to evaluate speech perception; the Random Gap Detection Test (RGDT) and Spectral-Temporally Modulated Ripple Test (SMRT) were applied to evaluate spectral temporal resolution skills; the Mini Profile of Music Perception Skills (mini-PROMS) and Melodic Contour Identification (MCI) tests were applied to evaluate music perception, and the results were compared. Significantly better scores were obtained with P2 in TMS tests performed in noise and quiet. SMRT scores were significantly correlated with TMS in quiet and noise, and mini-PROMS sound perception results. Although better scores were obtained with P2 in the mini-PROMS total score and MCI, a significant difference was found only for MCI. The data from the current study showed that equalization of loudness across CI electrodes leads to better perceptual acuity. It also revealed the relationship between speech perception, spectral-temporal resolution, and music perception.

Listening-Related Fatigue in New and Experienced Adult Cochlear Implant Users.

Active listening in everyday settings is challenging and requires substantial mental effort, particularly in noisy settings. In some cases, effortful listening can lead to significant listening-related fatigue and negatively affect quality of life. However, our understanding of factors that affect the severity of fatigue is limited. Hearing aids and cochlear implants (CIs) can improve speech understanding and thus, potentially, reduce listening effort and fatigue. Some research supports this idea for adult hearing aid users with mild-to-moderate hearing loss, but similar work in CI users is very limited. This study examined (1) longitudinal changes in listening-related fatigue in new and established CI users, and (2) relationships between demographic and audiologic factors and preimplantation and postimplantation listening-related fatigue. Participants included an experimental group of 48 adult CI candidates receiving either a unilateral implant (n = 46) or simultaneous, bilateral implants (n = 2) and a control group of 96 experienced (>12 months experience) adult CI users (50 unilateral, 46 bilateral). Listening-related fatigue was evaluated using the 40-item version of the Vanderbilt Fatigue Scale for Adults. Experimental group ratings were obtained before implantation and again at 0.5-, 1-, 2-, 3-, 6-, and 12-month(s) postactivation. Control group participants completed the scale twice-upon study entry and approximately 3 months later. Additional measures, including a social isolation and disconnectedness questionnaire, hearing handicap inventory, and the Effort Assessment Scale, were also administered at multiple time points. The role of these measures and select demographic and audiologic factors on preimplant and postimplant fatigue ratings were examined. Adult CI candidates reported significantly more fatigue, greater self-perceived hearing handicap, greater listening effort, and more social isolation than experienced adult CI users. However, significant reductions in fatigue and effort were observed within 2 weeks postimplantation. By 3 months, there were no significant differences in fatigue, effort, hearing handicap, or social isolation between new CI recipients and experienced CI users. Secondary analyses revealed that age at onset of hearing loss (before or after 2 years of age) and subjective hearing handicap contributed significantly to the variance of preimplantation fatigue ratings (those with higher handicap reported higher fatigue). In contrast, variance in postimplantation fatigue ratings was not affected by age of hearing loss onset but was affected by gender (females reported more fatigue than males) and subjective ratings of effort, handicap, and isolation (those reporting more effort, handicap, and isolation reported more fatigue). Listening-related fatigue is a significant problem for many CI candidates, as well as for many experienced unilateral and bilateral CI users. Receipt of a CI significantly reduced listening-related fatigue (as well as listening effort, hearing handicap, and social isolation) as soon as 2 weeks post-CI activation. However, the magnitude of fatigue-related issues for both CI candidates and experienced CI users varies widely. Audiologic factors, such as hearing loss severity and aided speech recognition, were not predictive of individual differences in listening-related fatigue. In contrast, strong associations were observed between perceived hearing handicap and listening-related fatigue in all groups suggesting fatigue-related issues may be a component of perceived hearing handicap.

Language, cognitive, and speech in noise perception abilities of children with cochlear ımplants: a comparative analysis by implantation period and bilateral versus unilateral cochlear implants.

The purpose of this study was to compare the language, cognitive, and speech in noise (SiN) perception abilities of children with cochlear implants (CIs) to those of their peers with NH by grouping them according to their implantation period (12-18months/19-24months) and unilateral/bilateral CI use. The sample comprised 50 children with cochlear implants (CIs) and 20 children with normal hearing (NH), ages 6-9years. Children's language, cognitive, and speech in noise (SiN) perception skills were assessed. Children with CIs between 12 and 18months and 19 and 24months performed more poorly than children with NH on language, verbal memory (VM), verbal-short-term memory (V-STM), verbal working memory (V-WM), rapid naming, and speech in noise (SiN) perception abilities measures (p < 0.001). In addition, children with CIs between 19 and 24months performed worse on rapid naming and V-WM tasks than children with CIs between 12 and 18months (p < 0.017). Children with unilateral and bilateral CI performed more poorly than children with NH on language, VM, V-STM, V-WM, rapid naming, and SiN perception abilities assessments (p < 0.001). Additionally children with unilateral CI users performed poorly than children with bilateral CI users on SiN perception (p < 0.017). In children with congenital hearing loss (CHL), cochlear implantation between 12 and 18months or sequential bilateral implantation is not sufficient for these children to perform like their NH peers in language, cognitive, and SiN perception abilities. In addition, intervention approaches should focus not only on increasing language skills, but also on cognitive abilities.

Speech-in-Noise Recognition in School-Aged Children with Hearing Loss: Evidence of a Critical Condition

Previous research findings demonstrated that cochlear implants (CIs) users have essential challenges with speech recognition in the presence of background noise. Therefore, this study aimed to determine speech-in-noise (SiN) perception in Persian school-aged children with CIs/hearing aids (HAs) compared to their peers with normal hearing (NH). The research was administered as a cross-sectional study. Speech-in-noise performance in thirty-three school-aged children with hearing loss (19 unilateral CIs users and 14 bilateral HAs users) was compared to twenty school-aged children with normal hearing by using the Persian Lexical Neighborhood Tests (PLNTs). To make sure that floor or ceiling effects would not affect the children’s performance, the PLNTs were performed by the sound field at different levels of signal-to-noise ratio (SNR). The SiN performance on all four subscales of the PLNTs was significantly poorer in Persian school-aged CIs/HAs users than their peers with NH for all stepwise increases in the SNR (P &lt; 0.001). The Persian school-aged CIs users experience a critical condition related to listening spectrally degraded speech in noisy environments such as home, school, and classroom due to SiN perception insufficiency.

Evaluating Listening Effort in Unilateral, Bimodal, and Bilateral Cochlear Implant Users.

Evaluate listening effort (LE) in unilateral, bilateral, and bimodal cochlear implant (CI) users. Establish an easy-to-implement task of LE that could be useful for clinical decision making. Prospective cohort study. Tertiary neurotology center. The Sentence Final Word Identification and Recall Task, an established measure of LE, was modified to include challenging listening conditions (multitalker babble, gender, and emotional variation; test), in addition to single-talker sentences (control). Participants listened to lists of sentences in each condition and recalled the last word of each sentence. LE was quantified by percentage of words correctly recalled and was compared across conditions, across CI groups, and within subjects (best aided vsmonaural). A total of 24 adults between the ages of 37 and 82 years enrolled, including 4 unilateral CI users (CI), 10 bilateral CI users (CICI), and 10 bimodal CI users (CIHA). Task condition impacted LE (P < .001), but hearing configuration and listener group did not (P = .90). Working memory capacity and contralateral hearing contributed to individual performance. This study adds to the growing body of literature on LE in challenging listening conditions for CI users and demonstrates feasibility of a simple behavioral task that could be implemented clinically to assess LE. This study also highlights the potential benefits of bimodal hearing and individual hearing and cognitive factors in understanding individual differences in performance, which will be evaluated through further research.

QoL, CIs, QALYs, and Individualized Rehabilitation: The Clinical and Practical Benefits of Regularly Assessing the Quality of Life of Adult Cochlear Implant Recipients.

This study aimed to report quality of life (QoL) scores in unilateral cochlear implant (CI) users and to generate guidance for clinicians on using QoL measures to individualize CI counselling and rehabilitation and to increase access to CIs as a mode of rehabilitation. Participants (n = 101) were unilateral CI users with single-sided deafness (SSD; n = 17), asymmetrical hearing loss (AHL; n = 26), or bilateral hearing loss (Uni; n = 58). Generic QoL was assessed via the Health Utilities Index (HUI-3), and disease-specific QoL was assessed via the Speech, Spatial, and Qualities of Hearing scale (SSQ12) and Nijmegen CI Questionnaire (NCIQ) at preimplantation and at 6 and 12 months of CI use. All groups had significantly increased HUI-3 scores at both intervals. The SSD group showed significant benefit on the SSQ12 at visit 3, the AHL group showed significant benefit on the SSQ12 and most NCIQ subdomains at both intervals, and the Uni group showed significant benefit with both tests at both intervals. Unilateral CI recipients demonstrate improved QoL within the first 12 months of device use. Regular assessment with generic and disease-specific questionnaires has the potential to play an important role in personalizing treatment and possibly in increasing access to CI provision.

Preliminary evaluation of computer-assisted home training for French cochlear implant recipients.

For French cochlear implant (CI) recipients, in-person clinical auditory rehabilitation is typically provided during the first few years post-implantation. However, this is often inconvenient, it requires substantial time resources and can be problematic when appointments are unavailable. In response, we developed a computer-based home training software ("French AngelSound™") for French CI recipients. We recently conducted a pilot study to evaluate the newly developed French AngelSound™ in 15 CI recipients (5 unilateral, 5 bilateral, 5 bimodal). Outcome measures included phoneme recognition in quiet and sentence recognition in noise. Unilateral CI users were tested with the CI alone. Bilateral CI users were tested with each CI ear alone to determine the poorer ear to be trained, as well as with both ears (binaural performance). Bimodal CI users were tested with the CI ear alone, and with the contralateral hearing aid (binaural performance). Participants trained at home over a one-month period (10 hours total). Phonemic contrast training was used; the level of difficulty ranged from phoneme discrimination in quiet to phoneme identification in multi-talker babble. Unilateral and bimodal CI users trained with the CI alone; bilateral CI users trained with the poorer ear alone. Outcomes were measured before training (pre-training), immediately after training was completed (post-training), and one month after training was stopped (follow-up). For all participants, post-training CI-only vowel and consonant recognition scores significantly improved after phoneme training with the CI ear alone. For bilateral and bimodal CI users, binaural vowel and consonant recognition scores also significantly improved after training with a single CI ear. Follow-up measures showed that training benefits were largely retained. These preliminary data suggest that the phonemic contrast training in French AngelSound™ may significantly benefit French CI recipients and may complement clinical auditory rehabilitation, especially when in-person visits are not possible.

Direct Elicitation of Cortical Auditory Evoked Potentials by Electrical Stimulation and Their Use to Verify the Most Comfortable Level of Stimulation in Cochlear Implant Users

Introduction: This study was designed to investigate the use of electrically evoked cortical auditory evoked potentials (eCAEPs) as a tool for cochlear implant (CI) verification, the relationships between the site and intensity of stimulation and the detection rates and morphologies of eCAEPs as well as investigate whether correlations exist between the morphologies of eCAEPs and speech perception in quiet and in noise, duration of hearing loss, age at implantation, whether the hearing loss bilateral or single-sided and the electrode current level required to elicit MCL stimulation. Methods: 32 adult unilateral CI users with postlingual hearing loss were enrolled. The stimuli were 1 kHz biphasic alternating pulses and were presented at either the behaviorally measured MCL or 50% of this value (MCL_0.5) via the CI fitting software. Pulses were directed to apical, medial, or basal electrodes. CAEPs were recorded from a scalp electrode placed at the vertex, low forehead, and contralateral mastoid and were evaluated by two electrophysiologists. Results: Overall, eCAEPs could be detected in 31/32 users when stimulating at MCL, and in 29/32 users when stimulating at MCL_0.5. The detection rates were 31, 31, and 28/32 for apical, medial, and basal stimulation at MCL, and 29, 29, and 26/32 at MCL_0.5. Significant differences in eCAEP amplitudes and latencies were observed across electrodes and stimulation levels. No significant correlations were found between eCAEP latencies and amplitudes and user age, duration of deafness prior to CI surgery, or with bilateral versus single-sided hearing loss, nor with the charge level required to elicit MCL, or with speech perception scores in quiet. Peak latencies correlated with speech perception scores in some configurations of speech-in-noise. Conclusion: eCAEPs can readily be elicited in the majority of adult CI users and show normal waveform characteristics at stimulation levels corresponding to MCL, as well as at basal, medial, and apical electrode stimulation sites. Neither the latencies nor amplitudes of eCAEPs are confounded by variables of age, duration of deafness prior to CI surgery, or the laterality of hearing loss. eCAEPs are a useful, objective method evaluate sound perception in CI users.

Training spatial hearing in unilateral cochlear implant users through reaching to sounds in virtual reality

Background and PurposeUse of unilateral cochlear implant (UCI) is associated with limited spatial hearing skills. Evidence that training these abilities in UCI user is possible remains limited. In this study, we assessed whether a Spatial training based on hand-reaching to sounds performed in virtual reality improves spatial hearing abilities in UCI usersMethodsUsing a crossover randomized clinical trial, we compared the effects of a Spatial training protocol with those of a Non-Spatial control training. We tested 17 UCI users in a head-pointing to sound task and in an audio-visual attention orienting task, before and after each training. <br>Study is recorded in clinicaltrials.gov (NCT04183348).ResultsDuring the Spatial VR training, sound localization errors in azimuth decreased. Moreover, when comparing head-pointing to sounds before vs. after training, localization errors decreased after the Spatial more than the control training. No training effects emerged in the audio-visual attention orienting task.ConclusionsOur results showed that sound localization in UCI users improves during a Spatial training, with benefits that extend also to a non-trained sound localization task (generalization). These findings have potentials for novel rehabilitation procedures in clinical contexts.

Residual Hearing Does Not Influence the Effectiveness of Beamforming when Using a Cochlear Implant in Conjunction with Contralateral Routing of Signals

Introduction: Contralateral routing of signals (CROS) overcomes the head shadow effect by redirecting speech signals from the contralateral ear to the better-hearing cochlear implant (CI) ear. Here we tested the performance of an adaptive monaural beamformer (MB) and a fixed binaural beamformer (BB) using the CROS system of Advanced Bionics. Methods: In a group of 17 unilateral CI users, we evaluated the benefits of MB and BB for speech recognition by measuring speech reception threshold (SRT) with and without beamforming. MB and BB were additionally evaluated with signal-to-noise ratio (SNR) measurements using a KEMAR manikin. We also assessed the effect of residual hearing in the CROS ear on the benefits of MB and BB. Speech was delivered in front of the listener in a background of homogeneous 8-talker babble noise. Results: With CI-CROS in omnidirectional settings with the T-mic active on the CI as a reference, BB significantly improved SRT by 1.4 dB, whereas MB yielded no significant improvements. The difference in effects on SRT between the two beamformers was, however, not significant. SNR effects were substantially larger, at 2.1 dB for MB and 5.8 dB for BB. CI-CROS with default omnidirectional settings also improved SRT and SNR by 1 dB over CI alone. Residual hearing did not significantly affect beamformer performance. Discussion: We recommend the use of BB over MB for CI-CROS users. Residual hearing in the CROS ear is not a limiting factor for fitting a CROS device, although a bimodal option should be considered.

Capturing Visual Attention With Perturbed Auditory Spatial Cues.

Lateralized sounds can orient visual attention, with benefits for audio-visual processing. Here, we asked to what extent perturbed auditory spatial cues-resulting from cochlear implants (CI) or unilateral hearing loss (uHL)-allow this automatic mechanism of information selection from the audio-visual environment. We used a classic paradigm from experimental psychology (capture of visual attention with sounds) to probe the integrity of audio-visual attentional orienting in 60 adults with hearing loss: bilateral CI users (N = 20), unilateral CI users (N = 20), and individuals with uHL (N = 20). For comparison, we also included a group of normal-hearing (NH, N = 20) participants, tested in binaural and monaural listening conditions (i.e., with one ear plugged). All participants also completed a sound localization task to assess spatial hearing skills. Comparable audio-visual orienting was observed in bilateral CI, uHL, and binaural NH participants. By contrast, audio-visual orienting was, on average, absent in unilateral CI users and reduced in NH listening with one ear plugged. Spatial hearing skills were better in bilateral CI, uHL, and binaural NH participants than in unilateral CI users and monaurally plugged NH listeners. In unilateral CI users, spatial hearing skills correlated with audio-visual-orienting abilities. These novel results show that audio-visual-attention orienting can be preserved in bilateral CI users and in uHL patients to a greater extent than unilateral CI users. This highlights the importance of assessing the impact of hearing loss beyond auditory difficulties alone: to capture to what extent it may enable or impede typical interactions with the multisensory environment.

Features of beta-gamma phase-amplitude coupling in cochlear implant users derived from EEG

Cochlear implants (CIs) allow patients with severe to profound hearing loss to gain or regain their sense of hearing. However, the objective assessment of auditory rehabilitation in CI users remains a challenge. In particular, the utility of phase-amplitude coupling (PAC) for evaluating postoperative rehabilitation of CI users remains unknown. In the present study, we conducted an oddball paradigm with stimuli varying in sample speech syllables and collected electroencephalography (EEG) signals for 10 CI users at the time the implant was activated and 180 days after activation. Twelve normal-hearing subjects served as controls. We explored the oscillatory properties of the neural response to syllable incongruence and the cross-frequency coupling between multiple frequencies in CI users. We found that beta-gamma coupling appeared to be enhanced in CI users compared with normal controls and this difference gradually disappeared with increasing implantation time. The present results suggest that predictively encoded auditory pathways are gradually restored in CI users. In addition, the PAC feature in unilateral CI users was found to be lateralized in the auditory cortex, which was consistent with previous studies of auditory-evoked cortical activity. Therefore, PAC may be a reference biomarker for the rehabilitation of speech discrimination in CI users.

One Click Is Not Enough: Anatomy-Based Fitting in Experienced Cochlear Implant Users.

To evaluate a new methodological approach of applying anatomy-based fitting (ABF) in experienced cochlear implant (CI) users. Three experienced unilateral and bilateral CI users with postlingual hearing loss. Postoperative imaging, via a high-volume Dyna computed tomography, and exact electrode measurement positions were integrated into the clinical fitting software following a new procedure, which adapted individual frequency bandwidths within the audio processor. Speech perception in quiet and noise, clinical mapping, and self-perceived level of auditory benefit were assessed. For each CI user, ABF mapping provided better speech perception in quiet and in noise compared with the original clinical fitting mapping. In addition, ABF mapping was accepted in CI users despite unequal bilateral array insertion depths and lengths; however, acceptance was only established if the point of first electrode contact was less than 230 Hz. ABF mapping increased the acceptance in CI users with longer electrode arrays and in bilateral CI users who were unsatisfied with their device experience. A larger prospective, randomized investigation is currently underway to assess longitudinal outcomes with ABF mapping.

Evaluation of the Effect of Musical Perception Activities on Speech Perception in Adult Cochlear Implant Users.

This study aimed to evaluate clinical musical perception, analyze the relationship between speech recognition and music perception, and investigate the effects of a three-month musical perception activities on these parameters in adult cochlear implant (CI) users with post-lingual hearing loss. Free-field hearing and speech tests in a quiet environment, the Turkish matrix test, and the Turkish version of the clinical assessment of musical perception test were performed on 18 adult unilateral CI users before and after the three-month music training. Results were compared with those of 18 healthy controls. Prior to the musical perception activities, word recognition scores, Turkish matrix test results, and 500, 1000, and 6000 Hz free-field hearing thresholds were significantly correlated with the clinical assessment of musical perception test scores in the CI group (p<0.047). Timbre recognition scores (p=0.019) had improved significantly in the CI group after the three-month musical perception activities. On the other hand, timbre recognition scores had significantly affected the Turkish matrix test results (R2adjusted=0.56). Our study showed that speech perception in noise and clinical musical perception measurements affected each other in CI users. The inclusion of musical perception activities to support an auditory rehabilitation program may contribute to increased speech recognition skills in noise.

The evaluation of cochlear implant users’ acoustic change detection ability

Objectives This study aimed to evaluate the relationship between behaviourally acquired Acoustic Change Detection Test (ACDT) responses and electrophysiologically obtained Acoustic Change Complex (ACC) responses in participants with Cochlear Implant (CI). Methods 28 unilateral adult CI users (mean age 41) participated in the study. In behavioural test session, ACDT and speech tests were administered. In electrophysiological test session, sound onset and ACC responses of participants stimulated by/ui/speech structure were recorded and N1–P2 peak-to-peak amplitude and N1 latencies were determined. Results No significant correlation was found between individuals’ behavioural and electrophysiological responses but it was observed that individuals dived into two clusters in terms of ACDT responses (p < 0.05). A statistically significant difference was found between the mean ACC amplitudes of the clusters. No statistically significant difference was observed between the mean ACC N1 latency findings of the clusters, suggesting that ACC amplitude may be a better predictor than latency in auditory discrimination. Conclusion ACC measurement may be a potential clinical tool to evaluate auditory discrimination performance in individuals with CI, but using the electrophysiological and behavioural tests together may provide a more holistic perspective.

Cortical auditory evoked potential in cochlear implant users: An objective method to improve speech perception.

ObjectiveTo investigate if cortical auditory evoked potential (CAEP) measures can be used to verify the cochlear implant (CI) map and consequently improve CI outcomes in adults with bilateral hearing loss.DesignCAEPs were measured in CI recipients using the speech tokens /m/, /g/, /t/ and /s/. If CAEP responses were present for all speech tokens, the participant’s map was considered “satisfactory”. If CAEP responses were absent, the CI map was considered “unsatisfactory” and therefore adjusted and CAEP measures repeated. This was repeated until auditory potentials were seen in response to all four speech tokens. Speech testing was conducted pre-CI, as well as before and after CAEP-guided map adjustments.Results108 adult unilateral CI users participated, whose sound processors were previously programmed using subjective methods. 42 CI users elicited a CAEP response to all four speech tokens and therefore no further mapping adjustments were made. 66 subjected lacked a CAEP response to at least one speech token and had their CI map adjusted accordingly. Of those, 31 showed a CAEP response to all four speech tokens, and the average speech score significantly improved after CI map adjustments based on CAEP responses.ConclusionCAEP’s are an objective tool that can be used to guide and verify CI mapping in adults CI users. Significant improvement in speech scores was observed in participants who had their CI map adjusted based on CAEP responses.

Sound Localization in Unilateral Cochlear Implant Users

Purpose: Sound is localized by two ears. People with bilaterally severe-to-profound hearing loss may struggle to identify the direction of a sound if their hearing device delivers sound only one ear due to the loss of binaural advantage. The purpose of this study was to systematically investigate the sound localization performance of people with unilateral cochlear implant users. Methods: Ten unilateral cochlear implant users and 10 normal hearing adults participated in this study. Sound localization tests were conducted using five stimuli (speech, speech with noise, 500 Hz warble tone, 1 kHz warble tone, and 4 kHz warble tone) presented from eight loud-speakers. Correct responses and root- mean-square errors were obtained to investigate the localization performances and error patterns. Additional factors including the Korean-Speech Spatial and Qualities of Hearing Questionnaire were also analyzed. Results: Localization performance was significantly poor in the unilateral cochlear implant group showing polar patterns toward their hearing side. While the normal hearing group showed better localization for speech in quiet conditions compared to 500 Hz warble tone, the cochlear implant group did not show any statistical difference in performance across the stimuli due to their very poor performance. The Korean-Speech Spatial and Qualities of Hearing Questionnaire was associated with localization performance in limited conditions. Conclusion: The present study revealed that unilateral cochlear implant users correctly localize a sound at nearly chance levels. The Korean-Speech Spatial and Qualities of Hearing Questionnaire predict localization performance for unilateral cochlear implant users only for particular conditions.

‘Musical effort’ and ‘musical pleasantness’: a pilot study on the neurophysiological correlates of classical music listening in adults normal hearing and unilateral cochlear implant users

Objective This pilot case-control study is aimed to estimate ‘musical effort’ and ‘musical pleasantness’ in adults normal hearing (NH) and Unilateral Cochlear Implant (UCI) users via neurophysiological indices and a cognitive-behavioural approach. Methods 7 NH and 7 UCI subjects underwent electroencephalographic (EEG) recording with two EEG indices, Approach Withdrawal (AW) and Workload (WI), and behavioural tests conducted during a forced-choice musical emotion recognition task performed in quiet and noise in two emotional conditions. Results Musical effort in terms of WI did not vary between conditions and groups. Inversely, for AW, statistically significant differences in noisy conditions were observed between groups, indicating a difficulty for the patients in discriminating the musical pleasantness in noise. However, self-reported data suggest the ability of UCI to cognitively evaluate the stimulus in terms of both auditory difficulty and pleasantness. Conclusion Findings suggest the possible relevance of the Cochlear Implant in supporting the patients’ effort in listening to music in noise, allowing a pleasant enjoyment in the quiet condition. Overall, this study appears worthy of interest and paves the way for further investigation by providing data on the neurophysiological perception of music.