Implant Users Research Articles

The Acoustic Change Complex Compared to Hearing Performance in Unilaterally and Bilaterally Deaf Cochlear Implant Users.

Objectives:Clinical measures evaluating hearing performance in cochlear implant (CI) users depend on attention and linguistic skills, which limits the evaluation of auditory perception in some patients. The acoustic change complex (ACC), a cortical auditory evoked potential to a sound change, might yield useful objective measures to assess hearing performance and could provide insight in cortical auditory processing. The aim of this study is to examine the ACC in response to frequency changes as an objective measure for hearing performance in CI users.Design:Thirteen bilaterally deaf and six single-sided deaf subjects were included, all having used a unilateral CI for at least 1 year. Speech perception was tested with a consonant-vowel-consonant test (+10 dB signal-to-noise ratio) and a digits-in-noise test. Frequency discrimination thresholds were measured at two reference frequencies, using a 3-interval, 2-alternative forced-choice, adaptive staircase procedure. The two reference frequencies were selected using each participant’s frequency allocation table and were centered in the frequency band of an electrode that included 500 or 2000 Hz, corresponding to the apical electrode or the middle electrode, respectively. The ACC was evoked with pure tones of the same two reference frequencies with varying frequency increases: within the frequency band of the middle or the apical electrode (+0.25 electrode step), and steps to the center frequency of the first (+1), second (+2), and third (+3) adjacent electrodes.Results:Reproducible ACCs were recorded in 17 out of 19 subjects. Most successful recordings were obtained with the largest frequency change (+3 electrode step). Larger frequency changes resulted in shorter N1 latencies and larger N1-P2 amplitudes. In both unilaterally and bilaterally deaf subjects, the N1 latency and N1-P2 amplitude of the CI ears correlated to speech perception as well as frequency discrimination, that is, short latencies and large amplitudes were indicative of better speech perception and better frequency discrimination. No significant differences in ACC latencies or amplitudes were found between the CI ears of the unilaterally and bilaterally deaf subjects, but the CI ears of the unilaterally deaf subjects showed substantially longer latencies and smaller amplitudes than their contralateral normal-hearing ears.Conclusions:The ACC latency and amplitude evoked by tone frequency changes correlate well to frequency discrimination and speech perception capabilities of CI users. For patients unable to reliably perform behavioral tasks, the ACC could be of added value in assessing hearing performance.

Postlingually Deafened Adult Cochlear Implant Users With Prolonged Recovery From Neural Adaptation at the Level of the Auditory Nerve Tend to Have Poorer Speech Perception Performance.

This study investigated the effects of two temporal response properties of the auditory nerve (i.e., neural adaptation and recovery from neural adaptation) on speech perception performance in postlingually deafened adult cochlear implant (CI) users. Study participants included 18 postlingually deafened adults who were Cochlear Nucleus device users with a full electrode array insertion in the test ear(s). Neural adaptation and adaptation recovery of the auditory nerve (AN) were evaluated using electrophysiological measures of the electrically evoked compound action potential (eCAP). The amount of neural adaptation was quantified by the adaptation index within three time windows: 0 to 8.89 (window 1), 44.44 to 50.00 (window 2), and 94.44 to 100.00 ms (window 3). The speed of neural adaptation was estimated using a two-parameter power law function. To evaluate adaptation recovery of the AN, eCAPs to the last pulse of the 100-ms pulse train were recorded at masker-probe-intervals ranging from 1.054 to 256 ms in logarithmic steps. The amount of adaptation recovery was quantified by the adaptation recovery ratio. The time-constant of adaptation recovery was estimated using an exponential function with up to three components. Speech perception performance was evaluated by measuring consonant-nucleus-consonant (CNC) word scores presented in quiet and in speech-shaped noise at a signal-to-noise ratio (SNR) of +10 dB. One-tailed Pearson Product Moment correlation tests were used (1) to assess the associations among parameters of neural adaptation and adaptation recovery and (2) to evaluate the strength of association between these parameters and CNC word scores measured in quiet and in noise. The contributions of different parameters quantifying neural adaptation and adaptation recovery on speech perception scores were evaluated using multivariable linear regression analyses. The Pearson Product Moment correlation coefficient demonstrated a moderate, negative correlation between the speed of adaptation recovery and CNC word scores measured in quiet and in noise. The speed of adaptation recovery accounted for 14.1% of variability in CNC word scores measured in quiet and 16.7% of variability in CNC word scores measured in noise. The correlation strengths between CNC word scores and the adaptation index, the adaptation recovery ratio and the speed of neural adaptation ranged from negligible to weak. The speed of adaptation recovery plays a more important role than other features of neural adaptation and adaptation recovery of the AN in speech perception in postlingually deafened adult CI users. Patients with prolonged adaptation recovery tend to show poorer speech perception performance.

Non-barrier contraceptive use patterns among Latina adolescents attending California reproductive health centers: A longitudinal study

ObjectivesTo describe use of non-barrier contraceptives over a 9-month period, consistency in method use, and identify factors associated with method nonuse, switching, and consistency among Latina adolescents attending California sexual and reproductive health (SRH) centers. Study designWe conducted a cohort study using data self-reported at baseline, and 3- and 9-months post-baseline. The analysis included 1162 sexually active adolescents aged 18 to 19 who self-identified as female and Latina, indicated that they were not currently pregnant or trying to become pregnant, and who attended California SRH centers between June 2016 and June 2020. We used binomial generalized multivariable linear models with a log link to assess the likelihood of nonbarrier method consistency, switching, and non-use. ResultsAt baseline, 453 of 1162 (39%) of respondents were using short-acting methods (pill, patch, ring, or injection), 113 of 1162 (9.7%) were using long-acting methods (implants or intrauterine devices [IUDs]), and 596 of 1162 (51.3%) reported using neither short- nor long-acting methods. Over a 9-month period, 22/33 (66.7%) of those using IUDs consistently used the method, which was a statistically greater frequency of consistency than individuals who selected other nonbarrier methods (270/530 [50.9%], aRR: 1.40; 95% CI: 1.11, 1.77). Implant users had rates of method consistency similar to users of other nonbarrier methods (aRR: 1.11; 95% CI: 0.89, 1.38). Factors independently associated with method consistency included being older, having never been pregnant, having greater perceived risk of pregnancy, and greater contraceptive knowledge. ConclusionSexually active Latina adolescents attending California SRH centers who were not trying to become pregnant maintained consistent contraceptive use more frequently when using an IUD. Using a patient-centered approach, contraceptive counseling for Latina adolescents can describe the combined efficacy and contraceptive stability offered by IUDs should patients desire it. ImplicationsThis study addressees gaps in knowledge about U.S. Latina adolescents’ contraceptive use patterns. We demonstrate that IUD users, and not implant users, appear more likely to consistently use their method than those using non-LARC methods. Patient-centered contraceptive counseling for Latina adolescents can describe the greater contraceptive stability that IUDs may offer.

Engaging effort improves efficiency during word recognition in cochlear implant users

Cochlear Implant (CI) users must cope with the degraded spectral input received through their device. This reduced quality leads to changes in how words are recognized: lexical access is delayed, leading to differences in competition between lexical candidates. CI users also report increased effort and fatigue during language processing, but effort is not clearly related to improved accuracy. We investigated the role that listening effort plays in the dynamics of word recognition. We related lexical competition and listening effort in 77 post-lingually deaf CI users with Visual World Paradigm and pupillometry tasks. Subjects also completed measures of peripheral auditory function (spectral ripple discrimination and temporal modulation detection). We used the difference in pupil size during the recognition of spoken and written words to isolate effort for spoken word recognition. Difference in pupil size predicted efficiency in the spoken word recognition task, over and above age and peripheral fidelity. That is, CI users who engage more effort were faster to recognize words and showed lexical competition similar to normal hearing listeners. This interacted with spectral resolution: better discrimination offsets the need to engage effort. This suggests that listening effort can be engaged to improve efficiency during word recognition.

Cochlear implant users show unexpected flexibility when recognizing words in challenging conditions

For typical listeners in quiet, lexical access occurs immediately. Multiple candidates are activated at word onset and subsequently updated as the word unfolds. For cochlear Implant (CI) users, this process changes to cope with their degraded input: CI users delay lexical access until a substantial portion of a word is heard, a profile termed ‘wait-and-see’. However, it is unclear whether this profile is adaptive or simply a result of deficient input. We addressed this using a paradigm in which neutral carrier sentences (“now click on the…”) were interrupted by periodic bursts of noise, even as target words were always clean. This expected difficulty condition was compared to trials in which both sentences and targets were in quiet or in noise. We used the Visual World Paradigm to assess the timecourse of lexical access and competition. Relative to normal hearing controls, CI users (N = 22) showed a robust wait-and-see profile in noise, delaying target fixations and reducing competition. In trials where noise was expected but the target was clean, CI users initially showed a wait-and-see response but rapidly recovered to reach quiet-like performance. This indicates that wait-and-see may be adaptive for challenging conditions, providing flexibility as listeners process words in real time.

Subjective Preference of Bilateral Cochlear Implant User Using Devices Manufactured by Two Different Cochlear Implant Companies

Subjective Preference of Bilateral Cochlear Implant User Using Devices Manufactured by Two Different Cochlear Implant Companies

The Impact of the COVID-19 Lockdown on Quality of Life in Adult Cochlear Implant Users: A Survey Study.

Background: The COVID-19 pandemic rapidly spread through Europe in the first months of 2020. On the 9th of March 2020, the Italian government ordered a national lock-down. The study’s objectives were: to investigate the effect of lockdown on CI users; and to detect the difference in the perception of discomfort existing between unilateral cochlear implant (UCI) users and bilateral cochlear implant (BCI) users, due to the lockdown experience. Methods: A 17-item, web-based, anonymous online survey was administered to 57 CI users, exploring hearing performance, emotions, practical issues, behavior, and tinnitus. Participation in the study was voluntary. Results: all CI users obtained an abnormal score in all questionnaire themes. For the emotion theme and the practical issue theme, the age range 61–90 showed a significant difference between UCI and BCI users in favor of BCI users (emotion theme: UCI mean = 3.9, BCI mean = 2.3, p = 0.0138; practical issues: UCI mean = 4, BCI mean = 3, p = 0.0031). Conclusions: CI users experienced the lockdown negatively as regards behavior, emotions, hearing performance, and in practical issues. CI subjects with UCI in old age suffered more from the experience of lockdown than subjects with BCI in the same age, with regards to emotions and practical issues.

Association of Self-Reported Coping Strategies With Speech Recognition Outcomes in Adult Cochlear Implant Users.

To characterize the degree to which individual coping strategies may influence speech perception after cochlear implantation. Retrospective cohort study. Tertiary referral center. Adult, postlingually deaf cochlear implant recipients. The Coping Orientation to Problems Experience inventory, a validated, multidimensional self-reported coping scale, was administered preoperatively. Speech perception was measured using consonant-nucleus-consonant (CNC) phoneme and word scores, AzBio sentence accuracy in quiet and noise, and Hearing in Noise Test sentences in quiet preoperatively and at 1, 3, and 6 months postoperatively. Quality of life was measured with the Hearing Implant Sound Quality Index and the Nijmegen Cochlear Implant Questionnaire. Thirty-six patients were included in this study. Mean age at surgery was 70.7 ± 11.4 years. Acceptance was associated with a decreased AzBio in noise score in the 6 months after CI (regression coefficient b = -0.05; 95% confidence interval [CI], -0.07 to -0.03; p < 0.01). Denial was associated with a decreased AzBio in quiet score (b = -0.05; 95% CI, -0.09 to -0.01; p < 0.05), whereas humor was associated with an increased AzBio in quiet score (b = 0.02; 95% CI, 0.01 to 0.04; p < 0.05). Humor was also associated with an increased Hearing in Noise Test score (b = 0.05; 95% CI, 0.02 to 0.07; p < 0.05). Denial was associated with decreased CNC word (b = -0.04; 95% CI, -0.06 to -0.02; p < 0.01) and phoneme (b = -0.04; 95% CI, -0.07 to -0.02; p < 0.01) scores, whereas substance use was associated with increased CNC word (b = 0.03; 95% CI, 0.01 to 0.05, p < 0.01) and phoneme (b = 0.04; 95% CI, 0.02 to 0.06; p < 0.01) scores. Scores on self-reported quality of life measures were not significantly correlated with coping strategies. A variety of adaptive and maladaptive coping strategies are used by postlingually deaf adult cochlear implant users. Denial and acceptance may be more predictive of poor speech performance, whereas humor and substance use may be more predictive of improved speech performance.

Application of Signals with Rippled Spectra as a Training Approach for Speech Intelligibility Improvements in Cochlear Implant Users

In cochlear implant (CI) users, the discrimination of sound signals with rippled spectra correlates with speech discrimination. We suggest that rippled-spectrum signals could be a basis for training CI users to improve speech intelligibility. Fifteen CI users participated in the study. Ten of them used the software for training (the experimental group), and five did not (the control group). Software based on the phase reversal discrimination of rippled spectra was used. The experimental group was also tested for speech discrimination using phonetic material based on polysyllabic balanced speech material. An improvement in the discrimination of the rippled spectrum was observed in all CI users from the experimental group. There was no significant improvement in the control group. The result of the speech discrimination test showed that the percentage of recognized words increased after training in nine out of ten CI users. For five CI users who participated in the training program, the data on word recognition were also obtained earlier (at least eight months before training). The increase in the percentage of recognized words was greater after training compared to the period before training. The results allow the suggestion that sound signals with rippled spectra could be used not only for testing rehabilitation results after CI but also for training CI users to discriminate sounds with complex spectra.

Long-Term Binaural Hearing Improvements for Cochlear Implant Users with Asymmetric Hearing Loss.

To assess long-term binaural hearing abilities for cochlear implant (CI) users with unilateral hearing loss (UHL) or asymmetric hearing loss (AHL). A prospective, longitudinal, repeated measures study was completed at a tertiary referral center evaluating adults with UHL or AHL undergoing cochlear implantation. Binaural hearing abilities were assessed with masked speech recognition tasks using AzBio sentences in a 10-talker masker. Performance was evaluated as the ability to benefit from spatial release from masking (SRM). SRM was calculated as the difference in scores when the masker was presented toward the CI-ear (SRMci ) or the contralateral ear (SRMcontra ) relative to the co-located condition (0°). Assessments were completed pre-operatively and at annual intervals out to 5 years post-activation. Twenty UHL and 19 AHL participants were included in the study. Linear Mixed Models showed significant main effects of interval and group for SRMcontra . There was a significant interaction between interval and group, with UHL participants reaching asymptotic performance early and AHL participants demonstrating continued growth in binaural abilities to 5 years post-activation. The improvement in SRM showed a significant positive correlation with contralateral unaided hearing thresholds (p=0.050) as well as age at implantation (p=0.031). CI recipients with UHL and AHL showed improved SRM with long-term device use. The time course of improvement varied by cohort, with the UHL cohort reaching asymptotic performance early and the AHL cohort continuing to improve beyond 1 year. Differences between cohorts could be driven by differences in age at implantation as well as contralateral unaided hearing thresholds. 3 Laryngoscope, 133:1480-1485, 2023.

The Effects of Cortical Reorganization and Applications of Functional Near-Infrared Spectroscopy in Deaf People and Cochlear Implant Users.

A cochlear implant (CI) is currently the only FDA-approved biomedical device that can restore hearing for the majority of patients with severe-to-profound sensorineural hearing loss (SNHL). While prelingually and postlingually deaf individuals benefit substantially from CI, the outcomes after implantation vary greatly. Numerous studies have attempted to study the variables that affect CI outcomes, including the personal characteristics of CI candidates, environmental variables, and device-related variables. Up to 80% of the results remained unexplainable because all these variables could only roughly predict auditory performance with a CI. Brain structure/function differences after hearing deprivation, that is, cortical reorganization, has gradually attracted the attention of neuroscientists. The cross-modal reorganization in the auditory cortex following deafness is thought to be a key factor in the success of CI. In recent years, the adaptive and maladaptive effects of this reorganization on CI rehabilitation have been argued because the neural mechanisms of how this reorganization impacts CI learning and rehabilitation have not been revealed. Due to the lack of brain processes describing how this plasticity affects CI learning and rehabilitation, the adaptive and deleterious consequences of this reorganization on CI outcomes have recently been the subject of debate. This review describes the evidence for different roles of cross-modal reorganization in CI performance and attempts to explore the possible reasons. Additionally, understanding the core influencing mechanism requires taking into account the cortical changes from deafness to hearing restoration. However, methodological issues have restricted longitudinal research on cortical function in CI. Functional near-infrared spectroscopy (fNIRS) has been increasingly used for the study of brain function and language assessment in CI because of its unique advantages, which are considered to have great potential. Here, we review studies on auditory cortex reorganization in deaf patients and CI recipients, and then we try to illustrate the feasibility of fNIRS as a neuroimaging tool in predicting and assessing speech performance in CI recipients. Here, we review research on the cross-modal reorganization of the auditory cortex in deaf patients and CI recipients and seek to demonstrate the viability of using fNIRS as a neuroimaging technique to predict and evaluate speech function in CI recipients.

Reaching to Sounds Improves Spatial Hearing in Bilateral Cochlear Implant Users.

We assessed if spatial hearing training improves sound localization in bilateral cochlear implant (BCI) users and whether its benefits can generalize to untrained sound localization tasks. In 20 BCI users, we assessed the effects of two training procedures (spatial versus nonspatial control training) on two different tasks performed before and after training (head-pointing to sound and audiovisual attention orienting). In the spatial training, participants identified sound position by reaching toward the sound sources with their hand. In the nonspatial training, comparable reaching movements served to identify sound amplitude modulations. A crossover randomized design allowed comparison of training procedures within the same participants. Spontaneous head movements while listening to the sounds were allowed and tracked to correlate them with localization performance. During spatial training, BCI users reduced their sound localization errors in azimuth and adapted their spontaneous head movements as a function of sound eccentricity. These effects generalized to the head-pointing sound localization task, as revealed by greater reduction of sound localization error in azimuth and more accurate first head-orienting response, as compared to the control nonspatial training. BCI users benefited from auditory spatial cues for orienting visual attention, but the spatial training did not enhance this multisensory attention ability. Sound localization in BCI users improves with spatial reaching-to-sound training, with benefits to a nontrained sound localization task. These findings pave the way to novel rehabilitation procedures in clinical contexts.

Normative Cochlear Implant Quality of Life (CIQOL)-35 Profile and CIQOL-10 Global Scores for Experienced Cochlear Implant Users from a Multi-Institutional Study.

Although adult cochlear implant (CI) outcomes have primarily focused on speech recognition scores, the rigorous development of a CI-specific patient-reported outcome measure provides an opportunity for a more comprehensive and ecologically valid approach to measure the real-world functional abilities of adult CI users. Here, we report for the first time normative Cochlear Implant Quality of Life (CIQOL)-35 Profile and global scores and variance for a large, multi-institutional sample of adult CI users. Cross-sectional study design. CI centers in the United States. Seven hundred five adults with bilateral moderate to profound hearing loss with at least 1 year of CI use. Cochlear implantation. CIQOL-35 Profile and CIQOL-10 Global scores. During the development of the CIQOL instruments, 1,000 CI users from all regions of the United States were invited to participate in studies. Of these, 705 (70.5%) completed all portions of the study, and their data are reported here. Mean CIQOL domain scores were highest (indicating better function) for the emotional and social domains and lowest for listening effort. The entertainment and social domains demonstrated the widest distribution of scores and largest standard deviations, indicating greatest variability in function. Overall, there were minimal ceiling and floor effects for all domains. Normative scores from a large sample of experienced adult CI users are consistent with clinical observations, showing large differences in functional abilities and large variability. Normative CIQOL data for adult CI users have the potential to enhance preoperative discussions with CI candidates, improve post-CI activation monitoring, and establish standards for CI centers.

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.

A Study of Music Training for Cochlear Implant Users: Mismatch Negativity and Music Listening Attitude and Satisfaction Questionnaire

Purpose: The music rehabilitation program (MRP) promotes auditory, language, cognitive, and motor development of the brain. The significance of MRP was studied through mismatch negativity (MMN) and Music Listening Attitude and Satisfaction Questionnaire for hearing loss (MASQ_H). Methods: Fifteen adult cochlear implant (CI) users (34.5 years; standard deviation, ± 11.6) participated. MMN was tested before and after MRP training at the stimulus intensity level of 70 and 100 dB hearing loss (HL). In addition, MASQ_H was utilized. Results: For the pre- and post-tests of MMN, the average amplitudes of the waveforms were -2.48 ± 1.95 µV and -6.11 ± 4.21 µV and the areas were 208.16 ± 211.59 µV·ms and 527.87 ± 360.42 µV·ms with the significant difference when the stimulus level was presented at 70 dB HL. For MASQ_H, 90.9% of the participants responded that they felt satisfied with listening to music using CI or hearing aid. When asked about the musical factors that were improved in the music listening, the ‘pitch perception’ and ‘timbre perception’ were responded showing increased satisfaction rates. Conclusion: This study confirmed that MRP improved language processing by facilitating auditory processing, cognitive ability, and neural plasticity of the central auditory system through the increased amplitude and area of MMN after MRP application. Furthermore, providing a systematic music training such as MRP could change the music listening attitudes and satisfaction of the CI users’. The active implementation of music rehabilitation is strongly suggested.

The Impact of Vocal Boost Manipulations on Musical Sound Quality for Cochlear Implant Users.

To evaluate the impact of vocal boost manipulations on cochlear implant (CI) musical sound quality appraisals. An anonymous, online study was distributed to 33 CI users. Participants listened to auditory tokens and assessed the musical quality of acoustic stimuli with vocal boosting and attenuation using a validated sound quality rating scale. Four versions of real-world musical stimuli were created: a version with +9 dB vocal boost, a version with -9 dB vocal attenuation, a composite stimulus containing a 1,000 Hz low-pass filter and white noise ("anchor"), and an unaltered version ("hidden reference"). Subjects listened to all four versions and provided ratings based on a 100-point scale that reflected the perceived sound quality difference of the music clip relative to the reference excerpt. Vocal boost increased musical sound quality ratings relative to the reference clip (11.7; 95% CI, 1.62-21.8, p=0.016) and vocal attenuation decreased musical sound quality ratings relative to the reference clip (28.5; 95% CI, 18.64-38.44, p < 0.001). When comparing the non-musical training group and musical training group, there was a significant difference in musical sound quality rating scores for the vocal boost condition (21.2; 95% CI: 1.76-40.7, p=0.028). CI-mediated musical sound quality appraisals are impacted by vocal boost and attenuation. Musically trained CI users to report greater musical sound quality enhancement with a vocal boost with respect to CI users with no musical training background. Implementation of front-end vocal boost manipulations in music may improve sound quality and music appreciation among CI users. 2 (Individual cohort study) Laryngoscope, 133:938-947, 2023.

Masked Speech Recognition as a Function of Masker Location for Cochlear Implant Users With Single-Sided Deafness.

Cochlear implant (CI) recipients with normal or near normal hearing (NH) in the contralateral ear, referred to as single-sided deafness (SSD), experience significantly better speech recognition in noise with their CI than without it, although reported outcomes vary. One possible explanation for differences in outcomes across studies could be differences in the spatial configurations used to assess performance. This study compared speech recognition for different spatial configurations of the target and masker, with test materials used clinically. Sixteen CI users with SSD completed tasks of masked speech recognition presented in five spatial configurations. The target speech was presented from the front speaker (0° azimuth). The masker was located either 90° or 45° toward the CI-ear or NH-ear or colocated with the target. Materials were the AzBio sentences in a 10-talker masker and the Bamford-Kowal-Bench Speech-in-Noise test (BKB-SIN; four-talker masker). Spatial release from masking (SRM) was computed as the benefit associated with spatial separation relative to the colocated condition. Performance was significantly better when the masker was separated toward the CI-ear as compared to colocated. No benefit was observed for spatial separations toward the NH-ear. The magnitude of SRM for spatial separations toward the CI-ear was similar for 45° and 90° when tested with the AzBio sentences, but a larger benefit was observed for 90° as compared to 45° for the BKB-SIN. Masked speech recognition in CI users with SSD varies as a function of the spatial configuration of the target and masker. Results supported an expansion of the clinical test battery at the study site to assess binaural hearing abilities for CI candidates and recipients with SSD. The revised test battery presents the target from the front speaker and the masker colocated with the target, 90° toward the CI-ear, or 90° toward the NH-ear.

Combining Place and Rate of Stimulation Improves Frequency Discrimination in Cochlear Implant Users

In the auditory system, frequency is represented as tonotopic and temporal response properties of the auditory nerve. While these response properties are inextricably linked in normal hearing, cochlear implants can separately excite tonotopic location and temporal synchrony using different electrodes and stimulation rates, respectively. This separation allows for the investigation of the contributions of tonotopic and temporal cues for frequency discrimination. The present study examines frequency discrimination in adult cochlear implant users as conveyed by electrode position and stimulation rate, separately and combined. The working hypothesis is that frequency discrimination is better provided by place and rate cues combined compared to either cue alone. This hypothesis was tested in two experiments. In the first experiment, frequency discrimination needed for melodic contour identification was measured for frequencies near 100, 200, and 400 Hz using frequency allocation modeled after clinical processors. In the second experiment, frequency discrimination for pitch ranking was measured for frequencies between 100 and 1600 Hz using an experimental frequency allocation designed to provide better access to place cues. The results of both experiments indicate that frequency discrimination is better with place and rate cues combined than with either cue alone. These results clarify how signal processing for cochlear implants could better encode frequency into place and rate of electrical stimulation. Further, the results provide insight into the contributions of place and rate cues for pitch.

Thermal Characteristics of Different Types of Cochlear Implants in Pediatric Cochlear Implant Users: AComparative Digital-Infrared Thermal Imaging Analysis.

Background:This study aimed to evaluate thermal characteristics of different types of pediatric cochlear implantsMethods:A total of 39 pediatric patients using Med-El (Synchrony®), Cochlear (Nucleus®), or Advanced Bionics (HiRes 90K®) type of cochlear implants were included. A digital infrared thermal imaging analysis was performed to measure the heating over the implant and the tissue heating of the skin below and around the device, while skin thickness and visual analog scale scores were also recorded.Results:Over the implant, heating values were significantly higher in the on-mode vs. off-mode of device for each type of implant (P ranged from <.05 to <.001). The implants groups were similar in terms of skin thickness, visual analog scale scores, on-mode values for heating over the implant, and the heating of the skin (below or around the device; <36°C for each), while the off-mode values for heating over the implant were significantly higher in the Med-El (Synchrony®) implants compared to other implants (median 31.75 vs. 31.30 and 30.20°C, P = .001). Skin thickness was negatively correlated with the heating over the implant (off-mode, r = −0.708, P < .001) and heating of the skin (around the device, r = −0.479, P = .028) in Advanced Bionics (HiRes 90K®) implants.Conclusion:Our findings emphasize that there is no hazard or discomfort from a cochlear implant in terms of heating of skin and no significant difference between 3 implant types in terms of skin thickness or tissue heating, whereas indicate the increased likelihood of thermal characteristics of implant to differ with respect to skin thickness in Advanced Bionics (HiRes 90K®) users.

Cortical Entrainment to Speech Produced by Cochlear Implant Users and Normal-Hearing Talkers.

The perceived sound quality of speech produced by hard-of-hearing individuals greatly depends on the degree and configuration of their hearing loss. A cochlear implant (CI) may provide some compensation and auditory feedback to monitor/control speech production. However, to date, the speech produced by CI users is still different in quality from that produced by normal-hearing (NH) talkers. In this study, we attempted to address this difference by examining the cortical activity of NH listeners when listening to continuous speech produced by 8 CI talkers and 8 NH talkers. We utilized a discriminative model to decode and reconstruct the speech envelope from the single-trial electroencephalogram (EEG) recorded from scalp electrode in NH listeners when listening to continuous speech. The correlation coefficient between the reconstructed envelope and original speech envelope was computed as a metric to quantify the difference in response to the speech produced by CI and NH talkers. The same listeners were asked to rate the perceived sound quality of the speech as a behavioral sound quality assessment. Both behavioral perceived sound quality ratings and the cortical entrainment to speech envelope were higher for the speech set produced by NH talkers than for the speech set produced by CI talkers.