Bilateral Cochlear Implants Group Research Articles

Factors associated with nonword repetition skills in 4-to 6-year-old deaf and hard-of-hearing and typically hearing children

ABSTRACT Children identified as deaf and hard of hearing (DHH) exhibit an increased risk of speech and language difficulties. Nonword repetition (NWR) is a potential tool for identifying language difficulties in children with limited experience with the target language. In this study, we explored associations between auditory, linguistic, demographic and cognitive factors and NWR performance in DHH children and their typically hearing (TH) peers. We also examined the effect of the group on NWR outcomes when different factors were statistically controlled for. Our study included 68 4- to 6-year-old children: 18 with bilateral hearing aids (BiHAs), 18 with bilateral cochlear implants (BiCIs) and 32 with TH. The participants completed the Finnish Nonword Repetition Test comprising 24 test items with varying syllable lengths. The assessment methods also included tests of phonological, lexical, language comprehension and sentence repetition skills, along with a measure of nonverbal intelligence. The results showed that none of the auditory, linguistic, demographic and cognitive factors examined in the present study were correlated with NWR performance in the BiHA group, while significant correlations between NWR skills and linguistic abilities were observed in the BiCI group. The DHH children showed extraordinary difficulties in NWR compared to their TH peers, and these group differences remained after controlling for linguistic and demographic variables. The NWR task may be a potential clinical tool for identifying DHH children at risk for poor language outcomes and in need of speech and language intervention.

Parental Contingent Verbal Response to Early Vocalizations of Simultaneous Bilateral Cochlear Implantees

Objectives: The parental verbal response greatly influences infants’ speech-language development in early communication. This study aimed to investigate the features of parental verbal responses in infants who have undergone simultaneous bilateral cochlear implantation compared to chronological age-matched (CA) and hearing age-matched (HA) children who have typical hearing.Methods: Thirteen pairs of infants with cochlear implants (CIs) and their parents, 13 pairs of CA infants and their parents, and 13 pairs of HA infants and their parents participated in this study. The parent-infant interaction task was conducted in a free-play situation. Infants’ vocalizations were classified into canonical and non-canonical vocalizations. Parental verbal responses were divided into parental contingent responses (PCRs), parental non-contingent responses (PNCRs), and no response (NR). PCRs were divided into the language expectant and language non-expectant responses.Results: There was no significant difference in the ratio of parental verbal responses between the three groups. The ratio of parental verbal responses to non-canonical vocalizations was higher than parental verbal responses to canonical vocalizations. Additionally, the ratio of PCRs was higher than that of PNCRs and NR, and the ratio of language expectant responses was higher than that of language non-expectant responses. However, the ratio of language development responses to non-canonical vocalizations is similar to that of canonical vocalizations in the CI group.Conclusion: Parents of the simultaneous bilateral CI group tend to respond quickly and sensitively to the vocalization of infants’ vocalizations. Parents in the CI group can adjust their language based on their infant’s vocalization and development. These findings can guide early intervention and coaching for parents of infants with CIs.

Validation of the Norwegian Version of the Speech, Spatial and Qualities of Hearing Scale (SSQ)

Introduction: The main objective of the study was to validate the Norwegian translation of the Speech, Spatial and Qualities of Hearing Scale (SSQ) and investigate the SSQ disability profiles in a cochlear implant (CI) user population. Methods: The study involved 152 adult CI users. The mean age at implantation was 55 (standard deviation [SD] = 16), and the mean CI experience was 5 years (SD = 4.8). The cohort was split into three groups depending on the hearing modality: bilateral CIs (BCIs), a unilateral CI (UCI), and bimodal (CI plus contralateral hearing aid; HCI). The SSQ disability profiles of each group were compared with those observed in similar studies using the English version and other translations of the SSQ. Standard values, internal consistency, sensitivity, and floor and ceiling effects were investigated, and the missing-response rates to specific questions were calculated. Relationships to speech perception were measured using monosyllabic word scores and the Norwegian Hearing in Noise Test scores. Results: In the BCI group, the average scores were around 5.0 for the speech and spatial sections and 7.0 for the qualities section (SD ∼2). The average scores of the UCI and HCI groups were about one point lower than those of the BCI group. The SSQ disability profiles were comparable to the profiles in similar studies. The slopes of the linear regression lines measuring the relationships between the SSQ speech and monosyllabic word scores were 0.8 per 10% increase in the monosyllabic word score for the BCI group (explaining 35% of the variation) and 0.4 for the UCI and HCI groups (explaining 22–23% of the variation). Conclusion: The Norwegian version of the SSQ measures hearing disability similar to the original English version, and the internal consistency is good. Differences in the recipients’ pre-implantation variables could explain some variations we observed in the SSQ responses, and such predictors should be investigated. Data aggregation will be possible using the SSQ as a routine clinical assessment in global CI populations. Moreover, pre-implantation variables should be systematically registered so that they can be used in mixed-effects models.

Effect of cochlear implantation on speech recognition under different listening modes in children

Objective:To investigate speech recognition among children with a unilateral cochlear implant（CI）, bilateral CI, and bimodal hearing and identify the benefits of binaural hearing. Methods:A total of 67 children with severe sensorineural hearing loss who received bilateral CI, bimodal hearing, and unilateral CI from 2012 to 2021 were recruited, including 23 cases with unilateral CI, 25 cases of bimodal hearing, and 19 cases of bilateral CI. The aided hearing threshold at 250-4000 Hz and speech recognition performance of two-syllable words and short sentences in quiet and noisy environments were tested, respectively. Results:There was no significant difference in the hearing threshold results of the bilateral CI group, the bimodal hearing group, and the unilateral CI group by ANOVA（P>0.05）. According to the paired t-test within the group, the speech recognition of disyllabic words and short sentences in quiet and noisy environments were significantly different among the three groups（P<0.05）. There was no significant difference in the speech recognition rates of disyllabic words and short sentences among the three groups in a quiet environment（P>0.05）, but there was a statistically significant difference in a noisy environment（P<0.05）. Additional multiple linear regression analysis showed no significant difference in the recognition rates of disyllabic words and short sentences between the bimodal group and the bilateral CI group in quiet and noisy environments（β=-0.567, P>0.05; β=-0.643, P>0.05）. There was a statistically significant difference in speech recognition of disyllabic words and short sentences between the bimodal group and the unilateral CI group in the noise environment（β=-0.124, P<0.05）, but the difference was not statistically significant in a quiet environment（β=-0.671, P>0.05）; there was a statistically significant difference in the recognition rate of disyllabic words and short sentences between the bilateral CI group and the unilateral CI group in the noise environment（β=-0.226, P<0.05）, but the difference was not statistically significant in a quiet environment（β=-0.341, P>0.05）. Conclusion:Clinicians and guardians are encouraged to provide the most comprehensive audiological evaluation for children with hearing loss. Bilateral CI and bimodal hearing have demonstrated enormous advantages over unilateral CI regarding speech recognition in noise. Bimodal hearing deems a strong recommendation if the contralateral ear has sufficient speech recognition capability. Bilateral CI should be warranted if hearing aids deemed to be ineffective.

School adjustment of adolescents with sequential bilateral cochlear implants in mainstream school.

Little is known about the school adjustment of adolescents with sequential bilateral cochlear implants (CIs) in mainstream educational settings. This study aims to investigate the school adjustment of adolescents with sequential bilateral CIs, in comparison to those of age-matched adolescents with typical hearing (TH), to explore the relationships between individual variables and school adjustment in the bilateral CI group, and to assess the factors leading to strong school adjustment in the bilateral CI group. Twenty-five adolescents with sequential bilateral CIs and 30 adolescents with TH, aged 13-19 years, participated in this study. The adolescents completed the school adjustment scale (SAS). The two groups were not significantly different on overall SAS scores. However, the TH group scored higher on the SAS than the sequential bilateral CI group with regard to communication skills and relationships with peers. In the bilateral CI group, SAS scores significantly correlated with open-set sentence and receptive vocabulary scores. Receptive vocabulary scores were a significant predictive factor for the level of school adjustment for the bilateral CI group. Adolescents who received sequential bilateral CIs adapted well to mainstream schools. However, they did experience barriers to communication and to make friends in mainstream schools, and their level of school adjustment was affected by their receptive vocabulary skills.

Differential Effects of Binaural Pitch Fusion Range on the Benefits of Voice Gender Differences in a "Cocktail Party" Environment for Bimodal and Bilateral Cochlear Implant Users.

Some cochlear implant (CI) users are fitted with a CI in each ear ("bilateral"), while others have a CI in one ear and a hearing aid in the other ("bimodal"). Presently, evaluation of the benefits of bilateral or bimodal CI fitting does not take into account the integration of frequency information across the ears. This study tests the hypothesis that CI listeners, especially bimodal CI users, with a more precise integration of frequency information across ears ("sharp binaural pitch fusion") will derive greater benefit from voice gender differences in a multi-talker listening environment. Twelve bimodal CI users and twelve bilateral CI users participated. First, binaural pitch fusion ranges were measured using the simultaneous, dichotic presentation of reference and comparison stimuli (electric pulse trains for CI ears and acoustic tones for HA ears) in opposite ears, with reference stimuli fixed and comparison stimuli varied in frequency/electrode to find the range perceived as a single sound. Direct electrical stimulation was used in implanted ears through the research interface, which allowed selective stimulation of one electrode at a time, and acoustic stimulation was used in the non-implanted ears through the headphone. Second, speech-on-speech masking performance was measured to estimate masking release by voice gender difference between target and maskers (VGRM). The VGRM was calculated as the difference in speech recognition thresholds of target sounds in the presence of same-gender or different-gender maskers. Voice gender differences between target and masker talkers improved speech recognition performance for the bimodal CI group, but not the bilateral CI group. The bimodal CI users who benefited the most from voice gender differences were those who had the narrowest range of acoustic frequencies that fused into a single sound with stimulation from a single electrode from the CI in the opposite ear. There was no similar voice gender difference benefit of narrow binaural fusion range for the bilateral CI users. The findings suggest that broad binaural fusion reduces the acoustical information available for differentiating individual talkers in bimodal CI users, but not for bilateral CI users. In addition, for bimodal CI users with narrow binaural fusion who benefit from voice gender differences, bilateral implantation could lead to a loss of that benefit and impair their ability to selectively attend to one talker in the presence of multiple competing talkers. The results suggest that binaural pitch fusion, along with an assessment of residual hearing and other factors, could be important for assessing bimodal and bilateral CI users.

Investigating Bilateral Cochlear Implant Users' Localization of Amplitude- and Time-Panned Stimuli Produced Over a Limited Loudspeaker Arrangement.

The objective of this study was to investigate the localization ability of bilateral cochlear implant (BiCI) users for virtual sound sources produced over a limited loudspeaker arrangement. Ten BiCI users and 10 normal-hearing subjects participated in listening tests in which amplitude- and time-panned virtual sound sources were produced over a limited loudspeaker setup with varying azimuth angles. Three stimuli were utilized: speech, bandpassed pink noise between 20 Hz and 1 kHz, and bandpassed pink noise between 1 kHz and 8 kHz. The data were collected via a two-alternative forced-choice procedure and used to calculate the minimum audible angle (MAA) of each subject, which was subsequently compared to the results of previous studies in which real sound sources were employed. The median MAAs of the amplitude-panned speech, low-frequency pink noise, and high-frequency pink noise stimuli for the BiCI group were calculated to be 20°, 38°, and 12°, respectively. For the time-panned stimuli, the MAAs of the BiCI group for all three stimuli were calculated to be close to the upper limit of the listening test. The computed MAAs of the BiCI group for amplitude-panned speech were marginally larger than BiCI users' previously reported MAAs for real sound sources, whereas their computed MAAs for the time-panned stimuli were significantly larger. Subsequent statistical analysis indicated a statistically significant difference in the performances of the BiCI group in localizing the amplitude-panned sources and the time-panned sources. It follows that time-panning over limited loudspeaker arrangements may not be a useful clinical tool, whereas amplitude-panning utilizing such a setup may be further explored as such. Additionally, a comparison with the patient demographics indicated correlations between the results and the patients' age at time of diagnoses and the time passed between date of diagnosis and their implant surgeries.

Spatial Hearing Difficulties in Reaching Space in Bilateral Cochlear Implant Children Improve With Head Movements.

The aim of this study was to assess three-dimensional (3D) spatial hearing abilities in reaching space of children and adolescents fitted with bilateral cochlear implants (BCI). The study also investigated the impact of spontaneous head movements on sound localization abilities. BCI children (N = 18, aged between 8 and 17) and age-matched normal-hearing (NH) controls (N = 18) took part in the study. Tests were performed using immersive virtual reality equipment that allowed control over visual information and initial eye position, as well as real-time 3D motion tracking of head and hand position with subcentimeter accuracy. The experiment exploited these technical features to achieve trial-by-trial exact positioning in head-centered coordinates of a single loudspeaker used for real, near-field sound delivery, which was reproducible across trials and participants. Using this novel approach, broadband sounds were delivered at different azimuths within the participants' arm length, in front and back space, at two different distances from their heads. Continuous head-monitoring allowed us to compare two listening conditions: "head immobile" (no head movements allowed) and "head moving" (spontaneous head movements allowed). Sound localization performance was assessed by computing the mean 3D error (i.e. the difference in space between the X-Y-Z position of the loudspeaker and the participant's final hand position used to indicate the localization of the sound's source), as well as the percentage of front-back and left-right confusions in azimuth, and the discriminability between two nearby distances. Several clinical factors (i.e. age at test, interimplant interval, and duration of binaural experience) were also correlated with the mean 3D error. Finally, the Speech Spatial and Qualities of Hearing Scale was administered to BCI participants and their parents. Although BCI participants distinguished well between left and right sound sources, near-field spatial hearing remained challenging, particularly under the " head immobile" condition. Without visual priors of the sound position, response accuracy was lower than that of their NH peers, as evidenced by the mean 3D error (BCI: 55 cm, NH: 24 cm, p = 0.008). The BCI group mainly pointed along the interaural axis, corresponding to the position of their CI microphones. This led to important front-back confusions (44.6%). Distance discrimination also remained challenging for BCI users, mostly due to sound compression applied by their processor. Notably, BCI users benefitted from head movements under the "head moving" condition, with a significant decrease of the 3D error when pointing to front targets (p < 0.001). Interimplant interval was correlated with 3D error (p < 0.001), whereas no correlation with self-assessment of spatial hearing difficulties emerged (p = 0.9). In reaching space, BCI children and adolescents are able to extract enough auditory cues to discriminate sound side. However, without any visual cues or spontaneous head movements during sound emission, their localization abilities are substantially impaired for front-back and distance discrimination. Exploring the environment with head movements was a valuable strategy for improving sound localization within individuals with different clinical backgrounds. These novel findings could prompt new perspectives to better understand sound localization maturation in BCI children, and more broadly in patients with hearing loss.

Are There Real-world Benefits to Bimodal Listening?

To assess the benefits of bimodal listening (i.e., addition of contralateral hearing aid) for cochlear implant (CI) users on real-world tasks involving high-talker variability speech materials, environmental sounds, and self-reported quality of life (quality of hearing) in listeners' own best-aided conditions. Cross-sectional study between groups. Outpatient hearing clinic. Fifty experienced adult CI users divided into groups based on normal daily listening conditions (i.e., best-aided conditions): unilateral CI (CI), unilateral CI with contralateral HA (bimodal listening; CIHA), or bilateral CI (CICI). Task-specific measures of speech recognition with low (Harvard Standard Sentences) and high (Perceptually Robust English Sentence Test Open-set corpus) talker variability, environmental sound recognition (Familiar Environmental Sounds Test-Identification), and hearing-related quality of life (Nijmegen Cochlear Implant Questionnaire). Test group differences among CI, CIHA, and CICI conditions. No group effect was observed for speech recognition with low or high-talker variability, or hearing-related quality of life. Bimodal listeners demonstrated a benefit in environmental sound recognition compared with unilateral CI listeners, with a trend of greater benefit than the bilateral CI group. There was also a visual trend for benefit on high-talker variability speech recognition. Findings provide evidence that bimodal listeners demonstrate stronger environmental sound recognition compared with unilateral CI listeners, and support the idea that there are additional advantages to bimodal listening after implantation other than speech recognition measures, which are at risk of being lost if considering bilateral implantation.

Sound Localization in Toddlers with Normal Hearing and with Bilateral Cochlear Implants Revealed Through a Novel "Reaching for Sound" Task.

Spatial hearing abilities in children with bilateral cochlear implants (BiCIs) are typically improved when two implants are used compared with a single implant. However, even with BiCIs, spatial hearing is still worse compared to normal-hearing (NH) age-matched children. Here, we focused on children who were younger than three years, hence in their toddler years. Prior research with this age focused on measuring discrimination of sounds from the right versus left. This study measured both discrimination and sound location identification in a nine-alternative forced-choice paradigm using the "reaching for sound" method, whereby children reached for sounding objects as a means of capturing their spatial hearing abilities. Discrimination was measured with sounds randomly presented to the left versus right, and loudspeakers at fixed angles ranging from ±60° to ±15°. On a separate task, sound location identification was measured for locations ranging from ±60° in 15° increments. Thirteen children with BiCIs (27-42 months old) and fifteen age-matched (NH). Discrimination and sound localization were completed for all subjects. For the left-right discrimination task, participants were required to reach a criterion of 4/5 correct trials (80%) at each angular separation prior to beginning the localization task. For sound localization, data was analyzed in two ways. First, percent correct scores were tallied for each participant. Second, for each participant, the root-mean-square-error was calculated to determine the average distance between the response and stimulus, indicative of localization accuracy. All BiCI users were able to discriminate left versus right at angles as small as ±15° when listening with two implants; however, performance was significantly worse when listening with a single implant. All NH toddlers also had >80% correct at ±15°. Sound localization results revealed root-mean-square errors averaging 11.15° in NH toddlers. Children in the BiCI group were generally unable to identify source location on this complex task (average error 37.03°). Although some toddlers with BiCIs are able to localize sound in a manner consistent with NH toddlers, for the majority of toddlers with BiCIs, sound localization abilities are still emerging.

A functionally relevant measure of spatial release from masking in children with bilateral cochlear implants

The ability to segregate speech from noise is an important skill for children as they navigate everyday noisy environments. Spatial release from masking (SRM) is a measure of benefit observed when target speech is co-located versus spatially separated from maskers. SRM is typically studied with target-maskers in front versus maskers displaced to fixed angles towards the side. Children fitted with bilateral cochlear implants (BiCIs) typically show smaller SRM than children with normal hearing (NH), even for target-masker angular separation of 90°, and when monaural head shadow cues exist. Here, we used an open-set corpus that has high informational masking and better mimics realistic listening situations for children. First, SRM was measured by adapting target-masker separation, and quantified as the minimal angular separation needed to achieve 20% improvement in target intelligibility. Second, SRM was measured for target-masker separation of 180°. Preliminary results suggested that, in the BiCI group, all children achieved 20% SRM with a target-masker angular separation smaller than 180°. With the full 180° target-masker separation, children in the BiCI group achieved a much larger SRM (6–8 dB) than previously reported while NH children’s SRM was larger. Acoustic cues available through CI processors will be discussed. [Work funded by NIH-NIDCD.]

Early auditory skills development in Mandarin speaking children after bilateral cochlear implantation

ObjectivesThe purpose of the present study was: (1) to investigate the early auditory preverbal behaviors of infants/toddlers with bilateral cochlear implants (BCI), and to compare their performance with that of unilateral cochlear implant (UCI) peers; (2) to investigate effects of age of implantation, education level of caregivers, living environment, and unaided behavioral threshold before operation on early auditory preverbal development. MethodsThe evaluation material of the present study was the Mandarin version of the LittlEARS® Auditory Questionnaire (LEAQ). Assessments were administrated at 0, 1, 2, 3, 6, 9, 12 and 24 months after cochlear implants (CIs) were switched on. A one-way ANOVA was used to analyze the differences of early auditory preverbal performance between each two contiguous test intervals. A two-sample t-test was used to analyze the difference of behaviors between infants/toddlers with BCI and UCI. Non-parametric tests were used to analyze the effects of potential affecting factors on auditory preverbal skills. ResultsNineteen subjects aging from 9 to 54 months (Mean = 22.7, SD = 13.7) were recruited in the study. At each evaluation time, the average scores of LEAQ were 4.58, 9.00, 16.00, 18.56, 22.00, 31.50, 29.67, and 34.35 respectively. The total score and semantic auditory behavior score increased significantly during the second months after CIs activation (the total score: LSD-t = 3.157, p = 0.030; semantic auditory behavior score: LSD-t = 1.972, p = 0.034). The score of BCI group was significantly higher than UCI group after 1, 3 and 6 months of CI use (1 month: t = 3.257, p = 0.002; 3 months: t = 5.042, p = 0.000; 6 months: t = 4.054, p = 0.000). Education level of caregivers had a positive effect on receptive auditory behavior (H = 6.538, p = 0.035) after CIs switched on for 3 months. The LEAQ performance was not significantly correlated with pre-operative behavioral threshold although they showed a trend of negative correlation in the first 3 months after activation. ConclusionThe study indicated that infants and toddlers who underwent BCI had better auditory preverbal skills than their UCI peers. Higher caregivers' education level positively correlated with the early development of auditory preverbal skills. Better pre-operative behavioral threshold might also benefit early auditory preverbal skills development for BCI children.

A long term effect on speech recognition in the patients with simultaneous bilateral cochlear implants

Objective: To investigate an effect on speech recognition after bilateral cochlear implants(CI) simultaneously. Methods: Nine subjects who underwent bilateral CI operation simultaneously in Peking Union Hospital in 2007 were assigned as bilateral group, another 9 subjects with unilateral CI were chosen as unilateral group according to the age, gender, duration of deafness. Hearing threshold, speech recognition of phrases, disyllabic words, single word in quiet and noise environment were calculated, respectively. Three different sound source positions were set up to simulate the three effects of binaural hearing (head shadow, binaural redundancy and binaural squelch) in noise environment. The speech signal intensity was 70 dBSPL, the signal to noise ratio (SNR) was 0 dB, + 4 dB, + 8 dB, and the speech recognition of phrases were examined in bilateral CI group. All the data was analyzed by SPSS 19.0 software. Results: In quiet environment, the average aid-hearing threshold was significantly reduced as (7.2±3.0)dB in bilateral CI group compared to unilateral CI group(P<0.05). However, the speech recognition of phrases, disyllabic words, and single word in quiet and noise environment did not show significant differences between bilateral CI and unilateral CI groups (P>0.05). In the testing under noise environment, the speech recognition of bilateral CI group was significantly higher than that of unilateral CI group (P<0.05). In the estimation of noise environment (SNR=+ 8), the phrase test and speech recognition of head shadow model in bilateral groups were significantly better than that of unilateral group (P<0.01). Further, bilateral CI group showed statistical significances in binaural redundancy and binaural squelch models(P<0.01), there was statistically significant were also found difference between two groups (P<0.01); Bilateral CI group did not reveal significant difference compared with unbilateral CI group in binaural squelch model(P>0.05). Under different signal-to-noise ratio (SNR=+ 8, + 4) noise environment, all the three given models in bilateral CI group show higher signal-to-noise ratio, higher speech recognition rate (Independent-Samples t test, P<0.01). In addition, head shadow model presented negative influences on speech recognition rate compared with binaural redundancy and binaural squelch model by SNR(P<0.05). SNR influences on binaural redundancy and binaural squelch model were almost identical, F=0.371, P=0.549. Conclusion: The subjects who underwent simultaneous bilateral cochlear implantation could significantly reduce aid-hearing threshold, and greatly improve the speech recognition of phrases, disyllabic words, and single word under noise environment.

Spatial Release From Masking in 2-Year-Olds With Normal Hearing and With Bilateral Cochlear Implants.

This study evaluated spatial release from masking (SRM) in 2- to 3-year-old children who are deaf and were implanted with bilateral cochlear implants (BiCIs), and in age-matched normal-hearing (NH) toddlers. Here, we examined whether early activation of bilateral hearing has the potential to promote SRM that is similar to age-matched NH children. Listeners were 13 NH toddlers and 13 toddlers with BiCIs, ages 27 to 36 months. Speech reception thresholds (SRTs) were measured for target speech in front (0°) and for competitors that were either Colocated in front (0°) or Separated toward the right (+90°). SRM was computed as the difference between SRTs in the front versus in the asymmetrical condition. Results show that SRTs were higher in the BiCI than NH group in all conditions. Both groups had higher SRTs in the Colocated and Separated conditions compared with Quiet, indicating masking. SRM was significant only in the NH group. In the BiCI group, the group effect of SRM was not significant, likely limited by the small sample size; however, all but two children had SRM values within the NH range. This work shows that to some extent, the ability to use spatial cues for source segregation develops by age 2 to 3 in NH children and is attainable in most of the children in the BiCI group. There is potential for the paradigm used here to be used in clinical settings to evaluate outcomes of bilateral hearing in very young children.

Effectiveness of Directional Microphones in Bilateral/Bimodal Cochlear Implant Users-Impact of Spatial and Temporal Noise Characteristics.

To measure speech reception thresholds (SRTs) in co-located (S0N0) and diffuse noise conditions (multi-source noise field, MSNF) and to assess the impact of beamforming algorithms in MSNF in cochlear implant (CI) users. Non-randomized, open, prospective study. Tertiary referral cochlear implantation center. Participants included 14 CI users (7 bimodal, 7 bilateral) and 14 normal hearing young adults. Cochlear implantation. SRTs were assessed by means of a German matrix sentence test in either continuous or modulated noise. Loudspeakers were configured in two different conditions: S0N0 and MSNF (speech source in front, four speakers distributed at ±28.6 and ±151.4 degrees). In MSNF, the CI speech processor microphone was set in different directional sensitivity settings: standard (sub-cardioid), fixed (super-cardioid), and adaptive. In continuous noise, SRTs of both CI groups were comparable. In modulated noise, bimodal CI users showed lower SRTs than bilateral CI group, but significant benefit from glimpsing was only demonstrated in normal hearing participants. All subject groups showed significant spatial release from masking (i.e., SRT improvement in MSNF compared with S0N0 condition) in continuous noise. A tendency of improved SRT (1 dB bimodal, 2 dB bilateral) with fixed and adaptive directional sensitivity was found which could not be statistically confirmed due to large between-subject variations. The absence of the glimpsing effect in CI users was reaffirmed in the present study. Although very effective in single noise source conditions, the beneficial impact of beamforming algorithms in multiple noise source conditions is poor.

Objective and Subjective Measures of Simultaneous vs Sequential Bilateral Cochlear Implants in Adults

ImportanceTo date, no randomized clinical trial on the comparison between simultaneous and sequential bilateral cochlear implants (BiCIs) has been performed.ObjectiveTo investigate the hearing capabilities and the self-reported benefits of simultaneous BiCIs compared with those of sequential BiCIs.Design, Setting, and ParticipantsA multicenter randomized clinical trial was conducted between January 12, 2010, and September 2, 2012, at 5 tertiary referral centers among 40 participants eligible for BiCIs. Main inclusion criteria were postlingual severe to profound hearing loss, age 18 to 70 years, and a maximum duration of 10 years without hearing aid use in both ears. Data analysis was conducted from May 24 to June 12, 2016.InterventionsThe simultaneous BiCI group received 2 cochlear implants during 1 surgical procedure. The sequential BiCI group received 2 cochlear implants with an interval of 2 years between implants.Main Outcomes and MeasuresFirst, the results 1 year after receiving simultaneous BiCIs were compared with the results 1 year after receiving sequential BiCIs. Second, the results of 3 years of follow-up for both groups were compared separately. The primary outcome measure was speech intelligibility in noise from straight ahead. Secondary outcome measures were speech intelligibility in noise from spatially separated sources, speech intelligibility in silence, localization capabilities, and self-reported benefits assessed with various hearing and quality of life questionnaires.ResultsNineteen participants were randomized to receive simultaneous BiCIs (11 women and 8 men; median age, 52 years [interquartile range, 36-63 years]), and another 19 participants were randomized to undergo sequential BiCIs (8 women and 11 men; median age, 54 years [interquartile range, 43-64 years]). Three patients did not receive a second cochlear implant and were unavailable for follow-up. Comparable results were found 1 year after simultaneous or sequential BiCIs for speech intelligibility in noise from straight ahead (difference, 0.9 dB [95% CI, –3.1 to 4.4 dB]) and all secondary outcome measures except for localization with a 30° angle between loudspeakers (difference, –10% [95% CI, –20.1% to 0.0%]). In the sequential BiCI group, all participants performed significantly better after the BiCIs on speech intelligibility in noise from spatially separated sources and on all localization tests, which was consistent with most of the participants’ self-reported hearing capabilities. Speech intelligibility-in-noise results improved in the simultaneous BiCI group up to 3 years following the BiCIs.Conclusions and RelevanceThis study shows comparable objective and subjective hearing results 1 year after receiving simultaneous BiCIs and sequential BiCIs with an interval of 2 years between implants. It also shows a significant benefit of sequential BiCIs over a unilateral cochlear implant. Until 3 years after receiving simultaneous BiCIs, speech intelligibility in noise significantly improved compared with previous years.Trial Registrationtrialregister.nl Identifier: NTR1722

Functional Listening Performance of Children with Sequential Bilateral Cochlear Implantation in Daily Life

Received November 13, 2014 Revised December 22, 2014 Accepted January 2, 2015 Address for correspondence Yun-Hoon Choung, MD, DDS, PhD Department of Otolaryngology, Ajou University School of Medicine, 164 World cup-ro, Yeongtong-gu, Suwon 443-380, Korea Tel +82-31-219-5263 Fax +82-31-219-5264 E-mail yhc@ajou.ac.kr Background and ObjectivesZZThis study aims to identify whether the sequential bilateral cochlear implantation in children with a long inter-implant interval provides functional benefits in everyday situation. Subjects and MethodZZSeventeen children with sequential bilateral cochlear implants (BiCIs) (mean age at first implantation, 2.6 years; mean age at second implantation, 8.5 years; mean inter-implant interval, 6.0 years) and 17 children with unilateral cochlear implants (UniCIs) were included in this study. The questionnaire SSQ (The Speech, Spatial, and Qualities of hearing scale for parents of children with impaired hearing, Galvin, 2007) was used to evaluate the performance of two groups by individually interviewing the parents of the subjects. For the BiCIs, anecdotal reports of the performance in everyday listening situation and device use were also collected in interviews. ResultsZZThe BiCI group showed significantly better performance in all three areas (speech perception, spatial hearing, and other qualities of hearing) of the SSQ than did the UniCI group. The differences between the two groups were significantly larger in performance on ‘spatial hearing’ and ‘other qualities of hearing’ than on ‘speech perception’. All subjects with bilateral cochlear implants had a positive attitude on bilateral hearing. Anecdotal reports indicated that bilateral hearing has positive effects such as reduced repeated questions, increased participation in conversation, facilitated language and learning acquisition, and improved concentration. ConclusionZZChildren who received sequential bilateral cochlear implantation with a long inter-implant interval could obtain functional benefits in daily life. Also it turned out that these benefits have positive effects on children’s communication, language, learning, and socio-emotional areas. Korean J Otorhinolaryngol-Head Neck Surg 2015;58(7):463-8

Speech Perception With Combined Electric-Acoustic Stimulation and Bilateral Cochlear Implants in a Multisource Noise Field

The aim of the study was to measure and compare speech perception in users of electric-acoustic stimulation (EAS) supported by a hearing aid in the unimplanted ear and in bilateral cochlear implant (CI) users under different noise and sound field conditions. Gap listening was assessed by comparing performance in unmodulated and modulated Comité Consultatif International Téléphonique et Télégraphique (CCITT) noise conditions, and binaural interaction was investigated by comparing single source and multisource sound fields. Speech perception in noise was measured using a closed-set sentence test (Oldenburg Sentence Test, OLSA) in a multisource noise field (MSNF) consisting of a four-loudspeaker array with independent noise sources and a single source in frontal position (S0N0). Speech simulating noise (Fastl-noise), CCITT-noise (continuous), and OLSA-noise (pseudo continuous) served as noise sources with different temporal patterns. Speech tests were performed in two groups of subjects who were using either EAS (n = 12) or bilateral CIs (n = 10). All subjects in the EAS group were fitted with a high-power hearing aid in the opposite ear (bimodal EAS). The average group score on monosyllable in quiet was 68.8% (EAS) and 80.5% (bilateral CI). A group of 22 listeners with normal hearing served as controls to compare and evaluate potential gap listening effects in implanted patients. Average speech reception thresholds in the EAS group were significantly lower than those for the bilateral CI group in all test conditions (CCITT 6.1 dB, p = 0.001; Fastl-noise 5.4 dB, p < 0.01; Oldenburg-(OL)-noise 1.6 dB, p < 0.05). Bilateral CI and EAS user groups showed a significant improvement of 4.3 dB (p = 0.004) and 5.4 dB (p = 0.002) between S0N0 and MSNF sound field conditions respectively, which signifies advantages caused by bilateral interaction in both groups. Performance in the control group showed a significant gap listening effect with a difference of 6.5 dB between modulated and unmodulated noise in S0N0, and a difference of 3.0 dB in MSNF. The ability to "glimpse" into short temporal masker gaps was absent in both groups of implanted subjects. Combined EAS in one ear supported by a hearing aid on the contralateral ear provided significantly improved speech perception compared with bilateral cochlear implantation. Although the scores for monosyllable words in quiet were higher in the bilateral CI group, the EAS group performed better in different noise and sound field conditions. Furthermore, the results indicated that binaural interaction between EAS in one ear and residual acoustic hearing in the opposite ear enhances speech perception in complex noise situations. Both bilateral CI and bimodal EAS users did not benefit from short temporal masker gaps, therefore the better performance of the EAS group in modulated noise conditions could be explained by the improved transmission of fundamental frequency cues in the lower-frequency region of acoustic hearing, which might foster the grouping of auditory objects.

Reaching for Sound Measures

A novel reaching for sound (RFS) methodology can yield a high level of spatial hearing ability in 2- to 3-year-old children with normal hearing and with bilateral cochlear implants (BiCIs). A growing number of children who are deaf are receiving BiCIs at a young age. Their spatial hearing abilities are emerging but highly variable within the population. Our novel reaching for sound method uses an ecologically valid approach that engages children and maintains their motivation. The present work was aimed at using the novel RFS method to evaluate spatial hearing in 2- to 3-year-olds with normal hearing and with BiCIs. Six children with BiCIs and 15 children with NH, ages 2 to 3 years participated. In the BiCI group, testing was performed in bilateral or single CI (unilateral) conditions. Loudspeakers were separated by ± 60, ± 45, ± 30, or ± 15 degrees. On each trial, a small toy was hidden behind one of the loudspeakers, and the child's task was to reach through a hole in the curtain above the loudspeaker, to indicate source location. Children were reinforced for correct responses. At each angle, the ability of the child to reach criterion of 80% or greater correct was assessed. All BiCI users reached criterion at all angles tested in the bilateral condition; however, performance was poorer when using a single CI. Of the 15 NH children, 13 were able to perform the task accurately and reached criterion at all angles. Spatial hearing skills studied with the RFS method revealed novel findings regarding the emergence of sound localization in very young BiCI users.

Sound Localization Skills in Children Who Use Bilateral Cochlear Implants and in Children With Normal Acoustic Hearing

To measure sound source localization in children who have sequential bilateral cochlear implants (BICIs); to determine whether localization accuracy correlates with performance on a right-left discrimination task (i.e., spatial acuity); to determine whether there is a measurable bilateral benefit on a sound source identification task (i.e., localization accuracy) by comparing performance under bilateral and unilateral listening conditions; and to determine whether sound source localization continues to improve with longer durations of bilateral experience. Two groups of children participated in this study: a group of 21 children who received BICIs in sequential procedures (5 to 14 years) and a group of 7 typically developing children with normal acoustic hearing (5 years). Testing was conducted in a large sound-treated booth with loudspeakers positioned on a horizontal arc with a radius of 1.2 m. Children participated in two experiments that assessed spatial hearing skills. Spatial hearing acuity was assessed with a discrimination task in which listeners determined whether a sound source was presented on the right or left side of center; the smallest angle at which performance on this task was reliably above chance is the minimum audible angle. Sound localization accuracy was assessed with a sound source identification task in which children identified the perceived position of the sound source from a multiloudspeaker array (7 or 15); errors are quantified using the root mean square (RMS) error. Sound localization accuracy was highly variable among the children with BICIs, with RMS errors ranging from 19 to 56 degrees . Performance of the normal hearing group, with RMS errors ranging from 9 to 29 degrees was significantly better. Within the BICI group, in 11 of 21 children, RMS errors were smaller in the bilateral versus unilateral listening condition, indicating bilateral benefit. There was a significant correlation between spatial acuity and sound localization accuracy (R = 0.68, p < 0.01), suggesting that children who achieve small RMS errors tend to have the smallest minimum audible angles. Although there was large intersubject variability, testing of 11 children in the BICI group at two sequential visits revealed a subset of children who show improvement in spatial hearing skills over time. A subset of children who use sequential BICIs can acquire sound localization abilities, even after long intervals between activation of hearing in the first- and second-implanted ears. This suggests that children with activation of the second implant later in life may be capable of developing spatial hearing abilities. The large variability in performance among the children with BICIs suggests that maturation of sound localization abilities in children with BICIs may be dependent on various individual subject factors such as age of implantation and chronological age.