Bilateral cochlear implants in children: Effects of auditory experience and deprivation on auditory perception

Two are better than one: Differences in cortical EEG patterns during auditory and visual verbal working memory processing between Unilateral and Bilateral Cochlear Implanted children

Despite the proven effectiveness of cochlear implant (CI) in the hearing restoration of deaf or hard-of-hearing (DHH) children, to date, extreme variability in verbal working memory (VWM) abilities is observed in both unilateral and bilateral CI user children (CIs). Although clinical experience has long observed deficits in this fundamental executive function in CIs, the cause to date is still unknown. Here, we have set out to investigate differences in brain functioning regarding the impact of monaural and binaural listening in CIs compared with normal hearing (NH) peers during a three-level difficulty n-back task undertaken in two sensory modalities (auditory and visual). The objective of this pioneering study was to identify electroencephalographic (EEG) marker pattern differences in visual and auditory VWM performances in CIs compared to NH peers and possible differences between unilateral cochlear implant (UCI) and bilateral cochlear implant (BCI) users. The main results revealed differences in theta and gamma EEG bands. Compared with hearing controls and BCIs, UCIs showed hypoactivation of theta in the frontal area during the most complex condition of the auditory task and a correlation of the same activation with VWM performance. Hypoactivation in theta was also observed, again for UCIs, in the left hemisphere when compared to BCIs and in the gamma band in UCIs compared to both BCIs and NHs. For the latter two, a correlation was found between left hemispheric gamma oscillation and performance in the audio task. These findings, discussed in the light of recent research, suggest that unilateral CI is deficient in supporting auditory VWM in DHH. At the same time, bilateral CI would allow the DHH child to approach the VWM benchmark for NH children. The present study suggests the possible effectiveness of EEG in supporting, through a targeted approach, the diagnosis and rehabilitation of VWM in DHH children.

Head and Eye Movements Reveal Compensatory Strategies for Acute Binaural Deficits During Sound Localization

The present study aimed to define use of head and eye movements during sound localization in children and adults to: (1) assess effects of stationary versus moving sound and (2) define effects of binaural cues degraded through acute monaural ear plugging. Thirty-three youth (MAge = 12.9 years) and seventeen adults (MAge = 24.6 years) with typical hearing were recruited and asked to localize white noise anywhere within a horizontal arc from -60° (left) to +60° (right) azimuth in two conditions (typical binaural and right ear plugged). In each trial, sound was presented at an initial stationary position (L1) and then while moving at ∼4°/s until reaching a second position (L2). Sound moved in five conditions (±40°, ±20°, or 0°). Participants adjusted a laser pointer to indicate L1 and L2 positions. Unrestricted head and eye movements were collected with gyroscopic sensors on the head and eye-tracking glasses, respectively. Results confirmed that accurate sound localization of both stationary and moving sound is disrupted by acute monaural ear plugging. Eye movements preceded head movements for sound localization in normal binaural listening and head movements were larger than eye movements during monaural plugging. Head movements favored the unplugged left ear when stationary sounds were presented in the right hemifield and during sound motion in both hemifields regardless of the movement direction. Disrupted binaural cues have greater effects on localization of moving than stationary sound. Head movements reveal preferential use of the better-hearing ear and relatively stable eye positions likely reflect normal vestibular-ocular reflexes.

Cochlear implants: the effects of age on outcomes

INTRODUCTION

Cochlear implants (CIs) provide access to sound for children and adults who do not receive adequate benefit from hearing aids. Age at implantation is known to affect outcomes across the lifespan.

AREAS COVERED

The effects of age on CI outcomes are examined for infants, children, adolescents, and older adults. A variety of outcome measures are considered, including speech perception, language, cognition, and quality of life measures.

EXPERT OPINION/COMMENTARY

For those meeting candidacy criteria, CIs are beneficial at any age. In general, younger age is related to greater benefit when considering pre-lingual deafness. Other factors such as additional disabilities, may mitigate this effect. Post-lingually deafened adults demonstrate similar benefit regardless of age, though the oldest individuals (80+) may see smaller degrees of improvement from preoperative scores. Benefit can be measured in many ways, and the areas of greatest benefit may vary based on age: young children appear to see the greatest effects of age at implantation on language measures, whereas scores on cognitive measures appear to be most impacted for the oldest population. Future research should consider implantation at extreme ages (5-9 months or > 90 years), unconventional measures of CI benefit including qualitative assessments, and longitudinal designs.

Interaural time difference sensitivity under binaural cochlear implant stimulation persists at high pulse rates up to 900 pps

Spatial hearing remains one of the major challenges for bilateral cochlear implant (biCI) users, and early deaf patients in particular are often completely insensitive to interaural time differences (ITDs) delivered through biCIs. One popular hypothesis is that this may be due to a lack of early binaural experience. However, we have recently shown that neonatally deafened rats fitted with biCIs in adulthood quickly learn to discriminate ITDs as well as their normal hearing litter mates, and perform an order of magnitude better than human biCI users. Our unique behaving biCI rat model allows us to investigate other possible limiting factors of prosthetic binaural hearing, such as the effect of stimulus pulse rate and envelope shape. Previous work has indicated that ITD sensitivity may decline substantially at the high pulse rates often used in clinical practice. We therefore measured behavioral ITD thresholds in neonatally deafened, adult implanted biCI rats to pulse trains of 50, 300, 900 and 1800 pulses per second (pps), with either rectangular or Hanning window envelopes. Our rats exhibited very high sensitivity to ITDs at pulse rates up to 900 pps for both envelope shapes, similar to those in common clinical use. However, ITD sensitivity declined to near zero at 1800 pps, for both Hanning and rectangular windowed pulse trains. Current clinical cochlear implant (CI) processors are often set to pulse rates ≥ 900 pps, but ITD sensitivity in human CI listeners has been reported to decline sharply above ~ 300 pps. Our results suggest that the relatively poor ITD sensitivity seen at > 300 pps in human CI users may not reflect the hard upper limit of biCI ITD performance in the mammalian auditory pathway. Perhaps with training or better CI strategies good binaural hearing may be achievable at pulse rates high enough to allow good sampling of speech envelopes while delivering usable ITDs.

Hearing Preservation and Spatial Hearing Outcomes After Cochlear Implantation in Children With TMPRSS3 Mutations

OBJECTIVE

Investigate hearing preservation and spatial hearing outcomes in children with TMPRSS3 mutations who received bilateral cochlear implantation.

STUDY DESIGN AND METHODS

Longitudinal case series report. Two siblings (ages, 7 and 4 yr) with TMPRSS3 mutations with down-sloping audiograms received sequential bilateral cochlear implantation with hearing preservation with low-frequency acoustic amplification and high-frequency electrical stimulation. Spatial hearing, including speech perception and localization, was assessed at three time points: preoperative, postoperative of first and second cochlear implant (CI).

RESULTS

Both children showed low-frequency hearing preservation in unaided, acoustic-only audiograms. Both children demonstrated improvements in speech perception in both quiet and noise after CI activations. The emergence of spatial hearing was observed. Each child's overall speech perception and spatial hearing when listening with bilateral CIs were within the range or better than published group data from children with bilateral CIs of other etiology.

CONCLUSION

Bilateral cochlear implantation with hearing preservation is a viable option for managing hearing loss for pediatric patients with TMPRSS3 mutations.

Longitudinal Effects of Simultaneous and Sequential Bilateral Cochlear Implantation on Cortical Auditory-Evoked Potentials Recorded at Cz in a Large Cohort of Children

OBJECTIVES

Auditory development after bilateral cochlear implantation in children has been measured using source localization of multi-channel late latency responses. It is not clear, however, whether this development can be tracked using a more clinically feasible method of recording from one active recording electrode placed at mid-line center of the head (Cz).

DESIGN

In this prospective cohort study, cortical auditory-evoked potential responses (CAEPs) were recorded from Cz referenced to each earlobe (Cz-CAEP) from 222 children with bilateral cochlear implant (CI); 128 (mean ± SD age: 2.78 ± 3.30 years) received both CIs in the same surgery (simultaneous group) and 94 (aged 7.72 ± 4.45 years) received a second CI after 4.21 ± 2.98 years of unilateral CI use. We sought to (1) identify cortical development over the first couple of years of bilateral CI use; (2) measure known asymmetries in auditory development between the CIs; and (3) detect the effects of bilateral rather than unilateral CI use. 4556 Cz-CAEPs were recorded across the cohort over 33.50 ± 7.67 months duration of bilateral CI use. Given concerns related to peak picking, amplitude areas were measured across two response time windows (50 to 199 ms and 200 to 400 ms).

RESULTS

Results indicated that small response amplitudes occur at initial CI use and amplitudes increase in the negative or positive direction rapidly over the first months of CI use in both time windows. Asymmetries between Cz-CAEPs evoked by each CI were found in the sequential group and reduced with bilateral CI use, particularly in the first time window; these differences increased with longer inter-implant delay. Bilaterally evoked Cz-CAEPs were larger in amplitude than unilateral responses from either CI in the simultaneous group. In the sequential group, bilateral responses were similar to responses from the first implanted side but increased in relative amplitude with bilateral CI use. The Cz-CAEP measures were not able to predict asymmetries or bilateral benefits in speech perception measures.

CONCLUSIONS

The Cz-CAEP was able to indicate cortical detection of CI input and showed gross morphological changes with bilateral CI use. Findings indicate Cz-CAEPs can be used to identify gross changes in auditory development in children with bilateral CIs, but they are less sensitive to tracking the remaining abnormalities that are measured by multi-channel CAEPs and speech perception testing.

Effects of Abacus Training on Auditory Spatial Maturation in Children with Normal Hearing

Introduction  The spatial auditory system, though developed at birth, attains functional maturity in the late childhood (12 years). Spatial changes during childhood affect navigation in the environment and source segregation. Accommodation of a new skill through learning, especially during childhood, can expedite this process. Objective  To explore the auditory spatial benefits of abacus training on psychoacoustic metrics in children. The study also aimed to identify the most sensitive metric to abacus training related changes in spatial processing, and utilize this metric for a detailed spatial error profiling. Methods  A standard group comparison analysis with 90 participants divided into three groups: I: children with abacus training (C-AT); II: children with no training (C-UT); III: adults with no training (A-UT). The groups underwent a series of psychoacoustic tests, such as interaural time difference (ITD), interaural level difference (ILD), and virtual auditory space identification (VASI), as well as perceptual tests such as the Kannada version of the speech, spatial, and quality questionnaire (K-SSQ). Results  Significant group differences were observed in the multivariate analysis of variance (MANOVA) and post-hoc tests, with the C-AT group showing significantly lower ILD scores ( p  = 0.01) and significantly higher VASI scores ( p <0.001) compared to the C-UT group, which is indicative of better spatial processing abilities in the former group. The discriminant function (DF) analyses showed that the VASI was the most sensitive metric for training-related changes, based on which elaborate error analyses were performed. Conclusions  Despite the physiological limits of the immature neural framework, the performance of the C-AT group was equivalent to that of untrained adults on psychoacoustic tests, which is reflective of the positive role of abacus training in expediting auditory spatial maturation.

Effects of the intensified frequency and time ranges on consonant enhancement in bilateral cochlear implant and hearing aid users

A previous study demonstrated that consonant recognition improved significantly in normal hearing listeners when useful frequency and time ranges were intensified by 6 dB. The goal of this study was to determine whether bilateral cochlear implant (BCI) and bilateral hearing aid (BHA) users experienced similar enhancement on consonant recognition with these intensified spectral and temporal cues in noise. In total, 10 BCI and 10 BHA users participated in a recognition test using 14 consonants. For each consonant, we used the frequency and time ranges that are critical for its recognition (called “target frequency and time range”), identified from normal hearing listeners. Then, a signal processing tool called the articulation-index gram (AI-Gram) was utilized to add a 6 dB gain to target frequency and time ranges. Consonant recognition was monaurally and binaurally measured under two signal processing conditions, unprocessed and intensified target frequency and time ranges at +5 and +10 dB signal-to-noise ratio and in quiet conditions. We focused on three comparisons between the BCI and BHA groups: (1) AI-Gram benefits (i.e., before and after intensifying target ranges by 6 dB), (2) enhancement in binaural benefits (better performance with bilateral devices compared to the better ear alone) via the AI-Gram processing, and (3) reduction in binaural interferences (poorer performance with bilateral devices compared to the better ear alone) via the AI-Gram processing. The results showed that the mean AI-Gram benefit was significantly improved for the BCI (max 5.9%) and BHA (max 5.2%) groups. However, the mean binaural benefit was not improved after AI-Gram processing. Individual data showed wide ranges of the AI-Gram benefit (max −1 to 23%) and binaural benefit (max −7.6 to 13%) for both groups. Individual data also showed a decrease in binaural interference in both groups after AI-Gram processing. These results suggest that the frequency and time ranges, intensified by the AI-Gram processing, contribute to consonant enhancement for monaural and binaural listening and both BCI and BHA technologies. The intensified frequency and time ranges helped to reduce binaural interference but contributed less to the synergistic binaural benefit in consonant recognition for both groups.

Cochlear Implantation in Young Mandarin-Speaking Children: One Year After First Fitting

INTRODUCTION

Bilateral cochlear implantation has been shown to be beneficial in terms of sound localization and speech recognition in children with congenital deafness. However, little is known about the benefits of bilateral cochlear implantationin children who communicate in a tonal language such as Mandarin. This study aims to investigate the auditory perception and speech intelligibility of Mandarin-speaking children 1 year after first fitting.

MATERIALS AND METHODS

Twenty-nine children aged between 11.5 and 17.9 months with severe-to-profound bilateral sensorineural hearing loss were recruited; 10 were unilaterally implanted and 19 were bilaterally implanted. A test battery was used to monitor improvements during the first year of cochlear implant use.

RESULTS

Bilaterally implanted children scored better in the spatial domain of the Speech, Spatial and Qualities of hearing scale for Parents (SSQ-P) in comparison to unilaterally implanted children. Significant improvements were observed in auditory performance and speech intelligibility at 6 and 12 months after first fitting for both groups of children.

DISCUSSION

Young children that speak a tonal language, such as Mandarin, can obtain significant improvements in hearing and speech abilities within the first year of cochlear implant use. Furthermore, bilateral implantation provides users with better spatial hearing in comparison to unilateral implantation.

Analysis of Health Disparities in the Screening and Diagnosis of Hearing Loss: Early Hearing Detection and Intervention Hearing Screening Follow-Up Survey

PURPOSE

The purpose of this study was to (a) provide introductory literature regarding cultural constructs, health disparities, and social determinants of health (SDoH); (b) summarize the literature regarding the Centers for Disease Control and Prevention (CDC) Early Hearing Detection and Intervention (EHDI) Hearing Screening Follow-Up Survey (HSFS) data; (c) explore the CDC EHDI HSFS data regarding the contribution of maternal demographics to loss-to-follow-up/loss-to-documentation (LTF/D) between hearing screening and audiologic diagnosis for 2016, 2017, and 2018; and (d) examine these health disparities within the context of potential ethnoracial biases.

METHOD

This is a comprehensive narrative literature review of cultural constructs, hearing health disparities, and SDoH as they relate to the CDC EHDI HSFS data. We explore the maternal demographic data reported on the CDC EHDI website and report disparities for maternal age, education, ethnicity, and race for 2016, 2017, and 2018. We focus on LTF/D for screening and diagnosis within the context of racial and cultural bias.

RESULTS

A literature review demonstrates the increase in quality of the CDC EHDI HSFS data over the past 2 decades. LTF/D rates for hearing screening and audiologic diagnostic testing have improved from higher than 60% to current rates of less than 30%. Comparisons of diagnostic completion rates reported on the CDC website for the EHDI HSFS 2016, 2017, and 2018 data show trends for maternal age, education, and race, but not for ethnicity. Trends were defined as changes more than 10% for variables averaged over a 3-year period (2016-2018).

CONCLUSIONS

Although there have been significant improvements in LTF/D over the past 2 decades, there continue to be opportunities for further improvement. Beyond neonatal screening, delays continue to be reported in the diagnosis of young children with hearing loss. Notwithstanding the extraordinarily diverse families within the United States, the imperative is to minimize such delays so that all children with hearing loss can, at the very least, have auditory accessibility to spoken language by 3 months of age. Conscious awareness is essential before developing a potentially effective plan of action that might remediate the problem.

Cortical imbalance following delayed restoration of bilateral hearing in deaf adolescents

Unilateral auditory deprivation in early childhood can lead to cortical strengthening of inputs from the stimulated side, yet the impact of this on bilateral processing when inputs are later restored beyond an early sensitive period is unknown. To address this, we conducted a longitudinal study with 13 bilaterally profoundly deaf adolescents who received unilateral access to sound via a cochlear implant (CI) in their right ear in early childhood before receiving bilateral access to sound a decade later via a second CI in their left ear. Auditory‐evoked cortical responses to unilateral and bilateral stimulation were measured repeatedly using electroencephalogram from 1 week to 14 months after activation of their second CI. Early cortical responses from the newly implanted ear and bilateral stimulation were atypically lateralized to the left ipsilateral auditory cortex. Duration of unilateral deafness predicted an unexpectedly stronger representation of inputs from the newly implanted, compared to the first implanted ear, in left auditory cortex. Significant initial reductions in responses were observed, yet a left‐hemisphere bias and unequal weighting of inputs favoring the long‐term deaf ear did not converge to a balanced state observed in the binaurally developed system. Bilateral response enhancement was significantly reduced in left auditory cortex suggesting deficits in ipsilateral response inhibition of new, dominant, inputs during bilateral processing. These findings paradoxically demonstrate the adaptive capacity of the adolescent auditory system beyond an early sensitive period for bilateral input, as well as restrictions on its potential to fully reverse cortical imbalances driven by long‐term unilateral deafness.

Usher syndrome IIIA: a review of the disorder and preclinical research advances in therapeutic approaches

Usher syndrome (USH) is an autosomal recessive disorder characterized by sensorineural hearing loss, progressive pigmentary retinopathy, and vestibular dysfunction. The degree and onset of hearing loss vary among subtypes I, II, and III, while blindness often occurs in the second to fourth decades of life. Usher type III (USH3), characterized by postlingual progressive sensorineural hearing loss, varying levels of vestibular dysfunction, and varying degrees of visual impairment, typically manifests in the first to second decades of life. While USH3 is rare, it is highly prevalent in certain populations. RP61, USH3, and USH3A symbolize the same disorder, with the latter symbol used more frequently in recent literature. This review focuses on the clinical features, epidemiology, molecular genetics, treatment, and research advances for sensory deficits in USH3A.

Attention to Speech and Music in Young Children with Bilateral Cochlear Implants: A Pupillometry Study

Early bilateral cochlear implants (CIs) may enhance attention to speech, and reduce cognitive load in noisy environments. However, it is sometimes difficult to measure speech perception and listening effort, especially in very young children. Behavioral measures cannot always be obtained in young/uncooperative children, whereas objective measures are either difficult to assess or do not reliably correlate with behavioral measures. Recent studies have thus explored pupillometry as a possible objective measure. Here, pupillometry is introduced to assess attention to speech and music in noise in very young children with bilateral CIs (N = 14, age: 17–47 months), and in the age-matched group of normally-hearing (NH) children (N = 14, age: 22–48 months). The results show that the response to speech was affected by the presence of background noise only in children with CIs, but not NH children. Conversely, the presence of background noise altered pupil response to music only in in NH children. We conclude that whereas speech and music may receive comparable attention in comparable listening conditions, in young children with CIs, controlling for background noise affects attention to speech and speech processing more than in NH children. Potential implementations of the results for rehabilitation procedures are discussed.

American Cochlear Implant Alliance Task Force Guidelines for Determining Cochlear Implant Candidacy in Children

This article summarizes the available evidence on pediatric cochlear implantation to provide current guidelines for clinical protocols and candidacy recommendations in the United States. Candidacy determination involves specification of audiologic and medical criteria per guidelines of the Food and Drug Administration. However, recommendations for a cochlear implant evaluation also should maintain flexibility and consider a child’s skill progression (i.e., month-for-month progress in speech, language, and auditory development) and quality of life with appropriately fit hearing aids. Moreover, evidence supports medical and clinical decisions based on other factors, including (a) ear-specific performance, which affords inclusion of children with asymmetric hearing loss and single-sided deafness as implant candidates; (b) ear-specific residual hearing, which influences surgical technique and device selection to optimize hearing; and (c) early intervention to minimize negative long-term effects on communication and quality of life related to delayed identification of implant candidacy, later age at implantation, and/or limited commitment to an audiologic rehabilitation program. These evidence-based guidelines for current clinical protocols in determining pediatric cochlear implant candidacy encourage a team-based approach focused on the whole child and the family system.

Sound source localization patterns and bilateral cochlear implants: Age at onset of deafness effects

The ability to determine a sound’s location is critical in everyday life. However, sound source localization is severely compromised for patients with hearing loss who receive bilateral cochlear implants (BiCIs). Several patient factors relate to poorer performance in listeners with BiCIs, associated with auditory deprivation, experience, and age. Critically, characteristic errors are made by patients with BiCIs (e.g., medial responses at lateral target locations), and the relationship between patient factors and the type of errors made by patients has seldom been investigated across individuals. In the present study, several different types of analysis were used to understand localization errors and their relationship with patient-dependent factors (selected based on their robustness of prediction). Binaural hearing experience is required for developing accurate localization skills, auditory deprivation is associated with degradation of the auditory periphery, and aging leads to poorer temporal resolution. Therefore, it was hypothesized that earlier onsets of deafness would be associated with poorer localization acuity and longer periods without BiCI stimulation or older age would lead to greater amounts of variability in localization responses. A novel machine learning approach was introduced to characterize the types of errors made by listeners with BiCIs, making them simple to interpret and generalizable to everyday experience. Sound localization performance was measured in 48 listeners with BiCIs using pink noise trains presented in free-field. Our results suggest that older age at testing and earlier onset of deafness are associated with greater average error, particularly for sound sources near the center of the head, consistent with previous research. The machine learning analysis revealed that variability of localization responses tended to be greater for individuals with earlier compared to later onsets of deafness. These results suggest that early bilateral hearing is essential for best sound source localization outcomes in listeners with BiCIs.

Novel Approaches to Measure Spatial Release From Masking in Children With Bilateral Cochlear Implants

OBJECTIVES

To investigate the role of auditory cues for spatial release from masking (SRM) in children with bilateral cochlear implants (BiCIs) and compare their performance with children with normal hearing (NH). To quantify the contribution to speech intelligibility benefits from individual auditory cues: head shadow, binaural redundancy, and interaural differences; as well as from multiple cues: SRM and binaural squelch. To assess SRM using a novel approach of adaptive target-masker angular separation, which provides a more functionally relevant assessment in realistic complex auditory environments.

DESIGN

Children fitted with BiCIs (N = 11) and with NH (N = 18) were tested in virtual acoustic space that was simulated using head-related transfer functions measured from individual children with BiCIs behind the ear and from a standard head and torso simulator for all NH children. In experiment I, by comparing speech reception thresholds across 4 test conditions that varied in target-masker spatial separation (colocated versus separated at 180°) and listening conditions (monaural versus binaural/bilateral listening), intelligibility benefits were derived for individual auditory cues for SRM. In experiment II, SRM was quantified using a novel measure to find the minimum angular separation (MAS) between the target and masker to achieve a fixed 20% intelligibility improvement. Target speech was fixed at either +90 or -90° azimuth on the side closer to the better ear (+90° for all NH children) and masker locations were adaptively varied.

RESULTS

In experiment I, children with BiCIs as a group had smaller intelligibility benefits from head shadow than NH children. No group difference was observed in benefits from binaural redundancy or interaural difference cues. In both groups of children, individuals who gained a larger benefit from interaural differences relied less on monaural head shadow, and vice versa. In experiment II, all children with BiCIs demonstrated measurable MAS thresholds <180° and on average larger than that from NH children. Eight of 11 children with BiCIs and all NH children had a MAS threshold <90°, requiring interaural differences only to gain the target intelligibility benefit; whereas the other 3 children with BiCIs had a MAS between 120° and 137°, requiring monaural head shadow for SRM.

CONCLUSIONS

When target and maskers were separated at 180° on opposing hemifields, children with BiCIs demonstrated greater intelligibility benefits from head shadow and interaural differences than previous literature showed with a smaller separation. Children with BiCIs demonstrated individual differences in using auditory cues for SRM. From the MAS thresholds, more than half of the children with BiCIs demonstrated robust access to interaural differences without needing additional monaural head shadow for SRM. Both experiments led to the conclusion that individualized fitting strategies in the bilateral devices may be warranted to maximize spatial hearing for children with BiCIs in complex auditory environments.

Interdisciplinary Approaches to the Study of Listening Effort in Young Children with Cochlear Implants

Very early bilateral implantation is thought to significantly reduce the attentional effort required to acquire spoken language, and consequently offer a profound improvement in quality of life. Despite the early intervention, however, auditory and communicative outcomes in children with cochlear implants remain poorer than in hearing children. The distorted auditory input via the cochlear implants requires more auditory attention resulting in increased listening effort and fatigue. Listening effort and fatigue may critically affect attention to speech, and in turn language processing, which may help to explain the variation in language and communication abilities. However, measuring attention to speech and listening effort is demanding in infants and very young children. Three objective techniques for measuring listening effort are presented in this paper that may address the challenges of testing very young and/or uncooperative children with cochlear implants: pupillometry, electroencephalography, and functional near-infrared spectroscopy. We review the studies of listening effort that used these techniques in paediatric populations with hearing loss, and discuss potential benefits of the systematic evaluation of listening effort in these populations.

The Importance of Access to Bilateral Hearing through Cochlear Implants in Children

Children with hearing loss require early access to sound in both ears to support their development. In this article, we describe barriers to providing bilateral hearing and developmental consequences of delays during early sensitive periods. Barriers include late identification of hearing loss in one or both ears and delayed access to intervention with hearing devices such as cochlear implants. Effects of delayed bilateral input on the auditory pathways and brain are discussed as well as behavioral effects on speech perception and other developmental outcomes including language and academics. Evidence for these effects has supported an evolution in cochlear implant candidacy in children that was started with unilateral implantation in children with profound deafness bilaterally to bilateral implantation to implantation of children with asymmetric hearing loss including children with single-side deafness. Opportunities to enhance the developmental benefits of bilateral hearing in children with hearing loss are also discussed including efforts to improve binaural/spatial hearing and consideration of concurrent vestibular deficits which are common in children with hearing loss.

Cochlear Implants in Single-Sided Deafness. Comparison Between Children and Adult Populations With Post-lingually Acquired Severe to Profound Hearing Loss

Objective: To determine audiological and clinical results of cochlear implantation (CI) comparing two populations with single-sided deafness (SSD): post-lingually deaf children between 6 and 12 years of age, and post-lingually deaf adults, in order to evaluate the effect of CI in different age groups. Design: Retrospective case review. Setting: Tertiary clinic. Patients and Method: Twenty-three children and twenty-one adult patients that were candidates for CI with single-side deafness were included. In all cases we evaluate: Speech perception thresholds; disyllabic words test (65 dB SPL) were performed in the modalities S0-SCI-SNH and Auditory Lateralization Test. The Speech, Spatial, and Qualities of Hearing Scale (SSQ) questionnaire was also used. All results were obtained after 12 months of CI activation. Results: In children, the most common etiology was idiopathic sensory-neural hearing loss. They showed positive results in the Auditory Lateralization Test. In the Speech Test, word recognition in noise improved from 2% preoperatively to 61.1% at a mean follow-up of 1 year (S0 condition) in children [test with signal in CI side 60% and signal normal hearing side (plugged) 31%]. The processor was used for >12 h in all cases. With respect to the SSQ questionnaire, parents were more satisfied within the postoperative period than within the preoperative period. For adults, the most common etiology was idiopathic sudden sensorineural hearing loss (SNHL). Positive results in the Auditory Lateralization Test were found. With respect to the Speech Test in quiet conditions: Word recognition in noise improved from 5.7% preoperatively to 71.8% at a mean follow-up of 1 year [test with signal in CI side 68% and signal normal hearing side (plugged) 41%]. The processor was used for >12 h. In the SSQ questionnaire, the post-operative results showed a beneficial effect of the CI. No adverse events were reported during the study period. No differences were found between children and adults in all tests in this study. Conclusions: Cochlear implantation in post-lingually deaf adults and children with SSD can achieve a speech perception outcome comparable with CI in conventional candidates. Improvements in spatial hearing were also observed. Careful patient selection and counseling regarding potential benefits are important to optimize outcomes.

Functional Consequences of Poor Binaural Hearing in Development: Evidence From Children With Unilateral Hearing Loss and Children Receiving Bilateral Cochlear Implants

Poor binaural hearing in children was hypothesized to contribute to related cognitive and academic deficits. Children with unilateral hearing have normal hearing in one ear but no access to binaural cues. Their cognitive and academic deficits could be unique from children receiving bilateral cochlear implants (CIs) at young ages who have poor access to spectral cues and impaired binaural sensitivity. Both groups are at risk for vestibular/balance deficits which could further contribute to memory and learning challenges. Eighty-eight children (43 male:45 female, aged 9.89  ±  3.40 years), grouped by unilateral hearing loss (n = 20), bilateral CI (n = 32), and typically developing (n = 36), completed a battery of sensory, cognitive, and academic tests. Analyses revealed that children in both hearing loss groups had significantly poorer skills (accounting for age) on most tests than their normal hearing peers. Children with unilateral hearing loss had more asymmetric speech perception than children with bilateral CIs (p < .0001) but balance and language deficits (p = .0004, p < .0001, respectively) were similar in the two hearing loss groups (p > .05). Visuospatial memory deficits occurred in both hearing loss groups (p = .02) but more consistently across tests in children with unilateral hearing loss. Verbal memory was not significantly different than normal (p > .05). Principal component analyses revealed deficits in a main cluster of visuospatial memory, oral language, mathematics, and reading measures (explaining 46.8% data variability). The remaining components revealed clusters of self-reported hearing, balance and vestibular function, and speech perception deficits. The findings indicate significant developmental impacts of poor binaural hearing in children.

Development of binaural temporal fine structure sensitivity in children

The highest frequency for which the temporal fine structure (TFS) of a sinewave can be compared across ears varies between listeners with an upper limit of about 1400 Hz for young normal-hearing adults (YNHA). In this study, binaural TFS sensitivity was investigated for 63 typically developing children, aged 5 years, 6 months to 9 years, 4 months using the temporal fine structure-adaptive frequency (TFS-AF) test of Füllgrabe, Harland, Sęk, and Moore [Int. J. Audiol. 56, 926-935 (2017)]. The test assesses the highest frequency at which an interaural phase difference (IPD) of ϕ° can be distinguished from an IPD of 0°. The values of ϕ were 30° and 180°. The starting frequency was 200 Hz. The thresholds for the children were significantly lower (worse) than the thresholds reported by Füllgrabe, Harland, Sęk, and Moore [Int. J. Audiol. 56, 926-935 (2017)] for YNHA. For both values of ϕ, the median age at which children performed above chance level was significantly higher (p < 0.001) than for those who performed at chance. For the subgroup of 40 children who performed above chance for ϕ = 180°, the linear regression analyses showed that the thresholds for ϕ = 180° increased (improved) significantly with increasing age (p < 0.001) with adult-like thresholds predicted to be reached at 10 years, 2 months of age. The implications for spatial release from masking are discussed.

Speech-in-Noise Recognition With More Realistic Implementations of a Binaural Cochlear-Implant Sound Coding Strategy Inspired by the Medial Olivocochlear Reflex

OBJECTIVES

Cochlear implant (CI) users continue to struggle understanding speech in noisy environments with current clinical devices. We have previously shown that this outcome can be improved by using binaural sound processors inspired by the medial olivocochlear (MOC) reflex, which involve dynamic (contralaterally controlled) rather than fixed compressive acoustic-to-electric maps. The present study aimed at investigating the potential additional benefits of using more realistic implementations of MOC processing.

DESIGN

Eight users of bilateral CIs and two users of unilateral CIs participated in the study. Speech reception thresholds (SRTs) for sentences in competition with steady state noise were measured in unilateral and bilateral listening modes. Stimuli were processed through two independently functioning sound processors (one per ear) with fixed compression, the current clinical standard (STD); the originally proposed MOC strategy with fast contralateral control of compression (MOC1); a MOC strategy with slower control of compression (MOC2); and a slower MOC strategy with comparatively greater contralateral inhibition in the lower-frequency than in the higher-frequency channels (MOC3). Performance with the four strategies was compared for multiple simulated spatial configurations of the speech and noise sources. Based on a previously published technical evaluation of these strategies, we hypothesized that SRTs would be overall better (lower) with the MOC3 strategy than with any of the other tested strategies. In addition, we hypothesized that the MOC3 strategy would be advantageous over the STD strategy in listening conditions and spatial configurations where the MOC1 strategy was not.

RESULTS

In unilateral listening and when the implant ear had the worse acoustic signal-to-noise ratio, the mean SRT was 4 dB worse for the MOC1 than for the STD strategy (as expected), but it became equal or better for the MOC2 or MOC3 strategies than for the STD strategy. In bilateral listening, mean SRTs were 1.6 dB better for the MOC3 strategy than for the STD strategy across all spatial configurations tested, including a condition with speech and noise sources colocated at front where the MOC1 strategy was slightly disadvantageous relative to the STD strategy. All strategies produced significantly better SRTs for spatially separated than for colocated speech and noise sources. A statistically significant binaural advantage (i.e., better mean SRTs across spatial configurations and participants in bilateral than in unilateral listening) was found for the MOC2 and MOC3 strategies but not for the STD or MOC1 strategies.

CONCLUSIONS

Overall, performance was best with the MOC3 strategy, which maintained the benefits of the originally proposed MOC1 strategy over the STD strategy for spatially separated speech and noise sources and extended those benefits to additional spatial configurations. In addition, the MOC3 strategy provided a significant binaural advantage, which did not occur with the STD or the original MOC1 strategies.

Bilateral Cochlear Implantation in Children: Long-Term Outcome in the Adult Population With Special Emphasis on the Bilateral Benefit

OBJECTIVE

To investigate the benefit of bilateral cochlear implantation in adults, who had been implanted being a child under the age of 10 years.

STUDY DESIGN

Retrospective data analysis.

SETTING

Tertiary referral center with a large cochlear implant program.

MAIN OUTCOME MEASURES

Speech understanding in the Freiburg monosyllabic words in quiet and the HSM sentence test in quiet and in background noise.

PATIENTS

Seventy-seven bilaterally cochlear implantation implanted adults.

RESULTS

Bilateral cochlear implantation in children under the age of 10 years results in a significant benefit in speech comprehension in adulthood. In addition, a dependency regarding the time between the implantations and speech intelligibility was found.

CONCLUSION

The results emphasize the benefit of bilateral cochlear implantation with a short interval between the operations in young children not only during formative years but also in adulthood.

Dichotic listening performance with cochlear-implant simulations of ear asymmetry is consistent with difficulty ignoring clearer speech

There are an increasing number of bilateral and single-sided-deafness cochlear-implant (CI) users who hope to achieve improved spatial-hearing abilities through access to sound in both ears. It is, however, unclear how speech is processed when inputs are functionally asymmetrical, which may have an impact on spatial-hearing abilities. Therefore, functionally asymmetrical hearing was controlled and parametrically manipulated using a channel vocoder as a CI simulation. In Experiment 1, normal-hearing (NH) listeners performed a dichotic listening task (i.e., selective attention to one ear, ignoring the other) using asymmetrical signal degradation. Spectral resolution varied independently in each ear (4, 8, 16 channels, and unprocessed control). Performance decreased with decreasing resolution in the target ear and increasing resolution in the interferer ear. In Experiment 2, these results were replicated using a divided attention task (attend to both ears, report one after sentence completion) in both NH and bilateral CI listeners, although overall performance was lower than in Experiment 1. In Experiment 3, frequency-to-place mismatch simulated shallow CI insertion depths (0, 3, 6-mm shifts, and unprocessed control). Performance mostly decreased with increasing shift in the target ear and decreasing shift in the interferer ear; however, performance nonmonotonicities occurred. The worst performance occurred when the shift matched across ears, suggesting that pitch similarity increases difficulty. The results show that it is more difficult to attend an ear that is relatively degraded or distorted, which may set spatial-hearing limitations for CI users when trying to attend to a target in complex auditory scenes.

Spatial Release From Masking in Bimodal and Bilateral Pediatric Cochlear Implant Recipients

Purpose Traditional clinical measures of cochlear implant (CI) recipient performance may not fully evaluate the benefit of bimodal listening (hearing aid contralateral to a CI). The clinical assessment of spatial release from masking (SRM) may be a sensitive measure of the benefit of listening with bimodal stimulation. This study compared the SRM of pediatric bimodal and bilateral CI listeners using a clinically feasible method, and investigated variables that may contribute to speech recognition performance with spatially separated maskers. Method Forty pediatric bimodal (N = 20) and bilateral CI (N = 20) participants were assessed in their best aided listening condition on sentence recognition in a four-talker masker. Testing was completed with target and masker colocated at 0° azimuth, and with the masker directed at 90° to either ear. SRM was calculated as the difference in performance between the colocated and each 90° condition. A two-way mixed-methods analysis of variance was used to compare performance between groups in the three masker conditions. Multiple regression analyses were conducted to investigate potential predictors for SRM asymmetry including hearing history, unaided thresholds, word recognition, duration of device use, and acoustic bandwidth. Results Both groups demonstrated SRM, with significantly better recognition in each 90° condition as compared to the colocated condition. The groups did not differ significantly in SRM. The multiple regression analyses did not reveal any significant predictors of SRM asymmetry. Conclusions Bimodal and bilateral CI listeners demonstrated similar amounts of SRM. While no specific variables predicted SRM asymmetry in bimodal listeners, pediatric bimodal and bilateral CI recipients should expect similar amounts of SRM regardless of the side of the masker. SRM asymmetry in pediatric bimodal listeners may signal a need for consideration of a second CI.

Microsecond interaural time difference discrimination restored by cochlear implants after neonatal deafness

Spatial hearing in cochlear implant (CI) patients remains a major challenge, with many early deaf users reported to have no measurable sensitivity to interaural time differences (ITDs). Deprivation of binaural experience during an early critical period is often hypothesized to be the cause of this shortcoming. However, we show that neonatally deafened (ND) rats provided with precisely synchronized CI stimulation in adulthood can be trained to lateralize ITDs with essentially normal behavioral thresholds near 50 μs. Furthermore, comparable ND rats show high physiological sensitivity to ITDs immediately after binaural implantation in adulthood. Our result that ND-CI rats achieved very good behavioral ITD thresholds, while prelingually deaf human CI patients often fail to develop a useful sensitivity to ITD raises urgent questions concerning the possibility that shortcomings in technology or treatment, rather than missing input during early development, may be behind the usually poor binaural outcomes for current CI patients.

Consistent and chronic cochlear implant use partially reverses cortical effects of single sided deafness in children

Potentially neuroprotective effects of CI use were studied in 22 children with single sided deafness (SSD). Auditory-evoked EEG confirmed strengthened representation of the intact ear in the ipsilateral auditory cortex at initial CI activation in children with early-onset SSD (n = 15) and late-onset SSD occurring suddenly in later childhood/adolescence (n = 7). In early-onset SSD, representation of the hearing ear decreased with chronic CI experience and expected lateralization to the contralateral auditory cortex from the CI increased with longer daily CI use. In late-onset SSD, abnormally high activity from the intact ear in the ipsilateral cortex reduced, but responses from the deaf ear weakened despite CI use. Results suggest that: (1) cortical reorganization driven by unilateral hearing can occur throughout childhood; (2) chronic and consistent CI use can partially reverse these effects; and (3) CI use may not protect children with late-onset SSD from ongoing deterioration of pathways from the deaf ear.

Hearing Loss in Children: A Review

IMPORTANCE

Hearing loss in children is common and by age 18 years, affects nearly 1 of every 5 children. Without hearing rehabilitation, hearing loss can cause detrimental effects on speech, language, developmental, educational, and cognitive outcomes in children.

OBSERVATIONS

Consequences of hearing loss in children include worse outcomes in speech, language, education, social functioning, cognitive abilities, and quality of life. Hearing loss can be congenital, delayed onset, or acquired with possible etiologies including congenital infections, genetic causes including syndromic and nonsyndromic etiologies, and trauma, among others. Evaluation of hearing loss must be based on suspected diagnosis, type, laterality and degree of hearing loss, age of onset, and additional variables such as exposure to cranial irradiation. Hearing rehabilitation for children with hearing loss may include use of hearing aids, cochlear implants, bone anchored devices, or use of assistive devices such as frequency modulating systems.

CONCLUSIONS AND RELEVANCE

Hearing loss in children is common, and there has been substantial progress in diagnosis and management of these cases. Early identification of hearing loss and understanding its etiology can assist with prognosis and counseling of families. In addition, awareness of treatment strategies including the many hearing device options, cochlear implant, and assistive devices can help direct management of the patient to optimize outcomes.

Impact of the sensory environment on balance in children with bilateral cochleovestibular loss

BACKGROUND

The aim of the present study was to determine the role of auditory and visual sensory input on balance in children with bilateral cochlevestibular loss. The prevalence of vestibular impairment, and specifically bilateral vestibular loss (BVL) in children with sensorineural hearing loss (SNHL) is high and children with profound cochleovestibular loss (SNHL-BVL) have impaired balance (Suarez et al., 2007; Suarez et al., 2019). Given that both hearing and vestibular impairments are often congenital or acquired in early life, it remains difficult to tease out the individual developmental impact of either one on balance and spatial awareness in children who experience both of these sensory deficits. While cochlear implants (CI) can provide or restore access to sound in children with SNHL-BVL, there is currently no vestibular prosthetic available for clinical use in this population. These children may also use their intact sensory inputs (i.e. vision) to a greater extent to support balance. Alternately, restoring or providing access to sound may, on its own, help these children to balance better. We hypothesized that balance in children with SNHL-BVL who use bilateral CIs is: 1) improved in the presence of directional sound and 2) impaired when visual cues are dynamic (moving) rather than static.

METHODS

Balance was assessed in 18 children with SNHL-BVL and 34 typically developing children with intact vestibular function and normal hearing by performing the Bruininks-Oseretsky Test of Motor Proficiency-2 (BOT-2) balance subtest in a virtual-reality simulator under 4 sensory conditions of graded complexity. Randomized conditions combined 2 auditory (moving directional street sounds vs. directionless static white noise) and 2 visual (dynamic street scene vs. stationary street scene) stimuli designed to recreate a "real-world" busy downtown street. Balance ability in children with SNHL-BVL was also compared with CI on and off.

RESULTS

As expected and similar to previous work, balance was significantly worse in the children with SNHL-BVL compared to typically developing children in all sensory conditions (p<0.0001). As a group, the mean balance skills of the children with SNHL-BVL were equivalent to that of a 4.4-year-old child despite being much older (mean age =13.8 years). Balance ability improved slightly but significantly when children with SNHL-BVL had access to any sound through their CI (p=0.047) and was positively correlated with duration of implant use (p=0.02). Balance ability did not change further in the presence of moving directional sounds compared to static white noise (p=0.42), or when coupled to a moving visual environment (p=0.32) in children with SNHL-BVL, however opposite to what was hypothesized, in the typically developing group, there was a decrement in performance that occurred in the presence of moving directional sound compared to directionless, static white noise (p=0.02).

CONCLUSIONS

Balance ability in children with SNHL-BVL who use bilateral CI was, as expected, poorer than their typically developing peers in all sensory conditions but improved slightly when they had access to any sound through their implants, with this benefit increasing as duration of implant use increased. This suggests that providing sound inputs through bilateral CIs positively affects balance in children with SNHL-BVL where vestibular and/or auditory inputs are compromised. This benefit was achieved even with auditory inputs that were devoid of moving directional cues (i.e. directionless static white noise) and is consistent with poor spatial hearing in children using bilateral CI.

Functional hearing quality in prelingually deaf school-age children and adolescents with cochlear implants

OBJECTIVE

This study investigated differences in functional hearing quality between youth with cochlear implants (CIs) and normal hearing (NH) peers, as well as associations between functional hearing quality and audiological measures, speech perception, language and executive functioning (EF).

DESIGN

Youth with CIs and NH peers completed measures of audiological functioning, speech perception, language and EF. Parents completed the Quality of Hearing Scale (QHS), a questionnaire measure of functional hearing quality.

STUDY SAMPLE

Participants were 43 prelingually-deaf, early-implanted, long-term CI users and 43 NH peers aged 7-17 years.

RESULTS

Compared to NH peers, youth with CIs showed poorer functional hearing quality on the QHS Speech, Localization, and Sounds subscales and more hearing effort on the QHS Effort subscale. QHS scores did not correlate significantly with audiological/hearing history measures but were significantly correlated with most speech perception, language and EF scores in the CI sample. In the NH sample, QHS scores were uncorrelated with speech perception and language and were inconsistently correlated with EF.

CONCLUSIONS

The QHS is a valid measure of functional hearing quality that is distinct from office-based audiometric or hearing history measures. Functional hearing outcomes are associated with speech-language and EF outcomes in CI users.

Auditory Attention and Spatial Unmasking in Children With Cochlear Implants

The ability to attend to target speech in background noise is an important skill, particularly for children who spend many hours in noisy environments. Intelligibility improves as a result of spatial or binaural unmasking in the free-field for normal-hearing children; however, children who use bilateral cochlear implants (BiCIs) demonstrate little benefit in similar situations. It was hypothesized that poor auditory attention abilities might explain the lack of unmasking observed in children with BiCIs. Target and interferer speech stimuli were presented to either or both ears of BiCI participants via their clinical processors. Speech reception thresholds remained low when the target and interferer were in opposite ears, but they did not show binaural unmasking when the interferer was presented to both ears and the target only to one ear. These results demonstrate that, in the most extreme cases of stimulus separation, children with BiCIs can ignore an interferer and attend to target speech, but there is weak or absent binaural unmasking. It appears that children with BiCIs mostly experience poor encoding of binaural cues rather than deficits in ability to selectively attend to target speech.

Evaluating the Impact of Age, Acoustic Exposure, and Electrical Stimulation on Binaural Sensitivity in Adult Bilateral Cochlear Implant Patients

Deafness in both ears is highly disruptive to communication in everyday listening situations. Many individuals with profound deafness receive bilateral cochlear implants (CIs) to gain access to spatial cues used in localization and speech understanding in noise. However, the benefit of bilateral CIs, in particular sensitivity to interaural time and level differences (ITD and ILDs), varies among patients. We measured binaural sensitivity in 46 adult bilateral CI patients to explore the relationship between binaural sensitivity and three classes of patient-related factors: age, acoustic exposure, and electric hearing experience. Results show that ILD sensitivity increased with shorter years of acoustic exposure, younger age at testing, or an interaction between these factors, moderated by the duration of bilateral hearing impairment. ITD sensitivity was impacted by a moderating effect between years of bilateral hearing impairment and CI experience. When age at onset of deafness was treated as two categories (<18 vs. >18 years of age), there was no clear effect for ILD sensitivity, but some differences were observed for ITD sensitivity. Our findings imply that maximal binaural sensitivity is obtained by listeners with a shorter bilateral hearing impairment, a longer duration of CI experience, and potentially a younger age at testing. 198/200.

The Effect of Cochlear Implant Interval on Spoken Language Skills of Pediatric Bilateral Cochlear Implant Users

OBJECTIVE

To examine the effects of cochlear implant (CI) interval (time between CI surgeries) on receptive vocabulary and receptive language skills for children with bilateral CIs.

STUDY DESIGN

A prospective cross-sectional study design.

SETTING

Participants were recruited from, and tested at, oral schools for the deaf and pediatric audiology clinics across the United States.

PATIENTS

Eighty-eight children, 4 to 9 years of age, with bilateral CIs and known hearing histories. Twenty-three participants received CIs simultaneously and 65 received CIs sequentially. Of those implanted sequentially, 86% wore a hearing aid (HA) on the non-implanted ear during the CI interval.

INTERVENTION

Bilateral cochlear implantation.

MAIN OUTCOME MEASURES

Receptive vocabulary was measured via the Peabody Picture Vocabulary Test (PPVT). Receptive language skills were measured via the Clinical Evaluation of Language Fundamentals (CELF).

RESULTS

Multiple linear regression models indicate better receptive vocabulary and receptive language skills are associated with earlier ages at first CI (CI 1), but not with shorter CI intervals.

CONCLUSIONS

Early cochlear implantation (i.e., age at CI 1) is critical for better receptive vocabulary and receptive language skills. Shorter CI intervals are not associated with better receptive vocabulary and receptive language skills for these 88 children, who nearly all used bimodal hearing during the interval. Use of a HA at the non-implanted ear, before receipt of a second CI (CI 2), may mitigate the effects of early bilateral auditory deprivation.

Reading and Theory of Mind in Adolescents with Cochlear Implant

Previous research has shown a possible link between reading comprehension and theory of mind (ToM), but these findings are unclear in adolescents with cochlear implants (CI). In the present study, reading comprehension and ToM were assessed in adolescents with CI and the relation between both skills was also studied. Two sessions were performed on two groups of adolescents aged between 12 and 16 years of age (36 adolescents with CI and 54 participants with typical hearing, TH). They were evaluated by means of a standardized reading battery, a false belief task, and Faux Pas stories. The results indicated that reading and cognitive ToM were more developed in the TH group than in adolescents with CI. However, early-CI and binaural group performance were close to the TH group in narrative and expository comprehension and cognitive ToM. The results also indicated that cognitive ToM and reading comprehension appear to be related in deaf adolescents.

Auditory processing disorders in incarcerated youth: A call for early detection and treatment

BACKGROUND

Numerous reports have linked language impairment, academic underachievement, and attention disorder to misbehavior in adolescence. Recent studies have found an association between deficits in hearing and auditory processing and involvement in the juvenile justice system. In fact, the existence of an auditory processing disorder (APD) is a risk factor for adolescent delinquency even in the presence of normal hearing. The nexus between APD, low academic achievement and offending behavior in teens has prompted recommendation for early screening of school children for abnormalities in auditory processing. Using a variety of diagnostic tools, investigators have found an increase in the frequency of APD in cohorts of confined youthful offenders. The present investigation evaluates the prevalence of APD in a group of incarcerated youth residing in a detention center.

METHODS

A total of 52 incarcerated adolescents (8 females and 44 males; age range 13-20 (M = 16.0), residing at a juvenile detention center in Pittsburgh, Pennsylvania and determined to have normal auditory acuity were included in the study. All participants were screened for APD using two dichotic listening tests, the Randomized Dichotic Digits Test (RDDT) and the Dichotic Words Test (DWT), evaluative modalities to identify deficits in auditory processing. The prevalence of APD in the study group was compared to previously published normative data for non-offending age-matched youth.

RESULTS

On the RDDT, 23.1% of participants demonstrated normal auditory processing, while 77% had abnormal test results. On the DWT, 75% of subjects exhibited normal auditory processing, while the scores were abnormal for 24.9%. When the results of the RDDT and the DWT were combined to establish a pattern for the purpose of interpreting a deficit, 21.1% of the participants produced results that were within normal limits, while 17.3% qualified for a diagnosis of APD, with abnormal results on both tests. Previous studies have estimated the prevalence of auditory processing disorder in the general adolescent population as being between 2% and 7%.

CONCLUSIONS

This study found a higher prevalence of auditory processing disorder in a cohort of incarcerated youth compared with age-matched controls. Diagnostic screening protocols that identify at-risk children have been developed, as have effective therapies to improve auditory processing function. Teachers, pediatricians and psychologists should consider APD in children and adolescents with behaviors that may increase their risk for juvenile justice involvement. Studies on optimal timing and strategies for assessing and treating APD in children and adolescents are needed, including youth caught up in the juvenile justice system.

Binaural hearing is impaired in children with hearing loss who use bilateral hearing aids

This paper asked whether children fitted with bilateral hearing aids (BHA) develop normal perception of binaural cues which are the basis of spatial hearing. Data from children with BHA (n = 26, age = 12.6 ± 2.84 years) were compared to data from a control group (n = 12, age = 12.36 ± 2.83 years). Stimuli were 250 Hz click-trains of 36 ms and a 40 ms consonant-vowel /da/ at 1 Hz presented through ER3A insert-earphones unilaterally or bilaterally. Bilateral stimuli were presented at different interaural level difference (ILD) and interaural timing difference (ITD) conditions. Participants indicated whether the sound came from the left or right side (lateralization) or whether one sound or two could be heard (binaural fusion). BHA children lateralized ILDs similarly to the control group but had impaired lateralization of ITDs. Longer response times relative to controls suggest that lateralization of ITDs was challenging for children with BHA. Most, but not all, of the BHA group were able to fuse click and speech sounds similarly to controls. Those unable to fuse showed particularly poor ITD lateralization. Results suggest that ITD perception is abnormal in children using BHAs, suggesting persistent effects of hearing loss that are not remediated by present clinical rehabilitation protocols.

Effects of Early Acoustic Hearing on Speech Perception and Language for Pediatric Cochlear Implant Recipients

Purpose The overall goal of the current study was to identify an optimal level and duration of acoustic experience that facilitates language development for pediatric cochlear implant (CI) recipients-specifically, to determine whether there is an optimal duration of hearing aid (HA) use and unaided threshold levels that should be considered before proceeding to bilateral CIs. Method A total of 117 pediatric CI recipients (ages 5-9 years) were given speech perception and standardized tests of receptive vocabulary and language. The speech perception battery included tests of segmental perception (e.g., word recognition in quiet and noise, and vowels and consonants in quiet) and of suprasegmental perception (e.g., talker and stress discrimination, and emotion identification). Hierarchical regression analyses were used to determine the effects of speech perception on language scores, and the effects of residual hearing level (unaided pure-tone average [PTA]) and duration of HA use on speech perception. Results A continuum of residual hearing levels and the length of HA use were represented by calculating the unaided PTA of the ear with the longest duration of HA use for each child. All children wore 2 devices: Some wore bimodal devices, while others received their 2nd CI either simultaneously or sequentially, representing a wide range of HA use (0.03-9.05 years). Regression analyses indicate that suprasegmental perception contributes unique variance to receptive language scores and that both segmental and suprasegmental skills each contribute independently to receptive vocabulary scores. Also, analyses revealed an optimal duration of HA use for each of 3 ranges of hearing loss severity (with mean PTAs of 73, 92, and 111 dB HL) that maximizes suprasegmental perception. Conclusions For children with the most profound losses, early bilateral CIs provide the greatest opportunity for developing good spoken language skills. For those with moderate-to-severe losses, however, a prescribed period of bimodal use may be more advantageous for developing good spoken language skills.

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

BACKGROUND

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.

PURPOSE

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.

RESEARCH DESIGN

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.

STUDY SAMPLE

Thirteen children with BiCIs (27-42 months old) and fifteen age-matched (NH).

DATA COLLECTION AND ANALYSIS

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.

RESULTS

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°).

CONCLUSIONS

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.

Evaluating the Long-Term Hearing Outcomes of Cochlear Implant Users With Single-Sided Deafness

OBJECTIVES

To investigate the long-term outcomes of cochlear implantation in individuals with single-sided deafness (SSD) in terms of speech perception, subjective hearing performance, and sound localization.

METHODS

Thirty-four subjects with SSD were recruited across two large cochlear implant (CI) centers (Antwerp, Belgium and Perth, Australia). The long-term hearing outcomes (between 4 and 10 years of CI use) were evaluated using speech in noise tests, a subjective hearing performance questionnaire (Speech, Spatial and Qualities Questionnaire [SSQ12]), and sound localization tests.

RESULTS

Statistically significant improvements were observed in speech perception in noise and sound localization results postoperatively with the use of a CI in comparison to preoperative measurements. Subjective hearing abilities also significantly improved after long-term CI use.

CONCLUSION

Access to binaural hearing is important for subjects with SSD. CI users with SSD experience long-term benefits in speech understanding, sound localization, and quality of life.

The Effect of Simulated Interaural Frequency Mismatch on Speech Understanding and Spatial Release From Masking

OBJECTIVE

The binaural-hearing system interaurally compares inputs, which underlies the ability to localize sound sources and to better understand speech in complex acoustic environments. Cochlear implants (CIs) are provided in both ears to increase binaural-hearing benefits; however, bilateral CI users continue to struggle with understanding speech in the presence of interfering sounds and do not achieve the same level of spatial release from masking (SRM) as normal-hearing listeners. One reason for diminished SRM in CI users could be that the electrode arrays are inserted at different depths in each ear, which would cause an interaural frequency mismatch. Because interaural frequency mismatch diminishes the salience of interaural differences for relatively simple stimuli, it may also diminish binaural benefits for spectral-temporally complex stimuli like speech. This study evaluated the effect of simulated frequency-to-place mismatch on speech understanding and SRM.

DESIGN

Eleven normal-hearing listeners were tested on a speech understanding task. There was a female target talker who spoke five-word sentences from a closed set of words. There were two interfering male talkers who spoke unrelated sentences. Nonindividualized head-related transfer functions were used to simulate a virtual auditory space. The target was presented from the front (0°), and the interfering speech was either presented from the front (colocated) or from 90° to the right (spatially separated). Stimuli were then processed by an eight-channel vocoder with tonal carriers to simulate aspects of listening through a CI. Frequency-to-place mismatch ("shift") was introduced by increasing the center frequency of the synthesis filters compared with the corresponding analysis filters. Speech understanding was measured for different shifts (0, 3, 4.5, and 6 mm) and target-to-masker ratios (TMRs: +10 to -10 dB). SRM was calculated as the difference in the percentage of correct words for the colocated and separated conditions. Two types of shifts were tested: (1) bilateral shifts that had the same frequency-to-place mismatch in both ears, but no interaural frequency mismatch, and (2) unilateral shifts that produced an interaural frequency mismatch.

RESULTS

For the bilateral shift conditions, speech understanding decreased with increasing shift and with decreasing TMR, for both colocated and separate conditions. There was, however, no interaction between shift and spatial configuration; in other words, SRM was not affected by shift. For the unilateral shift conditions, speech understanding decreased with increasing interaural mismatch and with decreasing TMR for both the colocated and spatially separated conditions. Critically, there was a significant interaction between the amount of shift and spatial configuration; in other words, SRM decreased for increasing interaural mismatch.

CONCLUSIONS

A frequency-to-place mismatch in one or both ears resulted in decreased speech understanding. SRM, however, was only affected in conditions with unilateral shifts and interaural frequency mismatch. Therefore, matching frequency information between the ears provides listeners with larger binaural-hearing benefits, for example, improved speech understanding in the presence of interfering talkers. A clinical procedure to reduce interaural frequency mismatch when programming bilateral CIs may improve benefits in speech segregation that are due to binaural-hearing abilities.

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.