Cochlear implants and spoken language processing abilities: review and assessment of the literature

Factors affecting consonant production accuracy in children with cochlear implants: Expressive vocabulary and maternal education

BACKGROUND

Despite the ability of cochlear implants (CIs) to provide children with access to speech, there is considerable variability in spoken language outcomes. Research aimed at identifying factors influencing speech production accuracy is needed.

AIMS

To characterize the consonant production accuracy of children with cochlear implants (CWCI) and an age-matched group of children with typical hearing (CWTH) and to explore several factors that potentially affect the ability of both groups to accurately produce consonants.

METHODS & PROCEDURES

We administered the Bankson-Bernthal Test of Phonology (BBTOP) to a group of 25 CWCI (mean age = 4;9, SD = 1;6, range = 3;2-8;5) implanted prior to 30 months of age with a mean duration of implant usage of 3;6 and an age-matched group of 25 CWTH (mean age = 5;0, SD = 1;6, range = 3;1-8;6). The recorded results were transcribed, and the accuracy of the target consonants was determined. Expressive vocabulary size estimates were obtained from a language sample using the number of different words (NDW). A parent questionnaire provided information about maternal education, duration of CIs experience and other demographic characteristics of each child.

OUTCOMES & RESULTS

The CWCI group demonstrated some similarities to, and some differences from, their hearing peers. The CWCI demonstrated poorer consonant production accuracy overall and in various phonetic categories and word positions. However, both groups produced initial consonants more accurately than final consonants. Whilst CWCI had poorer production accuracy than CWTH for all phonetic categories (stops, nasals, fricatives, affricates, liquids and glides and consonant clusters), both groups exhibited similar error patterns across categories. For CWCI, the factors most related to consonant production accuracy when considered individually were expressive vocabulary size, followed by duration of CI experience, chronological age, maternal education and gender. The combination of maternal education and vocabulary size resulted in the best model of consonant production accuracy for this group. For the CWTH, chronological age followed by vocabulary size were most related to consonant production accuracy. No combination of factors yielded an improved model for the CWTH.

CONCLUSIONS & IMPLICATIONS

Whilst group differences in production accuracy between the CWCI and CWTH were found, the pattern of errors was similar for the two groups of children, suggesting that the children are at earlier stages of overall consonant production development. Although duration of CI experience was a significant covariate in a single-variable model of consonant production accuracy for CWCI, the best multivariate model of consonant production accuracy for these children was based on the combination of expressive vocabulary size and maternal education.

WHAT THIS PAPER ADDS

What is already known on the subject Research has shown that a range of factors is associated with consonant production accuracy by CWCIs, including factors such as the age at implant, duration of implant use, gender, other language skills and maternal education. Despite numerous studies that have examined speech sound production in these children, most have explored a limited number of factors that might explain the variability in scores obtained. Research that examines the potential role of a range of child-related and environmental factors in the same children is needed to determine the predictive role of these factors in speech production outcomes. What this paper adds to the existing knowledge Whilst the consonant production accuracy was lower for the CWCIs than for their typically hearing peers, there were some similarities suggesting that these children are experiencing similar, but delayed, acquisition of consonant production skills to that of their hearing peers. Whilst several factors are predictive of consonant production accuracy in children with implants, vocabulary diversity and maternal education, an indirect measure of socio-economic status, were the best combined predictors of consonant production accuracy. What are the potential or actual clinical implications of this work? Understanding the factors that shape individual differences in CWCI speech production is important for effective clinical decision-making and intervention planning. The present findings point to two potentially important factors related to speech sound production beyond the duration of robust hearing in CWCI, namely, a lexical diversity and maternal education. This suggests that intervention is likely most efficient that addresses both vocabulary development and speech sound development together. The current findings further suggest the importance of parental involvement and commitment to spoken language development and the importance of receiving early and consistent intervention aimed both at skill development and parental efficacy.

The effect of retrieval practice on vocabulary learning for DHH children

On average, deaf and hard-of-hearing (DHH) children have difficulty developing expressive spoken vocabulary comparable to hearing peers. Yet, there are no evidence-based practices to guide classroom instruction for teachers of the deaf. Retrieval practice-a robust learning strategy-has been shown to improve children's retention of vocabulary, but it has not been investigated with DHH children who use listening and spoken language. The present study examined whether DHH children benefit from using retrieval practice to learn new vocabulary. Sixteen DHH children (in the age range of 5.0-8.11 years) were taught a set of new vocabulary words using retrieval practice or repeated exposure. A recall test was administered two days later. Results showed that DHH children were twice as likely to recall a word taught through retrieval practice than exposure (OR = 2.01, p = .02). Presence of an additional diagnosis and number of practice trials were also significant predicting factors of vocabulary learning.

Differentiating Language for Students Who Are Deaf or Hard of Hearing: A Practice-Informed Framework for Auditory and Visual Supports

PURPOSE

Speech-language pathologists (SLPs) serving students who are d/Deaf or hard of hearing (Deaf/hh) and their deaf education counterparts must navigate complexities in language that include modalities that are spoken or signed and proficiency, which is often compromised. This tutorial describes a practice-informed framework that conceptualizes and organizes a continuum of auditory and visual language supports with the aim of informing the practice of the SLP whose training is more inherently focused on spoken language alone, as well as the practice of the teacher of the Deaf/hh (TDHH) who may focus more on visual language supports.

METHOD

This product resulted from a need within interdisciplinary, graduate programs for SLPs and TDHHs. Both cohorts required preparation to address the needs of diverse language learners who are Deaf/hh. This tutorial includes a brief review of the challenges in developing language proficiency and describes the complexities of effective service delivery. The process of developing a practice-informed framework for language supports is summarized, referencing established practices in auditory-based and visually based methodologies, identifying parallel practices, and summarizing the practices within a multitiered framework called the Framework of Differentiated Practices for Language Support. Recommendations for use of the framework include guidance on the identification of a student's language modality/ies and proficiency to effectively match students' needs and target supports.

CONCLUSIONS

An examination of established practices in language supports across auditory and visual modalities reveals clear parallels that can be organized into a tiered framework. The result is a reference for differentiating language for the interdisciplinary school team. The parallel supports also provide evidence of similarities in practice across philosophical boundaries as professionals work collaboratively.

Predicting emotion perception abilities for cochlear implant users

OBJECTIVE

In daily life, failure to perceive emotional expressions can result in maladjusted behaviour. For cochlear implant users, perceiving emotional cues in sounds remains challenging, and the factors explaining the variability in patients' sensitivity to emotions are currently poorly understood. Understanding how these factors relate to auditory proficiency is a major challenge of cochlear implant research and is critical in addressing patients' limitations.

DESIGN

To fill this gap, we evaluated different auditory perception aspects in implant users (pitch discrimination, music processing and speech intelligibility) and correlated them to their performance in an emotion recognition task.

STUDY SAMPLE

Eighty-four adults (18-76 years old) participated in our investigation; 42 cochlear implant users and 42 controls. Cochlear implant users performed worse than their controls on all tasks, and emotion perception abilities were correlated to their age and their clinical outcome as measured in the speech intelligibility task.

RESULTS

As previously observed, emotion perception abilities declined with age (here by about 2-3% in a decade). Interestingly, even when emotional stimuli were musical, CI users' skills relied more on processes underlying speech intelligibility.

CONCLUSIONS

These results suggest that speech processing remains a clinical priority even when one is interested in affective skills.

Diagnostic value of preoperative measures in selecting post-lingually deafened candidates for cochlear implantation - a different approach

OBJECTIVES

We examined which preoperative diagnostic measure is most suited to serve as a selection criterion to determine adult cochlear implantation (CI) candidacy.

DESIGN

Preoperative diagnostic measures included pure tone audiometry (PTA; 0.5, 1, 2, 4 kHz), speech perception tests (SPT) unaided with headphones and with best-aided hearing aids (in quiet and in noise). Gain in speech perception was used as outcome measure. Performance of preoperative measures was analysed using the area under the curve (AUC) of receiver operating characteristic (ROC) curves.

STUDY SAMPLE

This retrospective longitudinal cohort study included 552 post-lingually deafened adults with CI in a tertiary referral centre in the Netherlands.

RESULTS

Best-aided SPT in quiet was the most accurate in defining which CI candidates improved their speech perception in quiet postoperatively. For an improvement in speech perception in noise, the best-aided SPT in noise was the most accurate in defining which adult would benefit from CI. PTA measures performed lower compared to the SPT measures.

CONCLUSIONS

SPT is better than PTA for selecting CI candidates who will benefit in terms of speech perception. Best-aided SPT in noise was the most accurate for indicating an improvement of speech perception in noise but was only evaluated in high performers with residual hearing. These insights will assist in formulating more effective selection criteria for CI.

Semantic processing in children with Cochlear Implants: A review of current N400 studies and recommendations for future research

Deaf and hard of hearing children with cochlear implants (CI) often display impaired spoken language skills. While a large number of studies investigated brain responses to sounds in this population, relatively few focused on semantic processing. Here we summarize and discuss findings in four studies of the N400, a cortical response that reflects semantic processing, in children with CI. A study with auditory target stimuli found N400 effects at delayed latencies at 12 months after implantation, but at 18 and 24 months after implantation effects had typical latencies. In studies with visual target stimuli N400 effects were larger than or similar to controls in children with CI, despite lower semantic abilities. We propose that in children with CI, the observed large N400 effect reflects a stronger reliance on top-down predictions, relative to bottom-up language processing. Recent behavioral studies of children and adults with CI suggest that top-down processing is a common compensatory strategy, but with distinct limitations such as being effortful. A majority of the studies have small sample sizes (N < 20), and only responses to image targets were studied repeatedly in similar paradigms. This precludes strong conclusions. We give suggestions for future research and ways to overcome the scarcity of participants, including extending research to children with conventional hearing aids, an understudied group.

Using x-ray micro computed tomography to quantify intracochlear fibrosis after cochlear implantation in a Guinea pig model

Cochlear implants (CIs) allow individuals with profound hearing loss to understand speech and perceive sounds. However, not all patients obtain the full benefits that CIs can provide and the cause of this disparity is not fully understood. One possible factor for the variability in outcomes after cochlear implantation, is the development of fibrotic scar tissue around the implanted electrode. It has been hypothesised that limiting the extent of fibrosis after implantation may improve overall CI function, and longevity of the device. Currently, histology is often used to quantify the extent of intracochlear tissue growth after implantation however this method is labour intensive, time-consuming, often involves significant user bias, and causes physical distortion of the fibrosis. Therefore, this study aimed to evaluate x-ray micro computed tomography (μCT) as a method to measure the amount and distribution of fibrosis in a guinea pig model of cochlear implantation. Adult guinea pigs were implanted with an inactive electrode, and cochleae harvested eight weeks later (n = 7) and analysed using μCT, to quantify the extent of tissue reaction, followed by histological analysis to confirm that the tissue was indeed fibrotic. Cochleae harvested from an additional six animals following implantation were analysed by μCT, before and after contrast staining with osmium tetroxide (OsO4), to enhance the visualisation of soft tissues within the cochlea, including the tissue reaction. Independent analysis by two observers showed that the quantification method was robust and provided additional information on the distribution of the response within the cochlea. Histological analysis revealed that μCT visualised dense collagenous material and new bone formation but did not capture loose, areolar fibrotic tissue. Treatment with OsO4 significantly enhanced the visible tissue reaction detected using μCT. Overall, μCT is an alternative and reliable method that can be used to quantify the extent of the CI-induced intracochlear tissue response and will be a useful tool for the in vivo assessment of novel anti-fibrotic treatments.

Learning a Sign Language Does Not Hinder Acquisition of a Spoken Language

PURPOSE

The purpose of this study is to determine whether and how learning American Sign Language (ASL) is associated with spoken English skills in a sample of ASL-English bilingual deaf and hard of hearing (DHH) children.

METHOD

This cross-sectional study of vocabulary size included 56 DHH children between 8 and 60 months of age who were learning both ASL and spoken English and had hearing parents. English and ASL vocabulary were independently assessed via parent report checklists.

RESULTS

ASL vocabulary size positively correlated with spoken English vocabulary size. Spoken English vocabulary sizes in the ASL-English bilingual DHH children in the present sample were comparable to those in previous reports of monolingual DHH children who were learning only English. ASL-English bilingual DHH children had total vocabularies (combining ASL and English) that were equivalent to same-age hearing monolingual children. Children with large ASL vocabularies were more likely to have spoken English vocabularies in the average range based on norms for hearing monolingual children.

CONCLUSIONS

Contrary to predictions often cited in the literature, acquisition of sign language does not harm spoken vocabulary acquisition. This retrospective, correlational study cannot determine whether there is a causal relationship between sign language and spoken language vocabulary acquisition, but if a causal relationship exists, the evidence here suggests that the effect would be positive. Bilingual DHH children have age-expected vocabularies when considering the entirety of their language skills. We found no evidence to support recommendations that families with DHH children avoid learning sign language. Rather, our findings show that children with early ASL exposure can develop age-appropriate vocabulary skills in both ASL and spoken English.

Exploring neurocognitive factors and brain activation in adult cochlear implant recipients associated with speech perception outcomes-A scoping review

Background

Cochlear implants (CIs) are considered an effective treatment for severe-to-profound sensorineural hearing loss. However, speech perception outcomes are highly variable among adult CI recipients. Top-down neurocognitive factors have been hypothesized to contribute to this variation that is currently only partly explained by biological and audiological factors. Studies investigating this, use varying methods and observe varying outcomes, and their relevance has yet to be evaluated in a review. Gathering and structuring this evidence in this scoping review provides a clear overview of where this research line currently stands, with the aim of guiding future research.

Objective

To understand to which extent different neurocognitive factors influence speech perception in adult CI users with a postlingual onset of hearing loss, by systematically reviewing the literature.

Methods

A systematic scoping review was performed according to the PRISMA guidelines. Studies investigating the influence of one or more neurocognitive factors on speech perception post-implantation were included. Word and sentence perception in quiet and noise were included as speech perception outcome metrics and six key neurocognitive domains, as defined by the DSM-5, were covered during the literature search (Protocol in open science registries: 10.17605/OSF.IO/Z3G7W of searches in June 2020, April 2022).

Results

From 5,668 retrieved articles, 54 articles were included and grouped into three categories using different measures to relate to speech perception outcomes: (1) Nineteen studies investigating brain activation, (2) Thirty-one investigating performance on cognitive tests, and (3) Eighteen investigating linguistic skills.

Conclusion

The use of cognitive functions, recruiting the frontal cortex, the use of visual cues, recruiting the occipital cortex, and the temporal cortex still available for language processing, are beneficial for adult CI users. Cognitive assessments indicate that performance on non-verbal intelligence tasks positively correlated with speech perception outcomes. Performance on auditory or visual working memory, learning, memory and vocabulary tasks were unrelated to speech perception outcomes and performance on the Stroop task not to word perception in quiet. However, there are still many uncertainties regarding the explanation of inconsistent results between papers and more comprehensive studies are needed e.g., including different assessment times, or combining neuroimaging and behavioral measures.

Systematic review registration

https://doi.org/10.17605/OSF.IO/Z3G7W.

The 100 Most-Cited Manuscripts in Hearing Implants: A Bibliometrics Analysis

The aim of the study was to characterise the most frequently cited articles on the topic of hearing implants. A systematic search was carried out using the Thomson Reuters Web of Science Core Collection database. Eligibility criteria restricted the results to primary studies and reviews published from 1970 to 2022 in English dealing primarily with hearing implants. Data including the authors, year of publication, journal, country of origin, number of citations and average number of citations per year were extracted, as well as the impact factors and five-year impact factor of journals publishing the articles. The top 100 papers were published across 23 journals and were cited 23,139 times. The most-cited and influential article describes the first use of the continuous interleaved sampling (CIS) strategy utilised in all modern cochlear implants. More than half of the studies on the list were produced by authors from the United States, and the Ear and Hearing journal had both the greatest number of articles and the greatest number of total citations. To conclude, this research serves as a guide to the most influential articles on the topic of hearing implants, although bibliometric analyses mainly focus on citations. The most-cited article was an influential description of CIS.

Deaf Children Need Rich Language Input from the Start: Support in Advising Parents

Bilingual bimodalism is a great benefit to deaf children at home and in schooling. Deaf signing children perform better overall than non-signing deaf children, regardless of whether they use a cochlear implant. Raising a deaf child in a speech-only environment can carry cognitive and psycho-social risks that may have lifelong adverse effects. For children born deaf, or who become deaf in early childhood, we recommend comprehensible multimodal language exposure and engagement in joint activity with parents and friends to assure age-appropriate first-language acquisition. Accessible visual language input should begin as close to birth as possible. Hearing parents will need timely and extensive support; thus, we propose that, upon the birth of a deaf child and through the preschool years, among other things, the family needs an adult deaf presence in the home for several hours every day to be a linguistic model, to guide the family in taking sign language lessons, to show the family how to make spoken language accessible to their deaf child, and to be an encouraging liaison to deaf communities. While such a support program will be complicated and challenging to implement, it is far less costly than the harm of linguistic deprivation.

Recognizing Voices Through a Cochlear Implant: A Systematic Review of Voice Perception, Talker Discrimination, and Talker Identification

OBJECTIVE

Some cochlear implant (CI) users report having difficulty accessing indexical information in the speech signal, presumably due to limitations in the transmission of fine spectrotemporal cues. The purpose of this review article was to systematically review and evaluate the existing research on talker processing in CI users. Specifically, we reviewed the performance of CI users in three types of talker- and voice-related tasks. We also examined the different factors (such as participant, hearing, and device characteristics) that might influence performance in these specific tasks.

DESIGN

We completed a systematic search of the literature with select key words using citation aggregation software to search Google Scholar. We included primary reports that tested (a) talker discrimination, (b) voice perception, and (c) talker identification. Each report must have had at least one group of participants with CIs. Each included study was also evaluated for quality of evidence.

RESULTS

The searches resulted in 1,561 references, which were first screened for inclusion and then evaluated in full. Forty-three studies examining talker discrimination, voice perception, and talker identification were included in the final review. Most studies were focused on postlingually deafened and implanted adult CI users, with fewer studies focused on prelingual implant users. In general, CI users performed above chance in these tasks. When there was a difference between groups, CI users performed less accurately than their normal-hearing (NH) peers. A subset of CI users reached the same level of performance as NH participants exposed to noise-vocoded stimuli. Some studies found that CI users and NH participants relied on different cues for talker perception. Within groups of CI users, there is moderate evidence for a bimodal benefit for talker processing, and there are mixed findings about the effects of hearing experience.

CONCLUSIONS

The current review highlights the challenges faced by CI users in tracking and recognizing voices and how they adapt to it. Although large variability exists, there is evidence that CI users can process indexical information from speech, though with less accuracy than their NH peers. Recent work has described some of the factors that might ease the challenges of talker processing in CI users. We conclude by suggesting some future avenues of research to optimize real-world speech outcomes.

Parameter-Specific Morphing Reveals Contributions of Timbre to the Perception of Vocal Emotions in Cochlear Implant Users

Objectives:

Research on cochlear implants (CIs) has focused on speech comprehension, with little research on perception of vocal emotions. We compared emotion perception in CI users and normal-hearing (NH) individuals, using parameter-specific voice morphing.

Design:

Twenty-five CI users and 25 NH individuals (matched for age and gender) performed fearful-angry discriminations on bisyllabic pseudoword stimuli from morph continua across all acoustic parameters (Full), or across selected parameters (F0, Timbre, or Time information), with other parameters set to a noninformative intermediate level.

Results:

Unsurprisingly, CI users as a group showed lower performance in vocal emotion perception overall. Importantly, while NH individuals used timbre and fundamental frequency (F0) information to equivalent degrees, CI users were far more efficient in using timbre (compared to F0) information for this task. Thus, under the conditions of this task, CIs were inefficient in conveying emotion based on F0 alone. There was enormous variability between CI users, with low performers responding close to guessing level. Echoing previous research, we found that better vocal emotion perception was associated with better quality of life ratings.

Conclusions:

Some CI users can utilize timbre cues remarkably well when perceiving vocal emotions.

Intrinsic mechanical sensitivity of mammalian auditory neurons as a contributor to sound-driven neural activity

Mechanosensation – by which mechanical stimuli are converted into a neuronal signal – is the basis for the sensory systems of hearing, balance, and touch. Mechanosensation is unmatched in speed and its diverse range of sensitivities, reaching its highest temporal limits with the sense of hearing; however, hair cells (HCs) and the auditory nerve (AN) serve as obligatory bottlenecks for sounds to engage the brain. Like other sensory neurons, auditory neurons use the canonical pathway for neurotransmission and millisecond-duration action potentials (APs). How the auditory system utilizes the relatively slow transmission mechanisms to achieve ultrafast speed, and high audio-frequency hearing remains an enigma. Here, we address this paradox and report that the mouse, and chinchilla, AN are mechanically sensitive, and minute mechanical displacement profoundly affects its response properties. Sound-mimicking sinusoidal mechanical and electrical current stimuli affect phase-locked responses. In a phase-dependent manner, the two stimuli can also evoke suppressive responses. We propose that mechanical sensitivity interacts with synaptic responses to shape responses in the AN, including frequency tuning and temporal phase locking. Combining neurotransmission and mechanical sensation to control spike patterns gives the mammalian AN a secondary receptor role, an emerging theme in primary neuronal functions.

Hand Transplants, Daily Functioning, and the Human Capacity for Limb Regeneration

Unlike some of our invertebrate and vertebrate cousins with the capacity to regenerate limbs after traumatic loss, humans do not have the ability to regrow arms or legs lost to injury or disease. For the millions of people worldwide who have lost a limb after birth, the primary route to regaining function and minimizing future complications is via rehabilitation, prosthetic devices, assistive aids, health system robustness, and social safety net structures. The majority of limbs lost are lower limbs (legs), with diabetes and vascular disorders being significant causal contributors. Upper limbs (arms) are lost primarily because of trauma; digits and hands are the most common levels of loss. Even if much of the arm remains intact, upper limb amputation significantly impacts function, largely due to the loss of the hand. Human hands are marvels of evolution and permit a dexterity that enables a wide variety of function not readily replaced by devices. It is not surprising, therefore, for some individuals, dissatisfaction with available prosthetic options coupled with remarkable advances in hand surgery techniques is resulting in patients undertaking the rigors of a hand transplantation. While not “regeneration” in the sense of the enviable ability with which Axolotls can replace a lost limb, hand transplants do require significant regeneration of tissues and nerves. Regaining sophisticated hand functions also depends on “reconnecting” the donated hand with the areas of the human brain responsible for the sensory and motor processing required for complex actions. Human hand transplants are not without controversy and raise interesting challenges regarding the human regenerative capacity and the status of transplants for enabling function. More investigation is needed to address medical and ethical questions prior to expansion of hand transplants to a wider patient population.

Central auditory deficits associated with genetic forms of peripheral deafness

Since the 1990s, the study of inherited hearing disorders, mostly those detected at birth, in the prelingual period or in young adults, has led to the identification of their causal genes. The genes responsible for more than 140 isolated (non-syndromic) and about 400 syndromic forms of deafness have already been discovered. Studies of mouse models of these monogenic forms of deafness have provided considerable insight into the molecular mechanisms of hearing, particularly those involved in the development and/or physiology of the auditory sensory organ, the cochlea. In parallel, studies of these models have also made it possible to decipher the pathophysiological mechanisms underlying hearing impairment. This has led a number of laboratories to investigate the potential of gene therapy for curing these forms of deafness. Proof-of-concept has now been obtained for the treatment of several forms of deafness in mouse models, paving the way for clinical trials of cochlear gene therapy in patients in the near future. Nevertheless, peripheral deafness may also be associated with central auditory dysfunctions and may extend well beyond the auditory system itself, as a consequence of alterations to the encoded sensory inputs or involvement of the causal deafness genes in the development and/or functioning of central auditory circuits. Investigating the diversity, causes and underlying mechanisms of these central dysfunctions, the ways in which they could impede the expected benefits of hearing restoration by peripheral gene therapy, and determining how these problems could be remedied is becoming a research field in its own right. Here, we provide an overview of the current knowledge about the central deficits associated with genetic forms of deafness.

Vocabulary Acquisition as a By-Product of Meaning-Oriented Auditory Training for Children Who Are Deaf or Hard of Hearing

Purpose A meaning-oriented auditory training program for children who are deaf or hard of hearing (d/hh) was assessed with regard to its efficacy in promoting novel word learning. Method While administering the auditory training program, one of the authors (Elizabeth Mauzé) observed that children were learning words they previously did not know. Therefore, we systematically assessed vocabulary gains among 16 children. Most completed pretest, posttest, and retention versions of a picture-naming task in which they attempted to verbally identify 199 color pictures of words that would appear during training. Posttest and retention versions included both pictures used and not used during training in order to test generalization of associations between words and their referents. Importantly, each training session involved meaning-oriented, albeit simple, activities/games on a computer. Results At posttest, the percentage of word gain was 27.3% (SD = 12.5; confidence interval [CI] of the mean: 24.2-30.4) using trained pictures as cues and 25.9% (CI of the mean: 22.9-29.0) using untrained pictures as cues. An analysis of retention scores (for 13 of the participants who completed it weeks later) indicated strikingly high levels of retention for the words that had been learned. Conclusions These findings favor auditory training that is meaning oriented when it comes to the acquisition of different linguistic subsystems, lexis in this case. We also expand the discussion to include other evidence-based recommendations regarding how vocabulary is presented (input-based effects) and what learners are asked to do (task-based effects) as part of an overall effort to help children who are d/hh increase their vocabulary knowledge.

Children with hearing impairment and early cochlear implant: A pragmatic assessment

Extensive research has demonstrated the benefits of cochlear implants (CI) in contributing to improve the linguistic skills of children with hearing impairment; however, few studies have focused on the development of pragmatic ability and its relationship with age of implantation. Pragmatics is the ability to use language in different contexts and its development has crucial implications, e.g., social inclusion and professional attainments. In this study, we conducted a comprehensive assessment of pragmatic ability using the Language Pragmatic Abilities (APL Medea), a battery composed by five different tasks: Comprehension of Metaphors, Implicit meaning, Comics, Situations and Colors Game (a perspective taking task). Eighteen children with early CI, belonging to 3 different age groups (6; 11-7; 11, 8; 0-8; 11 and 9; 0-9; 11 years-old), and twenty-four children with typical development (Control Group) participated to the study. We also investigated how the precocity of CI, i.e., age of first implantation, may affect the pragmatic development. Globally, children with CI obtained lower scores in the APL Medea battery than typically hearing children. However, focusing on the Medea tasks separately, children with CIs differed from their hearing peers only in Comics and Colors Game tasks. Finally, age of implantation was a moderate but significant predictor of pragmatic performance.

[Future therapeutic strategies for olfactory disorders: electrical stimulation, stem cell therapy, and transplantation of olfactory epithelium-an overview]

Passagere oder permanente Riechstörungen können verschiedene Ursachen haben. Ganz aktuell berichtet eine Vielzahl von Patienten im Rahmen von COVID-19-Infektionen über ein fehlendes oder vermindertes Riechvermögen. In der Vergangenheit wurden vielfältige Therapieoptionen untersucht, diese variieren vom Riechtraining über Akupunktur und medikamentöse Therapien bis hin zur transkraniellen Magnetstimulation oder, z. B. bei ausgeprägten qualitativen Riechstörungen, der chirurgischen Resektion der Riechschleimhaut. Die Entwicklung einer bioelektrischen Nase, z. B. in Verbindung mit direkter elektrischer Stimulation des Bulbus olfactorius, oder die Transplantation von Riechschleimhaut oder von Stammzellen stellen Behandlungsmöglichkeiten der Zukunft dar. Die Grundlagen für diese Entwicklungen sowie der Stand des Wissens werden in der vorliegenden Arbeit erläutert.

Positive Parenting Behaviors: Impact on the Early Vocabulary of Infants/Toddlers With Cochlear Implants

Purpose To extend our knowledge about factors influencing early vocabulary development for infants with cochlear implants (CIs), we investigated the impact of positive parenting behaviors (PPBs) from the Indicator of Parent Child Interaction, used in parent-child interactions during everyday activities. Method Implantation age for the sample recruited from CI clinics in Australia ranged from 6 to 10 months for 22 children and from 11 to 21 months for 11 children. Three observation sessions at three monthly intervals were coded for use of PPBs. Children's productive vocabulary, based on the MacArthur-Bates Communicative Development Inventories parent checklist, was collected approximately 6 and 9 months later. A repeated-measures negative binomial generalized linear mixed-effects model was used to investigate associations between the total PPBs per session, covariates (maternal education, gender, and time since implant), and the number of words produced. In follow-up analyses with the PPBs entered separately, variable selection was used to retain only those deemed informative, based on the Akaike information criterion. Results As early as Session 1, associations between the PPBs and vocabulary were identified. Time since implant had a positive effect. For different sessions, specific PPBs (descriptive language, follows child's lead, and acceptance and warmth) were identified as important contributors. Conclusions Complementing previous findings, valuable information was identified about parenting behaviors that are likely to impact positively the early vocabulary of infants with CIs. Of importance is providing parents with information and training in skills that have the potential to help create optimal contexts for promoting their child's early vocabulary development.

Narrative competence in Italian children with cochlear implants: a comparison with children matched by chronological or hearing age

The present study aimed to analyse the narrative competence of a group of Italian children with a bilateral cochlear implant (CI) implanted before 30 months of age. Participants were ten children with CI (aged from 42 to 83 months) and two control groups of typically hearing children one-to-one paired by sex, non-verbal reasoning, and chronological or hearing age. A story generation task, specifically developed to assess narrative skills in children (i.e., the Narrative Competence Task) was used to evaluate both macrostructural and microstructural features of the children's narratives. Results showed that children with CI presented only one significant difference in the macrostructural aspects of narratives compared to typically hearing children matched by hearing age, specifically in the higher number of events told. In addition, concerning microstructural features, the only statistically significant difference was a lower lexical variety in the narratives produced by children with CI than in those produced by typically hearing children matched by chronological age. Both macrostructural and microstructural indices appeared to be related to the hearing age of children with CI. Early CI appeared to play a crucial role in the acquisition of a complex area of language development, as narrative competence.

Bimodal Benefits Revealed by Categorical Perception of Lexical Tones in Mandarin-Speaking Kindergarteners With a Cochlear Implant and a Contralateral Hearing Aid

Purpose Pitch reception poses challenges for individuals with cochlear implants (CIs), and adding a hearing aid (HA) in the nonimplanted ear is potentially beneficial. The current study used fine-scale synthetic speech stimuli to investigate the bimodal benefit for lexical tone categorization in Mandarin-speaking kindergarteners using a CI and an HA in opposite ears. Method The data were collected from 16 participants who were required to complete two classical tasks for speech categorical perception (CP) with CI + HA device condition and CI alone condition. Linear mixed-effects models were constructed to evaluate the identification and discrimination scores across different device conditions. Results The bimodal kindergarteners showed CP for the continuum varying from Mandarin Tone 1 and Tone 2. Moreover, the additional acoustic information from the contralateral HA contributes to improved lexical tone categorization, with a steeper slope, a higher discrimination score of between-category stimuli pair, and an improved peakedness score (i.e., an increased benefit magnitude for discriminations of between-category over within-category pairs) for the CI + HA condition than the CI alone condition. The bimodal kindergarteners with better residual hearing thresholds at 250 Hz level in the nonimplanted ear could perceive lexical tones more categorically. Conclusion The enhanced CP results with bimodal listening provide clear evidence for the clinical practice to fit a contralateral HA in the nonimplanted ear in kindergarteners with unilateral CIs with direct benefits from the low-frequency acoustic hearing.

Impact of visual and auditory deprivation on speech perception and production in adults

Speech perception relies on auditory and visual cues and there are strong links between speech perception and production. We aimed to evaluate the role of auditory and visual modalities on speech perception and production in adults with impaired hearing or sight versus those with normal hearing and sight. We examined speech perception and production of three isolated vowels (/i/, /y/, /u/), which were selected based on their different auditory and visual perceptual saliencies, in 12 deaf adults who used one or two cochlear implants (CIs), 14 congenitally blind adults, and 16 adults with normal sight and hearing. The results showed that the deaf adults who used a CI had worse vowel identification and discrimination perception and they also produced vowels that were less typical or precise than other participants. They had different tongue positions in speech production, which possibly partly explains the poorer quality of their spoken vowels. Blind individuals had larger lip openings and smaller lip protrusions for the rounded vowel and unrounded vowels, compared to the other participants, but they still produced vowels that were similar to those produced by the adults with normal sight and hearing. In summary, the deaf adults, even though they used CIs, had greater difficulty in producing accurate vowel targets than the blind adults, whereas the blind adults were still able to produce accurate vowel targets, even though they used different articulatory strategies.

Parameter-Specific Morphing Reveals Contributions of Timbre and Fundamental Frequency Cues to the Perception of Voice Gender and Age in Cochlear Implant Users

Purpose Using naturalistic synthesized speech, we determined the relative importance of acoustic cues in voice gender and age perception in cochlear implant (CI) users. Method We investigated 28 CI users' abilities to utilize fundamental frequency (F0) and timbre in perceiving voice gender (Experiment 1) and vocal age (Experiment 2). Parameter-specific voice morphing was used to selectively control acoustic cues (F0; time; timbre, i.e., formant frequencies, spectral-level information, and aperiodicity, as defined in TANDEM-STRAIGHT) in voice stimuli. Individual differences in CI users' performance were quantified via deviations from the mean performance of 19 normal-hearing (NH) listeners. Results CI users' gender perception seemed exclusively based on F0, whereas NH listeners efficiently used timbre. For age perception, timbre was more informative than F0 for both groups, with minor contributions of temporal cues. While a few CI users performed comparable to NH listeners overall, others were at chance. Separate analyses confirmed that even high-performing CI users classified gender almost exclusively based on F0. While high performers could discriminate age in male and female voices, low performers were close to chance overall but used F0 as a misleading cue to age (classifying female voices as young and male voices as old). Satisfaction with CI generally correlated with performance in age perception. Conclusions We confirmed that CI users' gender classification is mainly based on F0. However, high performers could make reasonable usage of timbre cues in age perception. Overall, parameter-specific morphing can serve to objectively assess individual profiles of CI users' abilities to perceive nonverbal social-communicative vocal signals.

Global Regulatory Review Needed for Cochlear Implants: A Call for FDA Leadership

INTRODUCTION

Using the United States Food and Drug Administration (FDA) as example, we argue that regulatory agencies worldwide should review their guidance on cochlear implants (CIs).

METHODS

This is a position paper, thus the methods are strictly argumentation. Here we give the motivation for our recommendation. The FDA's original approval of implantation in prelingually deaf children was granted without full benefit of information on language acquisition, on childcaregiver communication, and on the lived experience of being deaf. The CI clinical trials, accordingly, did not address risks of linguistic deprivation, especially when the caregiver's communication is not fully accessible to the prelingually deaf child. Wide variability in the effectiveness of CIs since initial and updated approval has been indicated but has not led to new guidance. Children need to be exposed frequently and regularly to accessible natural language while their brains are still plastic enough to become fluent in any language. For the youngest infants, who are not yet producing anything that could be called language although they might be producing salient social signals (Goldstein et al. Child Dev 80:636-644, 2009), good comprehension of communication from caregiver to infant is critical to the development of language. Sign languages are accessible natural languages that, because they are visual, allow full immersion for deaf infants, and they supply the necessary support for this comprehension. The main language contributor to health outcomes is this combination of natural visual language and comprehension in communication. Accordingly, in order to prevent possible language deprivation, all prelingually deaf children should be exposed to both sign and spoken languages when their auditory status is detected, with sign language being critical during infancy and early childhood. Additionally, all caregivers should be given support to learn a sign language if it is new to them so that they can comprehend their deaf children's language expressions fully. However, both languages should be made accessible in their own right, not combined in a simultaneous or total communication approach since speaking one language and signing the other at the same time is problematic.

RESULTS

Again, because this is a position paper, our results are our recommendations. We call for the FDA (and similar agencies in other countries) to review its approval of cochlear implantation in prelingually deaf children who are within the sensitive period for language acquisition. In the meantime, the FDA should require manufacturers to add a highlighted warning to the effect that results with CI vary widely and CIs should not be relied upon to provide adequate auditory input for complete language development in all deaf children. Recent best information on users' experience with CIs (including abandonment) should be clearly provided so that informed decisions can be made. The FDA should require manufacturers' guidance and information materials to include encouragement to parents of deaf children to offer auditory input of a spoken language and visual input of a sign language and to have their child followed closely from birth by developmental specialists in language and cognition. In this way parents can align with providers to prioritize cognitive development and language access in both audio-vocal and visuo-gestural modalities.

DISCUSSION

The arguments and recommendations in this paper are discussed at length as they come up.

Evaluating hearing performance with cochlear implants within the same patient using daily randomization and imaging-based fitting - The ELEPHANT study

Background

Prospective research in the field of cochlear implants is hampered by methodological issues and small sample sizes. The ELEPHANT study presents an alternative clinical trial design with a daily randomized approach evaluating individualized tonotopical fitting of a cochlear implant (CI).

Methods

A single-blinded, daily-randomized clinical trial will be implemented to evaluate a new imaging-based CI mapping strategy. A minimum of 20 participants will be included from the start of the rehabilitation process with a 1-year follow-up period. Based on a post-operative cone beam CT scan (CBCT), mapping of electrical input will be aligned to natural place-pitch arrangement in the individual cochlea. The CI’s frequency allocation table will be adjusted to match the electrical stimulation of frequencies as closely as possible to corresponding acoustic locations in the cochlea. A randomization scheme will be implemented whereby the participant, blinded to the intervention allocation, crosses over between the experimental and standard fitting program on a daily basis, and thus effectively acts as his own control, followed by a period of free choice between both maps to incorporate patient preference. With this new approach the occurrence of a first-order carryover effect and a limited sample size is addressed.

Discussion

The experimental fitting strategy is thought to give rise to a steeper learning curve, result in better performance in challenging listening situations, improve sound quality, better complement residual acoustic hearing in the contralateral ear and be preferred by recipients of a CI. Concurrently, the suitability of the novel trial design will be considered in investigating these hypotheses.

Trial registration

ClinicalTrials.gov: NCT03892941. Registered 27 March 2019.

Lexical Repetition Properties of Caregiver Speech and Language Development in Children With Cochlear Implants

Purpose Early language input plays an important role in child language and cognitive development (e.g., Gilkerson et al., 2018; Hart & Risley, 1995). In this study, we examined the effects of child's hearing status on lexical repetition properties of speech produced by their caregivers with normal hearing (NH). In addition, we investigated the relationship between maternal lexical repetition properties and later language skills in English-learning infants with cochlear implants (CIs). Method In a free-play session, 17 mothers and their prelingually deaf infants who received CIs before 2 years of age (CI group) were recorded at two post-CI intervals: 3 and 6 months postactivation; 18 hearing experience-matched infants with NH and their mothers and 14 chronological age-matched infants with NH group and their mothers were matched to the CI group. Maternal speech was transcribed from the recordings, and measures of maternal lexical repetition were obtained. Standardized language assessments were administered on children with CIs approximately two years after CI activation. Results The findings indicated that measures of lexical repetition were similar among the three groups of mothers, regardless of the hearing status of their infants. In addition, lexical repetition measures were correlated with later language skills in infants with CIs. Conclusions Infants with CIs receive the language input that contains similar lexical repetition properties as that in the speech received by their peers with NH, which is likely to play an important role in child speech processing and language development. These findings provide the knowledge for professionals to coach parents to implement specific language intervention strategies to support language development in infants with hearing loss. Supplemental Material https://doi.org/10.23641/asha.11936322.

Probing and predicting ganglion cell responses to smooth electrical stimulation in healthy and blind mouse retina

Retinal implants are used to replace lost photoreceptors in blind patients suffering from retinopathies such as retinitis pigmentosa. Patients wearing implants regain some rudimentary visual function. However, it is severely limited compared to normal vision because non-physiological stimulation strategies fail to selectively activate different retinal pathways at sufficient spatial and temporal resolution. The development of improved stimulation strategies is rendered difficult by the large space of potential stimuli. Here we systematically explore a subspace of potential stimuli by electrically stimulating healthy and blind mouse retina in epiretinal configuration using smooth Gaussian white noise delivered by a high-density CMOS-based microelectrode array. We identify linear filters of retinal ganglion cells (RGCs) by fitting a linear-nonlinear-Poisson (LNP) model. Our stimulus evokes spatially and temporally confined spiking responses in RGC which are accurately predicted by the LNP model. Furthermore, we find diverse shapes of linear filters in the linear stage of the model, suggesting diverse preferred electrical stimuli of RGCs. The linear filter base identified by our approach could provide a starting point of a model-guided search for improved stimuli for retinal prosthetics.

Capability of deaf children with a cochlear implant

INTRODUCTION

The main idea underlying this paper is that impairments such as deafness are particularly relevant to the extent that they lead to deprivation of capability. Likewise, the impact of healthcare services such as cochlear implants and subsequent rehabilitation can best be inferred from the extent that they protect or restore capability of those affected.

METHODS

To explore children's post-implant capabilities, we tested two newly developed digital, adaptive child self-report and parent-report questionnaires in 19 deaf children (aged 8-12 years) and their parents during rehabilitation, as well as in 23 age peers with normal hearing.

RESULTS

Despite the impressive speech-language results that were recorded with cochlear implants, the post-implant capabilities of the deaf children we evaluated differed from those of their hearing peers, with the cochlear implant group appearing particularly disadvantaged in areas such as accessing information, communication, social participation, and participation in school.

CONCLUSION

Deaf children with cochlear implants who are performing well on linguistic and auditory tests can still experience serious limitations in desired functioning. Our findings suggest that a capability approach may reveal aspects of what is being achieved through rehabilitation that might otherwise remain unnoticed, and that could help to further improve the well-being of our patients.IMPLICATIONS FOR REHABILITATIONOverall, children with cochlear implants appeared disadvantaged in certain capability areas, like accessing information, communication, social participation, and participation in school.It may be worthwhile to also ascertain capabilities in these children, representing a domain not covered by clinical measures, tapping directly into areas that are valuable to the patient.

Early Deafened, Late Implanted Cochlear Implant Users Appreciate Music More Than and Identify Music as Well as Postlingual Users

Introduction: Typical cochlear implant (CI) users, namely postlingually deafened and implanted, report to not enjoy listening to music, and find it difficult to perceive music. Another group of CI users, the early-deafened (during language acquisition) and late-implanted (after a long period of auditory deprivation; EDLI), report a higher music appreciation, but is this related to a better music perception?

Materials and Methods: Sixteen EDLI and fifteen postlingually deafened (control group) CI users participated in the study. The inclusion criteria for EDLI were: severe or profound hearing loss onset before the age of 6 years, implantation after the age of 16 years, and CI experience more than 1 year. Subjectively, music perception and appreciation was evaluated using the Dutch Musical Background Questionnaire. Behaviorally, music perception was measured with melodic contour identification (MCI), using two instruments (piano and organ), each tested with and without a masking contour. Semitone distance between successive tones of the target varied from 1 to 3 semitones.

Results: Subjectively, the EDLI group reported to appreciate music more than postlingually deafened CI users. Behaviorally, while clinical phoneme recognition test score on average was lower in the EDLI group, melodic contour identification did not significantly differ between the two groups. There was, however, an effect of instrument and masker for both groups; the piano was the best-recognized instrument, and for both instruments, the masker with non-overlapping pitch was best recognized.

Discussion: EDLI group reported higher appreciation of music than postlingual control group, even though behaviorally measured music perception did not differ significantly between the two groups. Both surprising findings since EDLI CI users would be expected to have lower outcomes based on the early deafness onset, long duration of auditory deprivation, and on average lower clinical speech scores. Perhaps, the music perception difficulty comes from similar electric hearing limitations in both groups. The higher subjective appreciation in EDLI might be due to the lack of a musical memory, with no ability to compare music heard via the CI to acoustic music perception. Overall, our findings support a benefit from implantation for a positive music experience in EDLI CI users.

Morphological Accuracy in the Speech of Bimodal Bilingual Children with CIs

Sign language use in the (re)habilitation of children with cochlear implants (CIs) remains a controversial issue. Concerns that signing impedes spoken language development are based on research comparing children exposed to spoken and signed language (bilinguals) to children exposed only to speech (monolinguals), although abundant research demonstrates that bilinguals and monolinguals differ in language development. We control for bilingualism effects by comparing bimodal bilingual (signing-speaking) children with CIs (BB-CI) to those with typical hearing (BB-TH). Each child had at least one Deaf parent and was exposed to ASL from birth. The BB-THs were exposed to English from birth by hearing family members, while the BB-CIs began English exposure after cochlear implantation around 22-months-of-age. Elicited speech samples were analyzed for accuracy of English grammatical morpheme production. Although there was a trend toward lower overall accuracy in the BB-CIs, this seemed driven by increased omission of the plural -s, suggesting an exaggerated role of perceptual salience in this group. Errors of commission were rare in both groups. Because both groups were bimodal bilinguals, trends toward group differences were likely caused by delayed exposure to spoken language or hearing through a CI, rather than sign language exposure.

Categorization of everyday sounds by cochlear implanted children

Auditory categorization is an important process in the perception and understanding of everyday sounds. The use of cochlear implants (CIs) may affect auditory categorization and result in poor abilities. The current study was designed to compare how children with normal hearing (NH) and children with CIs categorize a set of everyday sounds. We tested 24 NH children and 24 children with CI on a free-sorting task of 18 everyday sounds corresponding to four a priori categories: nonlinguistic human vocalizations, environmental sounds, musical sounds, and animal vocalizations. Multiple correspondence analysis revealed considerable variation within both groups of child listeners, although the human vocalizations and musical sounds were similarly categorized. In contrast to NH children, children with CIs categorized some sounds according to their acoustic content rather than their associated semantic information. These results show that despite identification deficits, children with CIs are able to categorize environmental and vocal sounds in a similar way to NH children, and are able to use categorization as an adaptive process when dealing with everyday sounds.

Which Questions Do Children With Cochlear Implants Understand? An Eye-Tracking Study

Purpose The purpose of this study was to investigate the processing of morphosyntactic cues (case and verb agreement) by children with cochlear implants (CIs) in German which-questions, where interpretation depends on these morphosyntactic cues. The aim was to examine whether children with CIs who perceive the different cues also make use of them in speech comprehension and processing in the same way as children with normal hearing (NH). Method Thirty-three children with CIs (age 7;01-12;04 years;months, M = 9;07, bilaterally implanted before age 3;3) and 36 children with NH (age 7;05-10;09 years, M = 9;01) received a picture selection task with eye tracking to test their comprehension of subject, object, and passive which-questions. Two screening tasks tested their auditory discrimination of case morphology and their perception and comprehension of subject-verb agreement. Results Children with CIs who performed well on the screening tests still showed more difficulty on the comprehension of object questions than children with NH, whereas they comprehended subject questions and passive questions equally well as children with NH. There was large interindividual variability within the CI group. The gaze patterns of children with NH showed reanalysis effects for object questions disambiguated later in the sentence by verb agreement, but not for object questions disambiguated by case at the first noun phrase. The gaze patterns of children with CIs showed reanalysis effects even for object questions disambiguated at the first noun phrase. Conclusions Even when children with CIs perceive case and subject-verb agreement, their ability to use these cues for offline comprehension and online processing still lags behind normal development, which is reflected in lower performance rates and longer processing times. Individual variability within the CI group can partly be explained by working memory and hearing age. Supplemental Material https://doi.org/10.23641/asha.7728731.

The Production of Question Intonation by Young Adult Cochlear Implant Users: Does Age at Implantation Matter?

Purpose The purpose of this observational study was to investigate the properties of sentence-final prosody in yes/no questions produced by cochlear implant (CI) users in order to determine whether and how the age at CI implantation impacts CI users' production of question intonation later in life. Method We acoustically analyzed recordings from 46 young adult CI users and 10 young adults with normal hearing who read yes/no questions. Of the 46 CI users, 20 had received their CI before the age of 4.0 years (early implantation group), 15 between ages 4.0 and 8.11 years (midimplantation group), and 11 at the age of 9.0 years or later (late implantation group). We assessed the prosodic properties of the produced questions for each implantation group and the normal hearing comparison group (a) by measuring the sentence-final rise in fundamental frequency, (b) by labeling the question-final intonation contour using the Tones and Breaks Index ( Beckman & Ayers, 1994 ; Silverman, Beckman, et al., 1992 ; Veilleux, Shattuck-Hufnagel, & Brugos, 2006 ), and (c) by assessing phrase-final lengthening. Results The fundamental frequency rises produced by all CI users exhibited a smaller magnitude than those produced by the normal hearing comparison group, although the difference between early implanted CI users and the normal hearing group did not reach statistical significance. Early implanted CI users were more comparable in their use of question-final intonation contours to the individuals with typical hearing than to those users with CI implanted later in life. All CI users exhibited significantly less phrase-final lengthening than the normal hearing comparison group, regardless of age at CI implantation. Conclusion The results of this investigation of question intonation produced by CI users suggest that those CI users who were implanted with CI earlier in life produce yes/no question intonation in a manner that is more similar to, albeit not the same as, individuals with normal hearing when compared to the productions of those users with CI implanted after 4.0 years of age.

Functional near-infrared spectroscopy as a tool for assessing speech and spoken language processing in pediatric and adult cochlear implant users

Much of what is known about the course of auditory learning in following cochlear implantation is based on behavioral indicators that users are able to perceive sound. Both prelingually deafened children and postlingually deafened adults who receive cochlear implants display highly variable speech and language processing outcomes, although the basis for this is poorly understood. To date, measuring neural activity within the auditory cortex of implant recipients of all ages has been challenging, primarily because the use of traditional neuroimaging techniques is limited by the implant itself. Functional near-infrared spectroscopy (fNIRS) is an imaging technology that works with implant users of all ages because it is non-invasive, compatible with implant devices, and not subject to electrical artifacts. Thus, fNIRS can provide insight into processing factors that contribute to variations in spoken language outcomes in implant users, both children and adults. There are important considerations to be made when using fNIRS, particularly with children, to maximize the signal-to-noise ratio and to best identify and interpret cortical responses. This review considers these issues, recent data, and future directions for using fNIRS as a tool to understand spoken language processing in children and adults who hear through a cochlear implant.

Auditory disorders and future therapies with delivery systems

Auditory function takes a major part in human life. While sensorineural hearing loss is related with many factors including genetic disorders, age and noise, the clear causes are not well understood. Even more, the currently available treatments with drugs cause side effects, which thus are considered suboptimal. Here, we communicate the delivery systems with biomaterials that can be possible therapeutic options to restore hearing and vestibular functions. We introduce briefly the various pathological factors related with hearing loss and the limitation of current therapies, detail the recent studies on delivery systems including nanoparticles and hydrogels and discuss future clinical availability.

Executive Function in Deaf Children: Auditory Access and Language Access

Purpose

Deaf children are frequently reported to be at risk for difficulties in executive function (EF); however, the literature is divided over whether these difficulties are the result of deafness itself or of delays/deficits in language that often co-occur with deafness. The purpose of this study is to discriminate these hypotheses by assessing EF in populations where the 2 accounts make contrasting predictions.

Method

We use a between-groups design involving 116 children, ages 5-12 years, across 3 groups: (a) participants with normal hearing (n = 45), (b) deaf native signers who had access to American Sign Language from birth (n = 45), and (c) oral cochlear implant users who did not have full access to language prior to cochlear implantation (n = 26). Measures include both parent report and performance-based assessments of EF.

Results

Parent report results suggest that early access to language has a stronger impact on EF than early access to sound. Performance-based results trended in a similar direction, but no between-group differences were significant.

Conclusions

These results indicate that healthy EF skills do not require audition and therefore that difficulties in this domain do not result primarily from a lack of auditory experience. Instead, results are consistent with the hypothesis that language proficiency, whether in sign or speech, is crucial for the development of healthy EF. Further research is needed to test whether sign language proficiency also confers benefits to deaf children from hearing families.

Using aided cortical assessment as an objective tool to evaluate cochlear implant fitting in users with single-sided deafness

OBJECTIVES

To assess the use of cortical auditory evoked potentials (CAEPs) to verify, and if necessary, optimize the cochlear implant (CI) fitting of adult CI users with postlingual single-sided deafness (SSD).

METHODS

Sound field cortical responses to the speech tokens /m/, /g/, /t/, and /s/ were recorded from input to the CI while the normal hearing ear was masked. Responses were evaluated by visual inspection and classified as presence or absence of the CAEPs components P1, N1, P2. In case of an absence fitting was adjusted accordingly. After fitting, subjects were asked to use their new setting for 2-3 weeks for acclimatization purposes and then return for retesting. At retesting, new CAEP recordings were performed to objectively ensure that the new fitting maps effectively activated the auditory cortex.

RESULTS

In 14/19 subjects, as per visual inspection, clear CAEPs were recorded by each speech token and were, therefore, not refit. In the other 5 subjects, CAEPs could not be evoked for at least one speech token. The fitting maps in these subjects were adjusted until clear CAEPs were evoked for all 4 speech tokens.

CONCLUSIONS

CAEP can be used to quickly and objectively verify the suitability of CI fitting in experienced adult CI users with SSD. If used in the early post-implantation stage, this method could help CI users derive greater benefit for CI use and, therefore, be more committed to auditory training.

An automated A-value measurement tool for accurate cochlear duct length estimation

BACKGROUND

There has been renewed interest in the cochlear duct length (CDL) for preoperative cochlear implant electrode selection and postoperative generation of patient-specific frequency maps. The CDL can be estimated by measuring the A-value, which is defined as the length between the round window and the furthest point on the basal turn. Unfortunately, there is significant intra- and inter-observer variability when these measurements are made clinically. The objective of this study was to develop an automated A-value measurement algorithm to improve accuracy and eliminate observer variability.

METHOD

Clinical and micro-CT images of 20 cadaveric cochleae specimens were acquired. The micro-CT of one sample was chosen as the atlas, and A-value fiducials were placed onto that image. Image registration (rigid affine and non-rigid B-spline) was applied between the atlas and the 19 remaining clinical CT images. The registration transform was applied to the A-value fiducials, and the A-value was then automatically calculated for each specimen. High resolution micro-CT images of the same 19 specimens were used to measure the gold standard A-values for comparison against the manual and automated methods.

RESULTS

The registration algorithm had excellent qualitative overlap between the atlas and target images. The automated method eliminated the observer variability and the systematic underestimation by experts. Manual measurement of the A-value on clinical CT had a mean error of 9.5 ± 4.3% compared to micro-CT, and this improved to an error of 2.7 ± 2.1% using the automated algorithm. Both the automated and manual methods correlated significantly with the gold standard micro-CT A-values (r = 0.70, p < 0.01 and r = 0.69, p < 0.01, respectively).

CONCLUSION

An automated A-value measurement tool using atlas-based registration methods was successfully developed and validated. The automated method eliminated the observer variability and improved accuracy as compared to manual measurements by experts. This open-source tool has the potential to benefit cochlear implant recipients in the future.

Acoustic Cue Weighting by Adults with Cochlear Implants: A Mismatch Negativity Study

OBJECTIVES

Formant rise time (FRT) and amplitude rise time (ART) are acoustic cues that inform phonetic identity. FRT represents the rate of transition of the formant(s) to a steady state, while ART represents the rate at which the sound reaches its peak amplitude. Normal-hearing (NH) native English speakers weight FRT more than ART during the perceptual labeling of the /ba/-/wa/ contrast. This weighting strategy is reflected neurophysiologically in the magnitude of the mismatch negativity (MMN)-MMN is larger during the FRT than the ART distinction. The present study examined the neurophysiological basis of acoustic cue weighting in adult cochlear implant (CI) listeners using the MMN design. It was hypothesized that individuals with CIs who weight ART more in behavioral labeling (ART users) would show larger MMNs during the ART than the FRT contrast, and the opposite would be seen for FRT users.

DESIGN

Electroencephalography was recorded while 20 adults with CIs listened passively to combinations of 3 synthetic speech stimuli: a /ba/ with /ba/-like FRT and ART; a /wa/ with /wa/-like FRT and ART; and a /ba/ stimulus with /ba/-like FRT and /wa/-like ART. The MMN response was elicited during the FRT contrast by having participants passively listen to a train of /wa/ stimuli interrupted occasionally by /ba/ stimuli, and vice versa. For the ART contrast, the same procedure was implemented using the /ba/ and /ba/ stimuli.

RESULTS

Both ART and FRT users with CIs elicited MMNs that were equal in magnitudes during FRT and ART contrasts, with the exception that FRT users exhibited MMNs for ART and FRT contrasts that were temporally segregated. That is, their MMNs occurred significantly earlier during the ART contrast (~100 msec following sound onset) than during the FRT contrast (~200 msec). In contrast, the MMNs for ART users of both contrasts occurred later and were not significantly separable in time (~230 msec). Interestingly, this temporal segregation observed in FRT users is consistent with the MMN behavior in NH listeners.

CONCLUSIONS

Results suggest that listeners with CIs who learn to classify phonemes based on formant dynamics, consistent with NH listeners, develop a strategy similar to NH listeners, in which the organization of the amplitude and spectral representations of phonemes in auditory memory are temporally segregated.

Interfacing with the nervous system: a review of current bioelectric technologies

The aim of this study is to discuss the state of the art with regard to established or promising bioelectric therapies meant to alter or control neurologic function. We present recent reports on bioelectric technologies that interface with the nervous system at three potential sites-(1) the end organ, (2) the peripheral nervous system, and (3) the central nervous system-while exploring practical and clinical considerations. A literature search was executed on PubMed, IEEE, and Web of Science databases. A review of the current literature was conducted to examine functional and histomorphological effects of neuroprosthetic interfaces with a focus on end-organ, peripheral, and central nervous system interfaces. Innovations in bioelectric technologies are providing increasing selectivity in stimulating distinct nerve fiber populations in order to activate discrete muscles. Significant advances in electrode array design focus on increasing selectivity, stability, and functionality of implantable neuroprosthetics. The application of neuroprosthetics to paretic nerves or even directly stimulating or recording from the central nervous system holds great potential in advancing the field of nerve and tissue bioelectric engineering and contributing to clinical care. Although current physiotherapeutic and surgical treatments seek to restore function, structure, or comfort, they bear significant limitations in enabling cosmetic or functional recovery. Instead, the introduction of bioelectric technology may play a role in the restoration of function in patients with neurologic deficits.

Multisensory emotion perception in congenitally, early, and late deaf CI users

Emotions are commonly recognized by combining auditory and visual signals (i.e., vocal and facial expressions). Yet it is unknown whether the ability to link emotional signals across modalities depends on early experience with audio-visual stimuli. In the present study, we investigated the role of auditory experience at different stages of development for auditory, visual, and multisensory emotion recognition abilities in three groups of adolescent and adult cochlear implant (CI) users. CI users had a different deafness onset and were compared to three groups of age- and gender-matched hearing control participants. We hypothesized that congenitally deaf (CD) but not early deaf (ED) and late deaf (LD) CI users would show reduced multisensory interactions and a higher visual dominance in emotion perception than their hearing controls. The CD (n = 7), ED (deafness onset: <3 years of age; n = 7), and LD (deafness onset: >3 years; n = 13) CI users and the control participants performed an emotion recognition task with auditory, visual, and audio-visual emotionally congruent and incongruent nonsense speech stimuli. In different blocks, participants judged either the vocal (Voice task) or the facial expressions (Face task). In the Voice task, all three CI groups performed overall less efficiently than their respective controls and experienced higher interference from incongruent facial information. Furthermore, the ED CI users benefitted more than their controls from congruent faces and the CD CI users showed an analogous trend. In the Face task, recognition efficiency of the CI users and controls did not differ. Our results suggest that CI users acquire multisensory interactions to some degree, even after congenital deafness. When judging affective prosody they appear impaired and more strongly biased by concurrent facial information than typically hearing individuals. We speculate that limitations inherent to the CI contribute to these group differences.

Neural decoding of attentional selection in multi-speaker environments without access to clean sources

OBJECTIVE

People who suffer from hearing impairments can find it difficult to follow a conversation in a multi-speaker environment. Current hearing aids can suppress background noise; however, there is little that can be done to help a user attend to a single conversation amongst many without knowing which speaker the user is attending to. Cognitively controlled hearing aids that use auditory attention decoding (AAD) methods are the next step in offering help. Translating the successes in AAD research to real-world applications poses a number of challenges, including the lack of access to the clean sound sources in the environment with which to compare with the neural signals. We propose a novel framework that combines single-channel speech separation algorithms with AAD.

APPROACH

We present an end-to-end system that (1) receives a single audio channel containing a mixture of speakers that is heard by a listener along with the listener's neural signals, (2) automatically separates the individual speakers in the mixture, (3) determines the attended speaker, and (4) amplifies the attended speaker's voice to assist the listener.

MAIN RESULTS

Using invasive electrophysiology recordings, we identified the regions of the auditory cortex that contribute to AAD. Given appropriate electrode locations, our system is able to decode the attention of subjects and amplify the attended speaker using only the mixed audio. Our quality assessment of the modified audio demonstrates a significant improvement in both subjective and objective speech quality measures.

SIGNIFICANCE

Our novel framework for AAD bridges the gap between the most recent advancements in speech processing technologies and speech prosthesis research and moves us closer to the development of cognitively controlled hearable devices for the hearing impaired.

Waiting for lexical access: Cochlear implants or severely degraded input lead listeners to process speech less incrementally

Spoken language unfolds over time. Consequently, there are brief periods of ambiguity, when incomplete input can match many possible words. Typical listeners solve this problem by immediately activating multiple candidates which compete for recognition. In two experiments using the visual world paradigm, we examined real-time lexical competition in prelingually deaf cochlear implant (CI) users, and normal hearing (NH) adults listening to severely degraded speech. In Experiment 1, adolescent CI users and NH controls matched spoken words to arrays of pictures including pictures of the target word and phonological competitors. Eye-movements to each referent were monitored asa measure of how strongly that candidate was considered over time. Relative to NH controls, CI users showed a large delay in fixating any object, less competition from onset competitors (e.g., sandwich after hearing sandal), and increased competition from rhyme competitors (e.g., candle after hearing sandal). Experiment 2 observed the same pattern with NH listeners hearing highly degraded speech. These studies suggests that in contrast to all prior studies of word recognition in typical listeners, listeners recognizing words in severely degraded conditions can exhibit a substantively different pattern of dynamics, waiting to begin lexical access until substantial information has accumulated.

Early Postimplant Speech Perception and Language Skills Predict Long-Term Language and Neurocognitive Outcomes Following Pediatric Cochlear Implantation

Purpose

We sought to determine whether speech perception and language skills measured early after cochlear implantation in children who are deaf, and early postimplant growth in speech perception and language skills, predict long-term speech perception, language, and neurocognitive outcomes.

Method

Thirty-six long-term users of cochlear implants, implanted at an average age of 3.4 years, completed measures of speech perception, language, and executive functioning an average of 14.4 years postimplantation. Speech perception and language skills measured in the 1st and 2nd years postimplantation and open-set word recognition measured in the 3rd and 4th years postimplantation were obtained from a research database in order to assess predictive relations with long-term outcomes.

Results

Speech perception and language skills at 6 and 18 months postimplantation were correlated with long-term outcomes for language, verbal working memory, and parent-reported executive functioning. Open-set word recognition was correlated with early speech perception and language skills and long-term speech perception and language outcomes. Hierarchical regressions showed that early speech perception and language skills at 6 months postimplantation and growth in these skills from 6 to 18 months both accounted for substantial variance in long-term outcomes for language and verbal working memory that was not explained by conventional demographic and hearing factors.

Conclusion

Speech perception and language skills measured very early postimplantation, and early postimplant growth in speech perception and language, may be clinically relevant markers of long-term language and neurocognitive outcomes in users of cochlear implants.

Supplemental materials

https://doi.org/10.23641/asha.5216200.

Profiling morpho-syntactical development of cochlear implanted children with TR-LARSP

This research aims to describe the grammatical development of Turkish-speaking children with cochlear implants (CI) using the Turkish adaptation of the Language Assessment and Remediation Profile (LARSP). The study was conducted on a total of 15 children with CIs aged 43-87 months with 22-45 months of hearing age. A total of 750 utterances were elicited from the CI group's recorded speech samples and analysed using the methodology of Turkish-Language Assessment and Remediation Profile (TR-LARSP). A cross-sectional descriptive model is used in the study. The results show that there is a significant difference in the acquisition of grammatical structures in children with CIs as compared to typically developing (TD) age-matched children in Turkish. In conclusion, this study suggests that after the implantation of these children, the speech therapist should consider the acquisition time of morpho-syntactical structures before making a language-based therapy plan.