Biomarkers of auditory cortical plasticity and development of binaural pathways in children with unilateral hearing loss using a hearing aid.

Congenital or early-onset unilateral hearing loss (UHL) can disrupt the normal development of the auditory system. In extreme cases of UHL (i.e., single sided deafness), consistent cochlear implant use during sensitive periods resulted in cortical reorganization that partially reversed the detrimental effects of unilateral sensory deprivation. There is a gap in knowledge, however, regarding cortical plasticity i.e. the brain's capacity to adapt, reorganize, and develop binaural pathways in milder degrees of UHL rehabilitated by a hearing aid (HA). The current study was set to investigate early-stage cortical processing and electrophysiological manifestations of binaural processing by means of cortical auditory evoked potentials (CAEPs) to speech sounds, in children with moderate to severe-to-profound UHL using a HA. Fourteen children with UHL (CHwUHL), 6-14 years old consistently using a HA for 3.5 (±2.3) years participated in the study. CAEPs were elicited to the speech sounds /m/, /g/, and /t/ in three listening conditions: monaural [Normal hearing (NH), HA], and bilateral [BI (NH + HA)]. Results indicated age-appropriate CAEP morphology in the NH and BI listening conditions in all children. In the HA listening condition: (1) CAEPs showed similar morphology to that found in the NH listening condition, however, the mature morphology observed in older children in the NH listening condition was not evident; (2) P1 was elicited in all but two children with severe-to-profound hearing loss, to at least one speech stimuli, indicating effective audibility; (3) A significant mismatch in timing and synchrony between the NH and HA ear was found; (4) P1 was sensitive to the acoustic features of the eliciting stimulus and to the amplification characteristics of the HA. Finally, a cortical binaural interaction component (BIC) was derived in most children. In conclusion, the current study provides first-time evidence for cortical plasticity and partial reversal of the detrimental effects of moderate to severe-to-profound UHL rehabilitated by a HA. The derivation of a cortical biomarker of binaural processing implies that functional binaural pathways can develop when sufficient auditory input is provided to the affected ear. CAEPs may thus serve as a clinical tool for assessing, monitoring, and managing CHwUHL using a HA.

A Perspective on Auditory Wellness: What It Is, Why It Is Important, and How It Can Be Managed.

During the last decade, there has been a move towards consumer-centric hearing healthcare. This is a direct result of technological advancements (e.g., merger of consumer grade hearing aids with consumer grade earphones creating a wide range of hearing devices) as well as policy changes (e.g., the U.S. Food and Drug Administration creating a new over-the-counter [OTC] hearing aid category). In addition to various direct-to-consumer (DTC) hearing devices available on the market, there are also several validated tools for the self-assessment of auditory function and the detection of ear disease, as well as tools for education about hearing loss, hearing devices, and communication strategies. Further, all can be made easily available to a wide range of people. This perspective provides a framework and identifies tools to improve and maintain optimal auditory wellness across the adult life course. A broadly available and accessible set of tools that can be made available on a digital platform to aid adults in the assessment and as needed, the improvement, of auditory wellness is discussed.

Factors associated with the anxiety score of deaf and hearing mothers. / Fatores associados ao escore de ansiedade de mães surdas e ouvintes.

PURPOSE: To associate maternal anxiety with sociodemographic factors, breastfeeding practices, oral habits, and the child's entry into daycare among deaf and hearing (non-deaf) mothers. METHODS: This retrospective comparative cross-sectional study included 116 mothers (29 deaf and 87 hearing) of children aged between two and five years. Deaf mothers belonged to a reference center in the city, while hearing mothers were contacted in public daycares where their children were enrolled. Mothers underwent interviews covering socio-economic factors and child development-related aspects. Additionally, they completed the Brazilian Beck Anxiety Inventory, adapted for both deaf and hearing individuals, serving as instruments to assess anxiety. The Kolmogorov-Smirnov normality test, Kruskal Wallis test, Mann-Whitney test, and Poisson Regression were employed for statistical analyses (p<0.05). RESULTS: Deaf mothers exhibited anxiety scores one and a half times higher than hearing mothers. Moreover, mothers of children with thumb-sucking habits showed higher anxiety scores, while mothers whose children started attending daycare as infants demonstrated lower anxiety scores compared to mothers of children without such habits and who did not attend daycare. CONCLUSION: Deaf mothers displayed higher anxiety levels when compared to hearing mothers. Children's behaviors, such as thumb-sucking habits, and early enrollment in daycare during the first year of life influenced maternal anxiety.

OBJETIVO: Associar a ansiedade materna aos fatores sociodemográficos, pratica de aleitamento, hábitos bucais e ingresso da criança em creche entre mulheres surdas e ouvintes. MÉTODO: Participaram deste estudo transversal retrospectivo comparativo, 116 mães (29 surdas e 87 ouvintes) de crianças na faixa etária entre dois e cinco anos. As mães surdas pertenciam a um centro de referência da cidade e as mães ouvintes foram contatadas em creches públicas, onde seus filhos estavam matriculados. As mães foram submetidas a entrevista sobre fatores socioeconômicos e relacionados ao desenvolvimento dos filhos, além de realizarem o preenchimento do Inventário Brasileiro de Ansiedade de Beck, nas versões para surdos e ouvintes, que foram instrumentos usados para avaliar a ansiedade. O teste de normalidade de Kolmogorov-Smirnov, os testes de Kruskal Wallis, Mann-Whitney e Regressão de Poisson foram utilizados para análises estatísticas (p <0,05). RESULTADOS: Mães surdas apresentaram escore de ansiedade uma vez e meia maior que mães ouvintes. Além disso, mães de crianças com hábito de sucção de dedo apresentaram maior escore de ansiedade e mães cujos filhos começaram a frequentar a creche ainda bebês apresentaram menor escore de ansiedade, quando comparados a crianças sem o hábito e que não frequentavam a creche. CONCLUSÃO: Mães surdas apresentaram maior ansiedade quando comparadas às ouvintes. Comportamento dos filhos com hábitos de sucção de dedo e o ingresso em creches no primeiro ano de vida influenciaram a ansiedade materna.

A Step Toward Precision Audiology: Individual Differences and Characteristic Profiles From Auditory Perceptual and Cognitive Abilities.

Older adults with normal hearing or with age-related hearing loss face challenges when listening to speech in noisy environments. To better serve individuals with communication difficulties, precision diagnostics are needed to characterize individuals' auditory perceptual and cognitive abilities beyond pure tone thresholds. These abilities can be heterogenous across individuals within the same population. The goal of the present study is to consider the suprathreshold variability and develop characteristic profiles for older adults with normal hearing (ONH) and with hearing loss (OHL). Auditory perceptual and cognitive abilities were tested on ONH (n = 20) and OHL (n = 20) on an abbreviated test battery using portable automated rapid testing. Using cluster analyses, three main profiles were revealed for each group, showing differences in auditory perceptual and cognitive abilities despite similar audiometric thresholds. Analysis of variance showed that ONH profiles differed in spatial release from masking, speech-in-babble testing, cognition, tone-in-noise, and binaural temporal processing abilities. The OHL profiles differed in spatial release from masking, speech-in-babble testing, cognition, and tolerance to background noise performance. Correlation analyses showed significant relationships between auditory and cognitive abilities in both groups. This study showed that auditory perceptual and cognitive deficits can be present to varying degrees in the presence of audiometrically normal hearing and among listeners with similar degrees of hearing loss. The results of this study inform the need for taking individual differences into consideration and developing targeted intervention options beyond pure tone thresholds and speech testing.

Teletherapy to address language disparities in deaf and hard-of-hearing children: study protocol for an inclusive multicentre clinical trial.

INTRODUCTION: Children who are deaf or hard-of-hearing (DHH) are at risk for speech and language delay. Language outcomes are worse in DHH children from lower socioeconomic backgrounds, due in part to disparities in access to specialised speech-language therapy. Teletherapy may help improve access to this specialised care and close this language gap. Inclusion of diverse DHH children in prospective randomised clinical trials has been challenging but is necessary to address disparities and pursue hearing health equity. Stakeholder input regarding decisions on study design elements, including comparator groups, masking, assessments and compensation, is necessary to design inclusive studies. We have designed an inclusive, equitable comparativeness effectiveness trial to address disparities in paediatric hearing health. The specific aims of the study are to determine the effect of access to and utilisation of speech-language teletherapy in addressing language disparities in low-income children who are DHH. METHODS AND ANALYSIS: After stakeholder input and pilot data collection, we designed a randomised clinical trial and concurrent longitudinal cohort trial to be conducted at four tertiary children's hospitals in the USA. Participants will include 210 DHH children aged 0-27 months. 140 of these children will be from lower income households, who will be randomised 1:1 to receive usual care versus usual care plus access to supplemental speech-language teletherapy. 70 children from higher income households will be simultaneously recruited as a comparison cohort. Primary outcome measure will be the Preschool Language Scales Auditory Comprehension subscale standard score, with additional speech, language, hearing and quality of life validated measures as secondary outcomes. ETHICS AND DISSEMINATION: This study was approved by the Institutional Review Boards of the participating sites: the University of California, San Francisco (19-28356), Rady Children's Hospital (804651) and Seattle Children's Hospital (STUDY00003750). Parents of enrolled children will provide written informed consent for their child's participation. Professional and parent stakeholder groups that have been involved throughout the study design will facilitate dissemination and implementation of study findings via publication and through national and regional organisations. TRIAL REGISTRATION NUMBER: NCT04928209.

Prevalence and Characteristics of Veterans with Severe Hearing Loss: A Descriptive Study.

Hearing loss is common among Veterans, and extensive hearing care resources are prioritized within the Veterans Administration (VA). Severe hearing loss poses unique communication challenges with speech understanding that may not be overcome with amplification. We analyzed data from the VA Audiometric Repository between 2005 and 2017 and the relationship between hearing loss severity with speech recognition scores. We hypothesized that a significant subset of Veterans with severe or worse hearing loss would have poor unaided speech perception outcomes even with adequate audibility. Sociodemographic characteristics and comorbidities were compiled using electronic medical records as was self-report measures of hearing disability. We identified a cohort of 137,500 unique Veterans with 232,789 audiograms demonstrating bilateral severe or worse hearing loss (four-frequency PTA > 70 dB HL). The median (IQR; range) age of Veterans at their first audiogram with severe or worse hearing loss was 81 years (74 to 87; 21-90+), and a majority were male (136,087 [99%]) and non-Hispanic white (107,798 [78.4%]). Among those with bilateral severe or worse hearing loss, 41,901 (30.5%) also had poor speech recognition scores (<50% words), with greater hearing loss severity correlating with worse speech perception. We observed variability in speech perception abilities in those with moderate-severe and greater levels of hearing loss who may derive limited benefit from amplification. Veterans with communication challenges may warrant alternative approaches and treatment strategies such as cochlear implants to support communication needs.

The Impact of Hearing Aids on Listening Effort and Listening-Related Fatigue - Investigations in a Virtual Realistic Listening Environment.

Participation in complex listening situations such as group conversations in noisy environments sets high demands on the auditory system and on cognitive processing. Reports of hearing-impaired people indicate that strenuous listening situations occurring throughout the day lead to feelings of fatigue at the end of the day. The aim of the present study was to develop a suitable test sequence to evoke and measure listening effort (LE) and listening-related fatigue (LRF), and, to evaluate the influence of hearing aid use on both dimensions in mild to moderately hearing-impaired participants. The chosen approach aims to reconstruct a representative acoustic day (Time Compressed Acoustic Day [TCAD]) by means of an eight-part hearing-test sequence with a total duration of approximately 2½ h. For this purpose, the hearing test sequence combined four different listening tasks with five different acoustic scenarios and was presented to the 20 test subjects using virtual acoustics in an open field measurement in aided and unaided conditions. Besides subjective ratings of LE and LRF, behavioral measures (response accuracy, reaction times), and an attention test (d2-R) were performed prior to and after the TCAD. Furthermore, stress hormones were evaluated by taking salivary samples. Subjective ratings of LRF increased throughout the test sequence. This effect was observed to be higher when testing unaided. In three of the eight listening tests, the aided condition led to significantly faster reaction times/response accuracies than in the unaided condition. In the d2-R test, an interaction in processing speed between time (pre- vs. post-TCAD) and provision (unaided vs. aided) was found suggesting an influence of hearing aid provision on LRF. A comparison of the averaged subjective ratings at the beginning and end of the TCAD shows a significant increase in LRF for both conditions. At the end of the TCAD, subjective fatigue was significantly lower when wearing hearing aids. The analysis of stress hormones did not reveal significant effects.

Improving communication and promoting social inclusion for hearing-impaired users: Usability evaluation and design recommendations for assistive mobile applications.

This study examines the usability of communication-assistive applications for hearing-impaired users, with a focus on enhancing user experience and promoting social inclusion. Although such applications have been developed and evaluated previously, interface designs that consider the intimacy needs of hearing-impaired users remain under-explored. We performed a comprehensive usability evaluation employing a mixed-method approach, which involved hearing-impaired individuals as well as field experts. The findings revealed areas for improvement in the design, validated the feasibility of implementing these applications, and emphasized the importance of incorporating the unique needs and preferences of hearing-impaired users. Furthermore, this paper discusses the importance of introducing guidelines and evaluation scales for the "Design for Emotion and Life Knowledge" levels to facilitate smooth and effective human-computer interactions. Such measures will promote the development of intelligent assistive technologies that reflect the qualitative needs of people with disabilities and contribute to social rights for hearing-impaired users. With the growing demands of artificial-intelligence-powered assistive technologies, the inclusion of individuals with disabilities in the design and research process is anticipated to increase. In future, studies should be conducted to blend the culturally shared experiences and emotional bonds expressed by users (having mild-to-severe hearing impairment) with the design and development process of assistive devices or services.

Attenuation and distortion components of age-related hearing loss: Contributions to recognizing temporal-envelope filtered speech in modulated noise.

Older adults with hearing loss may experience difficulty recognizing speech in noise due to factors related to attenuation (e.g., reduced audibility and sensation levels, SLs) and distortion (e.g., reduced temporal fine structure, TFS, processing). Furthermore, speech recognition may improve when the amplitude modulation spectrum of the speech and masker are non-overlapping. The current study investigated this by filtering the amplitude modulation spectrum into different modulation rates for speech and speech-modulated noise. The modulation depth of the noise was manipulated to vary the SL of speech glimpses. Younger adults with normal hearing and older adults with normal or impaired hearing listened to natural speech or speech vocoded to degrade TFS cues. Control groups of younger adults were tested on all conditions with spectrally shaped speech and threshold matching noise, which reduced audibility to match that of the older hearing-impaired group. All groups benefitted from increased masker modulation depth and preservation of syllabic-rate speech modulations. Older adults with hearing loss had reduced speech recognition across all conditions. This was explained by factors related to attenuation, due to reduced SLs, and distortion, due to reduced TFS processing, which resulted in poorer auditory processing of speech cues during the dips of the masker.

The Reading of Deaf Arabic Children in Israel.

Studies on the reading acquisition of deaf children investigate the similarities and differences in the reading process between these readers and typical hearing readers. There is no consensus on the nature of the reading process among deaf readers, whether they use the same reading processing strategies as typical readers or depend on other strategies to close the gap. The present study aimed to test the types of strategies used to process written words by deaf Arabic readers with prelingual deafness, compared to their hearing peers, and to test the effectiveness of deaf readers' use of these strategies. Three experimental paradigms were tested. The findings indicated that deaf Arabic readers rely on essentially similar processing strategies to those used by hearing readers. However, deaf Arabic readers employ these strategies with significantly less effectiveness. The results are discussed in light of international data.

How to Improve Grit Among Deaf or Hard of Hearing Students: The Effect of Thinking Style.

The researchers examined the associations between thinking styles and grit. A cross-sectional design was adopted, with two weeks of data collection. The Thinking Styles Inventory-Revised II and the Grit Scale were administered to 365 signing deaf or hard-of-hearing (DHH) Arts and Design students and 443 hearing university students in mainland China. CFA, MANOVA, hierarchical multiple regression analyses, and a multi-group analysis were executed for data analysis. DHH and hearing students with Type I styles (i.e., more creativity-generating, less structured, and cognitively more complex) had higher grit levels, with large effect sizes for the identified relationships. There were no differences in the relations for either group. The associations between thinking styles and grit may protect against psychological pressure and rehabilitation problems and enable university/school administrators, counselors, social workers, teachers, parents, and students to enhance the grit of students who are deaf or hard of hearing.

"Where I Didn't Have to Hear Anything, and I Could Just Run": The Lived Sport Experiences of Deaf or Hard of Hearing Collegiate Athletes.

Accessible and inclusive participation in sport can provide significant physical, psychological, and social benefits to Deaf or hard of hearing (D/HH) athletes. To understand how to facilitate these benefits, the researchers explored the lived physical education and sport experiences of D/HH collegiate athletes. Six athletes representing six sports were recruited and interviewed. Utilizing an interpretative phenomenological analysis approach to guide data collection, analysis, and interpretation, the researchers found five major themes: Self-Advocating for Awareness, Finding Meaningful Conversations, Overcoming Challenges, Seeking Community Connection, and Escaping Through Physical Activity. These themes illustrate the influence of accessibility and inclusion on the participants' sport experiences as well as the impact of the disability awareness of their coaches and peers. D/HH athletes and their coaches and teammates should work to overcome barriers to accessibility and inclusion to ensure the maximum benefit of being on a college sports team.

Mental Health, Parenting Stress, and Parenting Practices of Parents of Deaf or Hard of Hearing Children During the Pandemic.

The authors investigated parent mental health during the COVID-19 pandemic and its association with parenting behaviors of parents of children who are deaf or hard of hearing. An electronic survey was distributed to parents (N = 103). The results showed that they were experiencing elevated anxiety, depression, and symptoms of post-traumatic stress disorder. A combined model demonstrated that parental distress was significantly associated with depression and with parental reports of symptoms indicating significantly higher distress. Parental distress was also significantly associated with parenting strategies: Parents who endorsed positive strategies reported significantly lower levels of distress, while parents who endorsed negative strategies reporting significantly higher levels. It was found that screening protocols to identify parents in need of support are crucial, particularly among the parent population considered in the present study. Additionally, access to mental health services and evidence-based positive parenting programs is essential.

Neurocognitive outcomes in young adults with cochlear implants: The role of early language access and crossmodal plasticity.

Many children with profound hearing loss have received cochlear implants (CI) to help restore some sense of hearing. There is, however, limited research on long-term neurocognitive outcomes in young adults who have grown up hearing through a CI. This study compared the cognitive outcomes of early-implanted (n = 20) and late-implanted (n = 21) young adult CI users, and typically hearing (TH) controls (n=56), all of whom were enrolled in college. Cognitive fluidity, nonverbal intelligence, and American Sign Language (ASL) comprehension were assessed, revealing no significant differences in cognition and nonverbal intelligence between the early and late-implanted groups. However, there was a difference in ASL comprehension, with the late-implanted group having significantly higher ASL comprehension. Although young adult CI users showed significantly lower scores in a working memory and processing speed task than TH age-matched controls, there were no significant differences in tasks involving executive function shifting, inhibitory control, and episodic memory between young adult CI and young adult TH participants. In an exploratory analysis of a subset of CI participants (n = 17) in whom we were able to examine crossmodal plasticity, we saw greater evidence of crossmodal recruitment from the visual system in late-implanted compared with early-implanted CI young adults. However, cortical visual evoked potential latency biomarkers of crossmodal plasticity were not correlated with cognitive measures or ASL comprehension. The results suggest that in the late-implanted CI users, early access to sign language may have served as a scaffold for appropriate cognitive development, while in the early-implanted group early access to oral language benefited cognitive development. Furthermore, our results suggest that the persistence of crossmodal neuroplasticity into adulthood does not necessarily impact cognitive development. In conclusion, early access to language - spoken or signed - may be important for cognitive development, with no observable effect of crossmodal plasticity on cognitive outcomes.

The temporal mismatch across listening sides affects cortical auditory evoked responses in normal hearing listeners and cochlear implant users with contralateral acoustic hearing.

Combining a cochlear implant with contralateral acoustic hearing typically enhances speech understanding, although this improvement varies among CI users and can lead to an interference effect. This variability may be associated with the effectiveness of the integration between electric and acoustic stimulation, which might be affected by the temporal mismatch between the two listening sides. Finding methods to compensate for the temporal mismatch might contribute to the optimal adjustment of bimodal devices and to improve hearing in CI users with contralateral acoustic hearing. The current study investigates cortical auditory evoked potentials (CAEPs) in normal hearing listeners (NH) and CI users with contralateral acoustic hearing. In NH, the amplitude of the N1 peak and the maximum phase locking value (PLV) were analyzed under monaural, binaural, and binaural temporally mismatched conditions. In CI users, CAEPs were measured when listening with CI only (CIS_only), acoustically only (AS_only) and with both sides together (CIS+AS). When listening with CIS+AS, various interaural delays were introduced between the electric and acoustic stimuli. In NH listeners, interaural temporal mismatch resulted in decreased N1 amplitude and PLV. Moreover, PLV is suggested as a more sensitive measure to investigate the integration of information between the two listening sides. CI users showed varied N1 latencies between the AS_only and CIS_only listening conditions, with increased N1 amplitude when the temporal mismatch was compensated. A tendency towards increased PLV was also observed, however, to a lesser extent than in NH listeners, suggesting a limited integration between electric and acoustic stimulation. This work highlights the potential of CAEPs measurement to investigate cortical processing of the information between two listening sides in NH and bimodal CI users.

Adaptive Strategies of Single-Sided Deaf Cochlear-Implant Users Revealed Through Resting State Activity: an Auditory PET Brain Imaging Study.

Brain plasticity refers to the brain's ability to reorganize its structure or function in response to experiences, learning, and environmental influences. This phenomenon is particularly significant in individuals with deafness, as the brain adapts to compensate for the lack of auditory stimulation. The aim of this study is to investigate whether cochlear implantation can restore a normal pattern of brain activation following auditory stimulation in cases of asymmetric hearing loss. We used a PET-scan technique to assess brain activity after cochlear implantation, specifically during an auditory voice/non-voice discrimination task. The results indicated a nearly normal pattern of brain activity during the auditory discrimination task, except for increased activation in areas related to attentional processes compared to controls. Additionally, brain activity at rest showed significant changes in implanted participants, including cross modal visuo-auditory processing. Therefore, cochlear implants can restore the brain's activation pattern through long-term adaptive adjustments in intrinsic brain activity.

A systematic review of acoustic change complex (ACC) measurements and applicability in children for the assessment of the neural capacity for sound and speech discrimination.

OBJECTIVE: The acoustic change complex (ACC) is a cortical auditory evoked potential (CAEP) and can be elicited by a change in an otherwise continuous sound. The ACC has been highlighted as a promising tool in the assessment of sound and speech discrimination capacity, and particularly for difficult-to-test populations such as infants with hearing loss, due to the objective nature of ACC measurements. Indeed, there is a pressing need to develop further means to accurately and thoroughly establish the hearing status of children with hearing loss, to help guide hearing interventions in a timely manner. Despite the potential of the ACC method, ACC measurements remain relatively rare in a standard clinical settings. The objective of this study was to perform an up-to-date systematic review on ACC measurements in children, to provide greater clarity and consensus on the possible methodologies, applications, and performance of this technique, and to facilitate its uptake in relevant clinical settings. DESIGN: Original peer-reviewed articles conducting ACC measurements in children (< 18 years). Data were extracted and summarised for: (1) participant characteristics; (2) ACC methods and auditory stimuli; (3) information related to the performance of the ACC technique; (4) ACC measurement outcomes, advantages, and challenges. The systematic review was conducted using PRISMA guidelines for reporting and the methodological quality of included articles was assessed. RESULTS: A total of 28 studies were identified (9 infant studies). Review results show that ACC responses can be measured in infants (from < 3 months), and there is evidence of age-dependency, including increased robustness of the ACC response with increasing childhood age. Clinical applications include the measurement of the neural capacity for speech and non-speech sound discrimination in children with hearing loss, auditory neuropathy spectrum disorder (ANSD) and central auditory processing disorder (CAPD). Additionally, ACCs can be recorded in children with hearing aids, auditory brainstem implants, and cochlear implants, and ACC results may guide hearing intervention/rehabilitation strategies. The review identified that the time taken to perform ACC measurements was often lengthy; the development of more efficient ACC test procedures for children would be beneficial. Comparisons between objective ACC measurements and behavioural measures of sound discrimination showed significant correlations for some, but not all, included studies. CONCLUSIONS: ACC measurements of the neural capacity to discriminate between speech and non-speech sounds are feasible in infants and children, and a wide range of possible clinical applications exist, although more time-efficient procedures would be advantageous for clinical uptake. A consideration of age and maturational effects is recommended, and further research is required to investigate the relationship between objective ACC measures and behavioural measures of sound and speech perception for effective clinical implementation.

Effects of pulse shape on pitch sensitivity of cochlear implant users.

Contemporary cochlear implants (CIs) use cathodic-leading symmetric biphasic (C-BP) pulses for electrical stimulation. It remains unclear whether asymmetric pulses emphasizing the anodic or cathodic phase may improve spectral and temporal coding with CIs. This study tested place- and temporal-pitch sensitivity with C-BP, anodic-centered triphasic (A-TP), and cathodic-centered triphasic (C-TP) pulse trains on apical, middle, and basal electrodes in 10 implanted ears. Virtual channel ranking (VCR) thresholds (for place-pitch sensitivity) were measured at both a low and a high pulse rate of 99 (Experiment 1) and 1000 (Experiment 2) pulses per second (pps), and amplitude modulation frequency ranking (AMFR) thresholds (for temporal-pitch sensitivity) were measured at a 1000-pps pulse rate in Experiment 3. All stimuli were presented in monopolar mode. Results of all experiments showed that detection thresholds, most comfortable levels (MCLs), VCR thresholds, and AMFR thresholds were higher on more basal electrodes. C-BP pulses had longer active phase duration and thus lower detection thresholds and MCLs than A-TP and C-TP pulses. Compared to C-TP pulses, A-TP pulses had lower detection thresholds at the 99-pps but not the 1000-pps pulse rate, and had lower MCLs at both pulse rates. A-TP pulses led to lower VCR thresholds than C-BP pulses, and in turn than C-TP pulses, at the 1000-pps pulse rate. However, pulse shape did not affect VCR thresholds at the 99-pps pulse rate (possibly due to the fixed temporal pitch) or AMFR thresholds at the 1000-pps pulse rate (where the overall high performance may have reduced the changes with different pulse shapes). Notably, stronger polarity effect on VCR thresholds (or more improvement in VCR with A-TP than with C-TP pulses) at the 1000-pps pulse rate was associated with stronger polarity effect on detection thresholds at the 99-pps pulse rate (consistent with more degeneration of auditory nerve peripheral processes). The results suggest that A-TP pulses may improve place-pitch sensitivity or spectral coding for CI users, especially in situations with peripheral process degeneration.