Non-auditory neurocognitive skills contribute to speech recognition in adults with cochlear implants

A Scoping Review and Meta-Analysis of the Relations Between Cognition and Cochlear Implant Outcomes and the Effect of Quiet Versus Noise Testing Conditions

OBJECTIVES

Evidence continues to emerge of associations between cochlear implant (CI) outcomes and cognitive functions in postlingually deafened adults. While there are multiple factors that appear to affect these associations, the impact of speech recognition background testing conditions (i.e., in quiet versus noise) has not been systematically explored. The two aims of this study were to (1) identify associations between speech recognition following cochlear implantation and performance on cognitive tasks, and to (2) investigate the impact of speech testing in quiet versus noise on these associations. Ultimately, we want to understand the conditions that impact this complex relationship between CI outcomes and cognition.

DESIGN

A scoping review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was performed on published literature evaluating the relation between outcomes of cochlear implantation and cognition. The current review evaluates 39 papers that reported associations between over 30 cognitive assessments and speech recognition tests in adult patients with CIs. Six cognitive domains were evaluated: Global Cognition, Inhibition-Concentration, Memory and Learning, Controlled Fluency, Verbal Fluency, and Visuospatial Organization. Meta-analysis was conducted on three cognitive assessments among 12 studies to evaluate relations with speech recognition outcomes. Subgroup analyses were performed to identify whether speech recognition testing in quiet versus in background noise impacted its association with cognitive performance.

RESULTS

Significant associations between cognition and speech recognition in a background of quiet or noise were found in 69% of studies. Tests of Global Cognition and Inhibition-Concentration skills resulted in the highest overall frequency of significant associations with speech recognition (45% and 57%, respectively). Despite the modest proportion of significant associations reported, pooling effect sizes across samples through meta-analysis revealed a moderate positive correlation between tests of Global Cognition (r = +0.37, p < 0.01) as well as Verbal Fluency (r = +0.44, p < 0.01) and postoperative speech recognition skills. Tests of Memory and Learning are most frequently utilized in the setting of CI (in 26 of 39 included studies), yet meta-analysis revealed nonsignificant associations with speech recognition performance in a background of quiet (r = +0.30, p = 0.18), and noise (r = -0.06, p = 0.78).

CONCLUSIONS

Background conditions of speech recognition testing may influence the relation between speech recognition outcomes and cognition. The magnitude of this effect of testing conditions on this relationship appears to vary depending on the cognitive construct being assessed. Overall, Global Cognition and Inhibition-Concentration skills are potentially useful in explaining speech recognition skills following cochlear implantation. Future work should continue to evaluate these relations to appropriately unify cognitive testing opportunities in the setting of cochlear implantation.

Task-Specific Rapid Auditory Perceptual Learning in Adult Cochlear Implant Recipients: What Could It Mean for Speech Recognition

OBJECTIVES

Speech recognition in cochlear implant (CI) recipients is quite variable, particularly in challenging listening conditions. Demographic, audiological, and cognitive factors explain some, but not all, of this variance. The literature suggests that rapid auditory perceptual learning explains unique variance in speech recognition in listeners with normal hearing and those with hearing loss. The present study focuses on the early adaptation phase of task-specific rapid auditory perceptual learning. It investigates whether adult CI recipients exhibit this learning and, if so, whether it accounts for portions of the variance in their recognition of fast speech and speech in noise.

DESIGN

Thirty-six adult CI recipients (ages = 35 to 77, M = 55) completed a battery of general speech recognition tests (sentences in speech-shaped noise, four-talker babble noise, and natural-fast speech), cognitive measures (vocabulary, working memory, attention, and verbal processing speed), and a rapid auditory perceptual learning task with time-compressed speech. Accuracy in the general speech recognition tasks was modeled with a series of generalized mixed models that accounted for demographic, audiological, and cognitive factors before accounting for the contribution of task-specific rapid auditory perceptual learning of time-compressed speech.

RESULTS

Most CI recipients exhibited early task-specific rapid auditory perceptual learning of time-compressed speech within the course of the first 20 sentences. This early task-specific rapid auditory perceptual learning had unique contribution to the recognition of natural-fast speech in quiet and speech in noise, although the contribution to natural-fast speech may reflect the rapid learning that occurred in this task. When accounting for demographic and cognitive characteristics, an increase of 1 SD in the early task-specific rapid auditory perceptual learning rate was associated with ~52% increase in the odds of correctly recognizing natural-fast speech in quiet, and ~19% to 28% in the odds of correctly recognizing the different types of speech in noise. Age, vocabulary, attention, and verbal processing speed also had unique contributions to general speech recognition. However, their contribution varied between the different general speech recognition tests.

CONCLUSIONS

Consistent with previous findings in other populations, in CI recipients, early task-specific rapid auditory perceptual, learning also accounts for some of the individual differences in the recognition of speech in noise and natural-fast speech in quiet. Thus, across populations, the early rapid adaptation phase of task-specific rapid auditory perceptual learning might serve as a skill that supports speech recognition in various adverse conditions. In CI users, the ability to rapidly adapt to ongoing acoustical challenges may be one of the factors associated with good CI outcomes. Overall, CI recipients with higher cognitive resources and faster rapid learning rates had better speech recognition.

Auditory, Visual, and Cognitive Abilities in Normal-Hearing Adults, Hearing Aid Users, and Cochlear Implant Users

OBJECTIVES

Speech understanding is considered a bimodal and bidirectional process, whereby visual information (i.e., speechreading) and also cognitive functions (i.e., top-down processes) are involved. Therefore, the purpose of the present study is twofold: (1) to investigate the auditory (A), visual (V), and cognitive (C) abilities in normal-hearing individuals, hearing aid (HA) users, and cochlear implant (CI) users, and (2) to determine an auditory, visual, cognitive (AVC)-profile providing a comprehensive overview of a person's speech processing abilities, containing a broader variety of factors involved in speech understanding.

DESIGN

Three matched groups of subjects participated in this study: (1) 31 normal-hearing adults (mean age = 58.76), (2) 31 adults with moderate to severe hearing loss using HAs (mean age = 59.31), (3) 31 adults with a severe to profound hearing loss using a CI (mean age = 58.86). The audiological assessments consisted of pure-tone audiometry, speech audiometry in quiet and in noise. For evaluation of the (audio-) visual speech processing abilities, the Test for (Audio) Visual Speech perception was used. The cognitive test battery consisted of the letter-number sequencing task, the letter detection test, and an auditory Stroop test, measuring working memory and processing speed, selective attention, and cognitive flexibility and inhibition, respectively. Differences between the three groups were examined using a one-way analysis of variance or Kruskal-Wallis test, depending on the normality of the variables. Furthermore, a principal component analysis was conducted to determine the AVC-profile.

RESULTS

Normal-hearing individuals scored better for both auditory, and cognitive abilities compared to HA users and CI users, listening in a best aided condition. No significant differences were found for speech understanding in a visual condition, despite a larger audiovisual gain for the HA users and CI users. Furthermore, an AVC-profile was composed based on the different auditory, visual, and cognitive assessments. On the basis of that profile, it is possible to determine one comprehensive score for auditory, visual, and cognitive functioning. In the future, these scores could be used in auditory rehabilitation to determine specific strengths and weaknesses per individual patient for the different abilities related to the process of speech understanding in daily life.

CONCLUSIONS

It is suggested to evaluate individuals with hearing loss from a broader perspective, considering more than only the typical auditory abilities. Also, cognitive and visual abilities are important to take into account to have a more complete overview of the speech understanding abilities in daily life.

Predicting Early Cochlear Implant Performance: Can Cognitive Testing Help?

Introduction

There is significant variability in speech recognition outcomes in adults who receive cochlear implants (CIs). Little is known regarding cognitive influences on very early CI performance, during which significant neural plasticity occurs.

Methods

Prospective study of 15 postlingually deafened adult CI candidates tested preoperatively with a battery of cognitive assessments. The mini-mental state exam (MMSE), forward digit span, Stroop measure of inhibition-concentration, and test of word reading efficiency were utilized to assess cognition. consonant-nucleus-consonant words, AZBio sentences in quiet, and AZBio sentences in noise (+10 dB SNR) were utilized to assess speech recognition at 1- and 3-months of CI use.

Results

Performance in all speech measures at 1-month was moderately correlated with preoperative MMSE, but these correlations were not strongly correlated after correcting for multiple comparisons. There were large correlations of forward digit span with 1-month AzBio quiet (P ≤ 0.001, rho = 0.762) and AzBio noise (P ≤ 0.001, rho = 0.860), both of which were strong after correction. At 3 months, forward digit span was strongly predictive of AzBio noise (P ≤ 0.001, rho = 0.786), which was strongly correlated after correction. Changes in speech recognition scores were not correlated with preoperative cognitive test scores.

Conclusions

Working memory capacity significantly predicted early CI sentence recognition performance in our small cohort, while other cognitive functions assessed did not. These results differ from prior studies predicting longer-term outcomes. Findings and further studies may lead to better preoperative counseling and help identify patients who require closer evaluation to ensure optimal CI performance.

Emerging Relations among Cognitive Constructs and Cochlear Implant Outcomes: A Systematic Review and Meta-Analysis

OBJECTIVE

Hearing loss has a detrimental impact on cognitive function. However, there is a lack of consensus on the impact of cochlear implants on cognition. This review systematically evaluates whether cochlear implants in adult patients lead to cognitive improvements and investigates the relations of cognition with speech recognition outcomes.

DATA SOURCES

A literature review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies evaluating cognition and cochlear implant outcomes in postlingual, adult patients from January 1996 to December 2021 were included. Of 2510 total references, 52 studies were included in qualitative analysis and 11 in meta-analyses.

REVIEW METHODS

Proportions were extracted from studies of (1) the significant impacts of cochlear implantation on 6 cognitive domains and (2) associations between cognition and speech recognition outcomes. Meta-analyses were performed using random effects models on mean differences between pre- and postoperative performance on 4 cognitive assessments.

RESULTS

Only half of the outcomes reported suggested cochlear implantation had a significant impact on cognition (50.8%), with the highest proportion in assessments of memory & learning and inhibition-concentration. Meta-analyses revealed significant improvements in global cognition and inhibition-concentration. Finally, 40.4% of associations between cognition and speech recognition outcomes were significant.

CONCLUSION

Findings relating to cochlear implantation and cognition vary depending on the cognitive domain assessed and the study goal. Nonetheless, assessments of memory & learning, global cognition, and inhibition-concentration may represent tools to assess cognitive benefit after implantation and help explain variability in speech recognition outcomes. Enhanced selectivity in assessments of cognition is needed for clinical applicability.

Plasticity After Hearing Rehabilitation in the Aging Brain

Age-related hearing loss, presbycusis, is an unavoidable sensory degradation, often associated with the progressive decline of cognitive and social functions, and dementia. It is generally considered a natural consequence of the inner-ear deterioration. However, presbycusis arguably conflates a wide array of peripheral and central impairments. Although hearing rehabilitation maintains the integrity and activity of auditory networks and can prevent or revert maladaptive plasticity, the extent of such neural plastic changes in the aging brain is poorly appreciated. By reanalyzing a large-scale dataset of more than 2200 cochlear implant users (CI) and assessing the improvement in speech perception from 6 to 24 months of use, we show that, although rehabilitation improves speech understanding on average, age at implantation only minimally affects speech scores at 6 months but has a pejorative effect at 24 months post implantation. Furthermore, older subjects (>67 years old) were significantly more likely to degrade their performances after 2 years of CI use than the younger patients for each year increase in age. Secondary analysis reveals three possible plasticity trajectories after auditory rehabilitation to account for these disparities: Awakening, reversal of deafness-specific changes; Counteracting, stabilization of additional cognitive impairments; or Decline, independent pejorative processes that hearing rehabilitation cannot prevent. The role of complementary behavioral interventions needs to be considered to potentiate the (re)activation of auditory brain networks.

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.

Cochlear Health and Cochlear-implant Function

The cochlear implant (CI) is widely considered to be one of the most innovative and successful neuroprosthetic treatments developed to date. Although outcomes vary, CIs are able to effectively improve hearing in nearly all recipients and can substantially improve speech understanding and quality of life for patients with significant hearing loss. A wealth of research has focused on underlying factors that contribute to success with a CI, and recent evidence suggests that the overall health of the cochlea could potentially play a larger role than previously recognized. This article defines and reviews attributes of cochlear health and describes procedures to evaluate cochlear health in humans and animal models in order to examine the effects of cochlear health on performance with a CI. Lastly, we describe how future biologic approaches can be used to preserve and/or enhance cochlear health in order to maximize performance for individual CI recipients.

Preoperative Reading Efficiency as a Predictor of Adult Cochlear Implant Outcomes

HYPOTHESES

1) Scores of reading efficiency (the Test of Word Reading Efficiency, second edition) obtained in adults before cochlear implant surgery will be predictive of speech recognition outcomes 6 months after surgery; and 2) Cochlear implantation will lead to improvements in language processing as measured through reading efficiency from preimplantation to postimplantation.

BACKGROUND

Adult cochlear implant (CI) users display remarkable variability in speech recognition outcomes. "Top-down" processing-the use of cognitive resources to make sense of degraded speech-contributes to speech recognition abilities in CI users. One area that has received little attention is the efficiency of lexical and phonological processing. In this study, a visual measure of word and nonword reading efficiency-relying on lexical and phonological processing, respectively-was investigated for its ability to predict CI speech recognition outcomes, as well as to identify any improvements after implantation.

METHODS

Twenty-four postlingually deaf adult CI candidates were tested on the Test of Word Reading Efficiency, Second Edition preoperatively and again 6 months post-CI. Six-month post-CI speech recognition measures were also assessed across a battery of word and sentence recognition.

RESULTS

Preoperative nonword reading scores were moderately predictive of sentence recognition outcomes, but real word reading scores were not; word recognition scores were not predicted by either. No 6-month post-CI improvement was demonstrated in either word or nonword reading efficiency.

CONCLUSION

Phonological processing as measured by the Test of Word Reading Efficiency, Second Edition nonword reading predicts to a moderate degree 6-month sentence recognition outcomes in adult CI users. Reading efficiency did not improve after implantation, although this could be because of the relatively short duration of CI use.

Factors affecting talker discrimination ability in adult cochlear implant users

INTRODUCTION

Real-world speech communication involves interacting with many talkers with diverse voices and accents. Many adults with cochlear implants (CIs) demonstrate poor talker discrimination, which may contribute to real-world communication difficulties. However, the factors contributing to talker discrimination ability, and how discrimination ability relates to speech recognition outcomes in adult CI users are still unknown. The current study investigated talker discrimination ability in adult CI users, and the contributions of age, auditory sensitivity, and neurocognitive skills. In addition, the relation between talker discrimination ability and multiple-talker sentence recognition was explored.

METHODS

Fourteen post-lingually deaf adult CI users (3 female, 11 male) with ≥1 year of CI use completed a talker discrimination task. Participants listened to two monosyllabic English words, produced by the same talker or by two different talkers, and indicated if the words were produced by the same or different talkers. Nine female and nine male native English talkers were paired, resulting in same- and different-talker pairs as well as same-gender and mixed-gender pairs. Participants also completed measures of spectro-temporal processing, neurocognitive skills, and multiple-talker sentence recognition.

RESULTS

CI users showed poor same-gender talker discrimination, but relatively good mixed-gender talker discrimination. Older age and weaker neurocognitive skills, in particular inhibitory control, were associated with less accurate mixed-gender talker discrimination. Same-gender discrimination was significantly related to multiple-talker sentence recognition accuracy.

CONCLUSION

Adult CI users demonstrate overall poor talker discrimination ability. Individual differences in mixed-gender discrimination ability were related to age and neurocognitive skills, suggesting that these factors contribute to the ability to make use of available, degraded talker characteristics. Same-gender talker discrimination was associated with multiple-talker sentence recognition, suggesting that access to subtle talker-specific cues may be important for speech recognition in challenging listening conditions.

Poor Performer: A Distinct Entity in Cochlear Implant Users?

INTRODUCTION

Several factors are known to influence speech perception in cochlear implant (CI) users. To date, the underlying mechanisms have not yet been fully clarified. Although many CI users achieve a high level of speech perception, a small percentage of patients does not or only slightly benefit from the CI (poor performer, PP). In a previous study, PP showed significantly poorer results on nonauditory-based cognitive and linguistic tests than CI users with a very high level of speech understanding (star performer, SP). We now investigate if PP also differs from the CI user with an average performance (average performer, AP) in cognitive and linguistic performance.

METHODS

Seventeen adult postlingually deafened CI users with speech perception scores in quiet of 55 (9.32) % (AP) on the German Freiburg monosyllabic speech test at 65 dB underwent neurocognitive (attention, working memory, short- and long-term memory, verbal fluency, inhibition) and linguistic testing (word retrieval, lexical decision, phonological input lexicon). The results were compared to the performance of 15 PP (speech perception score of 15 [11.80] %) and 19 SP (speech perception score of 80 [4.85] %). For statistical analysis, U-Test and discrimination analysis have been done.

RESULTS

Significant differences between PP and AP were observed on linguistic tests, in Rapid Automatized Naming (RAN: p = 0.0026), lexical decision (LexDec: p = 0.026), phonological input lexicon (LEMO: p = 0.0085), and understanding of incomplete words (TRT: p = 0.0024). AP also had significantly better neurocognitive results than PP in the domains of attention (M3: p = 0.009) and working memory (OSPAN: p = 0.041; RST: p = 0.015) but not in delayed recall (delayed recall: p = 0.22), verbal fluency (verbal fluency: p = 0.084), and inhibition (Flanker: p = 0.35). In contrast, no differences were found hereby between AP and SP. Based on the TRT and the RAN, AP and PP could be separated in 100%.

DISCUSSION

The results indicate that PP constitute a distinct entity of CI users that differs even in nonauditory abilities from CI users with an average speech perception, especially with regard to rapid word retrieval either due to reduced phonological abilities or limited storage. Further studies should investigate if improved word retrieval by increased phonological and semantic training results in better speech perception in these CI users.

Impacts of signal processing factors on perceptual restoration in cochlear-implant users

Cochlear-implant (CI) users have previously demonstrated perceptual restoration, or successful repair of noise-interrupted speech, using the interrupted sentences paradigm [Bhargava, Gaudrain, and Başkent (2014). "Top-down restoration of speech in cochlear-implant users," Hear. Res. 309, 113-123]. The perceptual restoration effect was defined experimentally as higher speech understanding scores with noise-burst interrupted sentences compared to silent-gap interrupted sentences. For the perceptual restoration illusion to occur, it is often necessary for the masking or interrupting noise bursts to have a higher intensity than the adjacent speech signal to be perceived as a plausible masker. Thus, signal processing factors like noise reduction algorithms and automatic gain control could have a negative impact on speech repair in this population. Surprisingly, evidence that participants with cochlear implants experienced the perceptual restoration illusion was not observed across the two planned experiments. A separate experiment, which aimed to provide a close replication of previous work on perceptual restoration in CI users, also found no consistent evidence of perceptual restoration, contrasting the original study's previously reported findings. Typical speech repair of interrupted sentences was not observed in the present work's sample of CI users, and signal-processing factors did not appear to affect speech repair.

Preoperative Visual Measures of Verbal Learning and Memory and their Relations to Speech Recognition After Cochlear Implantation

OBJECTIVES

This study examined the performance of a group of adult cochlear implant (CI) candidates (CIC) on visual tasks of verbal learning and memory. Preoperative verbal learning and memory abilities of the CIC group were compared with a group of older normal-hearing (ONH) control participants. Relations between preoperative verbal learning and memory measures and speech recognition outcomes after 6 mo of CI use were also investigated for a subgroup of the CICs.

DESIGN

A group of 80 older adult participants completed a visually presented multitrial free recall task. Measures of word recall, repetition learning, and the use of self-generated organizational strategies were collected from a group of 49 CICs, before cochlear implantation, and a group of 31 ONH controls. Speech recognition outcomes were also collected from a subgroup of 32 of the CIC participants who returned for testing 6 mo after CI activation.

RESULTS

CICs demonstrated poorer verbal learning performance compared with the group of ONH control participants. Among the preoperative verbal learning and memory measures, repetition learning slope and measures of self-generated organizational clustering strategies were the strongest predictors of post-CI speech recognition outcomes.

CONCLUSIONS

Older adult CI candidates present with verbal learning and memory deficits compared with older adults without hearing loss, even on visual tasks that are independent from the direct effects of audibility. Preoperative verbal learning and memory processes reflecting repetition learning and self-generated organizational strategies in free recall were associated with speech recognition outcomes 6 months after implantation. The pattern of results suggests that visual measures of verbal learning may be a useful predictor of outcomes in postlingual adult CICs.

Cochlear Implant Results in Older Adults with Post-Lingual Deafness: The Role of “Top-Down” Neurocognitive Mechanisms

To date, no clear specific cognitive predictors of speech perception outcome in older adult cochlear implant (CI) users have yet emerged. The aim of this prospective study was to increase knowledge on cognitive and clinical predictors of the audiological outcome in adult cochlear implant users. A total of 21 patients with post-lingual deafness, who were candidates for cochlear implantation, were recruited at the Department of Ear, Nose and Throat, University of Torino (Italy) and subjected to a pre-operatory neuropsychological assessment (T0) and an audiological examination after 12 months of implantation (T12). Patients who, at T12, had a 60 dB verbal recognition above 80%, were younger (z = −2.131, p = 0.033) and performed better in the Verbal Semantic Fluency Test at T0 (z = −1.941, p = 0.052) than subjects who had a 60 dB verbal recognition at T12 below 80%. The most significant predictors of the CI audiological outcome at T12 were age (β = −0.492, p = 0.024) and patients’ TMT-A performance at baseline (β = −0.486, p = 0.035). We conclude that cognitive processing speed might be a good predictor of the level of speech understanding in older adult patients with CI after one year of implantation.

Using Clinical Audiologic Measures to Determine Cochlear Implant Candidacy

INTRODUCTION

Only a small percentage (6-10%) of patients who are candidates receive cochlear implants (CIs). One potential reason contributing to low usage rates may be confusion regarding which patients to refer for CI evaluation. The extent to which information provided by standard clinical audiologic assessments is sufficient for selecting appropriate CI evaluation referrals is uncertain. The objective of this study is to evaluate the capacity of standard clinical audiologic measures to differentiate CI candidates from noncandidates.

METHOD

The study design is a retrospective review of a prospectively maintained CI database from a university-based tertiary medical center of 518 patients undergoing CI evaluations from 2012 to 2020. Each ear of each patient was treated as an independent value. Receiver operating characteristic (ROCs) curves were constructed using aided AzBio sentence recognition scores in quiet and aided AzBio +10 dB signal-to-noise ratio scores <60% as binary classifiers for CI candidacy. For each ROC, we examined the capacity of multiple pure-tone thresholds, pure-tone average (PTA), and CNC word recognition scores (WRSs) measured under earphones to determine CI candidacy. Area under the curve ROC (AUC-ROC) values were calculated to demonstrate the capacity of each model to differentiate CI candidates from noncandidates.

RESULTS

Variables with the greatest capacity to accurately differentiate CI candidates from noncandidates using aided AzBio in quiet scores were earphone CNC WRS, earphone pure-tone threshold at 1,000 Hz, and earphone PTA (AUC-ROC values = 0.86-0.88). Using aided AzBio +10 scores as the measure for candidacy, only CNC word recognition had a fair capacity to identify candidates (AUC-ROC value = 0.73). Based on the ROCs, a 1,000 Hz pure-tone threshold >50 dB HL, PTA >57 dB HL, and a monosyllabic WRS <60% can each serve as individual indicators for referral for CI evaluations.

CONCLUSION

The current study provides initial indicators for referral and a first step at developing evidence-based criteria for CI evaluation referral using standard audiologic assessments.

More Than Words: the Relative Roles of Prosody and Semantics in the Perception of Emotions in Spoken Language by Postlingual Cochlear Implant Users

OBJECTIVES

The processing of emotional speech calls for the perception and integration of semantic and prosodic cues. Although cochlear implants allow for significant auditory improvements, they are limited in the transmission of spectro-temporal fine-structure information that may not support the processing of voice pitch cues. The goal of the current study is to compare the performance of postlingual cochlear implant (CI) users and a matched control group on perception, selective attention, and integration of emotional semantics and prosody.

DESIGN

Fifteen CI users and 15 normal hearing (NH) peers (age range, 18-65 years) 1istened to spoken sentences composed of different combinations of four discrete emotions (anger, happiness, sadness, and neutrality) presented in prosodic and semantic channels-T-RES: Test for Rating Emotions in Speech. In three separate tasks, listeners were asked to attend to the sentence as a whole, thus integrating both speech channels (integration), or to focus on one channel only (rating of target emotion) and ignore the other (selective attention). Their task was to rate how much they agreed that the sentence conveyed each of the predefined emotions. In addition, all participants performed standard tests of speech perception.

RESULTS

When asked to focus on one channel, semantics or prosody, both groups rated emotions similarly with comparable levels of selective attention. When the task was called for channel integration, group differences were found. CI users appeared to use semantic emotional information more than did their NH peers. CI users assigned higher ratings than did their NH peers to sentences that did not present the target emotion, indicating some degree of confusion. In addition, for CI users, individual differences in speech comprehension over the phone and identification of intonation were significantly related to emotional semantic and prosodic ratings, respectively.

CONCLUSIONS

CI users and NH controls did not differ in perception of prosodic and semantic emotions and in auditory selective attention. However, when the task called for integration of prosody and semantics, CI users overused the semantic information (as compared with NH). We suggest that as CI users adopt diverse cue weighting strategies with device experience, their weighting of prosody and semantics differs from those used by NH. Finally, CI users may benefit from rehabilitation strategies that strengthen perception of prosodic information to better understand emotional speech.

The effects of stimulus modality, task complexity, and cuing on working memory and the relationship with speech recognition in older cochlear implant users

INTRODUCTION

The role of working memory (WM) in speech recognition of older cochlear implant (CI) users remains unclear. This study 1) examined the effects of aging and CI on WM performance across different modalities (auditory vs. visual) and cuing conditions, and 2) assessed how specific WM measures relate to sentence and word recognition in noise.

METHOD

Fourteen Older CI users, 12 Older acoustic-hearing (AH) listeners with age-appropriate hearing loss, and 15 Young normal-hearing (NH) listeners were tested. Participants completed two simple span tasks (auditory digit and visual letter span), two complex WM tasks (reading span and cued-modality WM with simultaneously presented auditory digits and visual letters), and two speech recognition tasks (sentence and word recognition in speech-babble noise).

RESULTS

The groups showed similar simple span performance, except that Older CI users had lower auditory digit span than Young NH listeners. Both older groups had similar reading span performance, but scored significantly lower than Young NH listeners, indicating age-related declines in attentional and phonological processing. A similar group effect was observed in the cued-modality WM task. All groups showed higher recall for auditory digits than for visual letters and the advantage was most evident without modality cuing. All groups displayed greater cuing benefits for visual recall than for auditory recall, suggesting that participants consistently allocated more attention to auditory stimuli regardless of cuing. For Older CI users, after controlling for the previously reported spectral resolution, auditory-uncued WM performance was significantly correlated with word recognition but not sentence recognition.

CONCLUSIONS

Complex WM was significantly affected by aging but not by CI. Neither aging nor CI significantly affected modality cuing benefits in the WM task. For Older CI users, complex auditory WM with attentional control may better reflect the cognitive load of speech recognition in noise than simple span or complex visual WM.

The Impact of Neurocognitive Skills on Recognition of Spectrally Degraded Sentences

BACKGROUND

 Recent models theorize that neurocognitive resources are deployed differently during speech recognition depending on task demands, such as the severity of degradation of the signal or modality (auditory vs. audiovisual [AV]). This concept is particularly relevant to the adult cochlear implant (CI) population, considering the large amount of variability among CI users in their spectro-temporal processing abilities. However, disentangling the effects of individual differences in spectro-temporal processing and neurocognitive skills on speech recognition in clinical populations of adult CI users is challenging. Thus, this study investigated the relationship between neurocognitive functions and recognition of spectrally degraded speech in a group of young adult normal-hearing (NH) listeners.

PURPOSE

 The aim of this study was to manipulate the degree of spectral degradation and modality of speech presented to young adult NH listeners to determine whether deployment of neurocognitive skills would be affected.

RESEARCH DESIGN

 Correlational study design.

STUDY SAMPLE

 Twenty-one NH college students.

DATA COLLECTION AND ANALYSIS

 Participants listened to sentences in three spectral-degradation conditions: no degradation (clear sentences); moderate degradation (8-channel noise-vocoded); and high degradation (4-channel noise-vocoded). Thirty sentences were presented in an auditory-only (A-only) modality and an AV fashion. Visual assessments from The National Institute of Health Toolbox Cognitive Battery were completed to evaluate working memory, inhibition-concentration, cognitive flexibility, and processing speed. Analyses of variance compared speech recognition performance among spectral degradation condition and modality. Bivariate correlation analyses were performed among speech recognition performance and the neurocognitive skills in the various test conditions.

RESULTS

 Main effects on sentence recognition were found for degree of degradation (p = < 0.001) and modality (p = < 0.001). Inhibition-concentration skills moderately correlated (r = 0.45, p = 0.02) with recognition scores for sentences that were moderately degraded in the A-only condition. No correlations were found among neurocognitive scores and AV speech recognition scores.

CONCLUSIONS

 Inhibition-concentration skills are deployed differentially during sentence recognition, depending on the level of signal degradation. Additional studies will be required to study these relations in actual clinical populations such as adult CI users.

Bottom-Up Signal Quality Impacts the Role of Top-Down Cognitive-Linguistic Processing During Speech Recognition by Adults with Cochlear Implants

HYPOTHESES

Significant variability persists in speech recognition outcomes in adults with cochlear implants (CIs). Sensory ("bottom-up") and cognitive-linguistic ("top-down") processes help explain this variability. However, the interactions of these bottom-up and top-down factors remain unclear. One hypothesis was tested: top-down processes would contribute differentially to speech recognition, depending on the fidelity of bottom-up input.

BACKGROUND

Bottom-up spectro-temporal processing, assessed using a Spectral-Temporally Modulated Ripple Test (SMRT), is associated with CI speech recognition outcomes. Similarly, top-down cognitive-linguistic skills relate to outcomes, including working memory capacity, inhibition-concentration, speed of lexical access, and nonverbal reasoning.

METHODS

Fifty-one adult CI users were tested for word and sentence recognition, along with performance on the SMRT and a battery of cognitive-linguistic tests. The group was divided into "low-," "intermediate-," and "high-SMRT" groups, based on SMRT scores. Separate correlation analyses were performed for each subgroup between a composite score of cognitive-linguistic processing and speech recognition.

RESULTS

Associations of top-down composite scores with speech recognition were not significant for the low-SMRT group. In contrast, these associations were significant and of medium effect size (Spearman's rho = 0.44-0.46) for two sentence types for the intermediate-SMRT group. For the high-SMRT group, top-down scores were associated with both word and sentence recognition, with medium to large effect sizes (Spearman's rho = 0.45-0.58).

CONCLUSIONS

Top-down processes contribute differentially to speech recognition in CI users based on the quality of bottom-up input. Findings have clinical implications for individualized treatment approaches relying on bottom-up device programming or top-down rehabilitation approaches.

Talker Adaptation and Lexical Difficulty Impact Word Recognition in Adults with Cochlear Implants

INTRODUCTION

Talker-specific adaptation facilitates speech recognition in normal-hearing listeners. This study examined talker adaptation in adult cochlear implant (CI) users. Three hypotheses were tested: (1) high-performing adult CI users show improved word recognition following exposure to a talker ("talker adaptation"), particularly for lexically hard words, (2) individual performance is determined by auditory sensitivity and neurocognitive skills, and (3) individual performance relates to real-world functioning.

METHODS

Fifteen high-performing, post-lingually deaf adult CI users completed a word recognition task consisting of 6 single-talker blocks (3 female/3 male native English speakers); words were lexically "easy" and "hard." Recognition accuracy was assessed "early" and "late" (first vs. last 10 trials); adaptation was assessed as the difference between late and early accuracy. Participants also completed measures of spectral-temporal processing and neurocognitive skills, as well as real-world measures of multiple-talker sentence recognition and quality of life (QoL).

RESULTS

CI users showed limited talker adaptation overall, but performance improved for lexically hard words. Stronger spectral-temporal processing and neurocognitive skills were weakly to moderately associated with more accurate word recognition and greater talker adaptation for hard words. Finally, word recognition accuracy for hard words was moderately related to multiple-talker sentence recognition and QoL.

CONCLUSION

Findings demonstrate a limited talker adaptation benefit for recognition of hard words in adult CI users. Both auditory sensitivity and neurocognitive skills contribute to performance, suggesting additional benefit from adaptation for individuals with stronger skills. Finally, processing differences related to talker adaptation and lexical difficulty may be relevant to real-world functioning.

Cochlear implant in prelingually hearing-impaired adults: prognostic factors and results

Objectives

The aim of present study is to evaluate the impact of prognostic factors on the outcome in a group of prelingually hearing-impaired patients submitted to cochlear implantation (CI) at an adult age.

Methods

This is a retrospective study on a cohort of prelingually severe-to-profound hearing-impaired patients cochlear implanted in adulthood and followed by a single audiology centre. We correlated post-CI results in term of speech perception with patients’ speech perception with hearing aids before implantation, history of progression of hearing loss (HL), and levels of education and cognition. The study group was composed of 49 patients.

Results

Post-CI open-set recognition score in silence and noise was significantly correlated with pre-CI open-set recognition score in silence and with background noise. Patients with a history of progression of HL gained significantly better results. Furthermore, we found higher improvements in patients with a higher level of education.

Conclusions

Prelingually deafened patients implanted in adulthood achieved satisfactory results. Significantly better results were achieved by patients with better pre-operative speech perception scores, progressive HL and higher level of education.

Relationship Between Electrocochleography, Angular Insertion Depth, and Cochlear Implant Speech Perception Outcomes

OBJECTIVES

Electrocochleography (ECochG), obtained before the insertion of a cochlear implant (CI) array, provides a measure of residual cochlear function that accounts for a substantial portion of variability in postoperative speech perception outcomes in adults. It is postulated that subsequent surgical factors represent independent sources of variance in outcomes. Prior work has demonstrated a positive correlation between angular insertion depth (AID) of straight arrays and speech perception under the CI-alone condition, with an inverse relationship observed for precurved arrays. The purpose of the present study was to determine the combined effects of ECochG, AID, and array design on speech perception outcomes.

DESIGN

Participants were 50 postlingually deafened adult CI recipients who received one of three straight arrays (MED-EL Flex24, MED-EL Flex28, and MED-EL Standard) and two precurved arrays (Cochlear Contour Advance and Advanced Bionics HiFocus Mid-Scala). Residual cochlear function was determined by the intraoperative ECochG total response (TR) measured before array insertion, which is the sum of magnitudes of spectral components in response to tones of different stimulus frequencies across the speech spectrum. The AID was then determined with postoperative imaging. Multiple linear regression was used to predict consonant-nucleus-consonant (CNC) word recognition in the CI-alone condition at 6 months postactivation based on AID, TR, and array design.

RESULTS

Forty-one participants received a straight array and nine received a precurved array. The AID of the most apical electrode contact ranged from 341° to 696°. The TR measured by ECochG accounted for 43% of variance in speech perception outcomes (p < 0.001). A regression model predicting CNC word scores with the TR tended to underestimate the performance for precurved arrays and deeply inserted straight arrays, and to overestimate the performance for straight arrays with shallower insertions. When combined in a multivariate linear regression, the TR, AID, and array design accounted for 72% of variability in speech perception outcomes (p < 0.001).

CONCLUSIONS

A model of speech perception outcomes that incorporates TR, AID, and array design represents an improvement over a model based on TR alone. The success of this model shows that peripheral factors including cochlear health and electrode placement may play a predominant role in speech perception with CIs.

Forward Digit Span and Word Familiarity Do Not Correlate With Differences in Speech Recognition in Individuals With Cochlear Implants After Accounting for Auditory Resolution

Purpose In individuals with cochlear implants, speech recognition is not associated with tests of working memory that primarily reflect storage, such as forward digit span. In contrast, our previous work found that vocoded speech recognition in individuals with normal hearing was correlated with performance on a forward digit span task. A possible explanation for this difference across groups is that variability in auditory resolution across individuals with cochlear implants could conceal the true relationship between speech and memory tasks. Here, our goal was to determine if performance on forward digit span and speech recognition tasks are correlated in individuals with cochlear implants after controlling for individual differences in auditory resolution. Method We measured sentence recognition ability in 20 individuals with cochlear implants with Perceptually Robust English Sentence Test Open-set sentences. Spectral and temporal modulation detection tasks were used to assess individual differences in auditory resolution, auditory forward digit span was used to assess working memory storage, and self-reported word familiarity was used to assess vocabulary. Results Individual differences in speech recognition were predicted by spectral and temporal resolution. A correlation was found between forward digit span and speech recognition, but this correlation was not significant after controlling for spectral and temporal resolution. No relationship was found between word familiarity and speech recognition. Forward digit span performance was not associated with individual differences in auditory resolution. Conclusions Our findings support the idea that sentence recognition in individuals with cochlear implants is primarily limited by individual differences in working memory processing, not storage. Studies examining the relationship between speech and memory should control for individual differences in auditory resolution.

The Value of Speech-Language Pathologists in Auditory Rehabilitation for Adults With Cochlear Implants

Background Standards for auditory rehabilitation are currently lacking for adults who receive cochlear implants. Speech recognition outcomes are highly variable, and many adults with cochlear implants present with suboptimal performance. Functional real-life communication abilities are not routinely measured clinically and are not strongly linked to performance on traditional measures of speech recognition. In fact, even individuals with relatively good speech recognition outcomes often present with persistent communication difficulties. In contrast to pediatric cochlear implant users, speech-language pathologists are not routinely involved in the rehabilitation of adults who receive cochlear implants. Purpose The purpose of this article is to describe the value of including a speech-language pathologist in a comprehensive approach to auditory rehabilitation for adults with cochlear implants. Method The theoretical and clinical foundations of incorporating a speech-language pathologist into an adult auditory rehabilitation program are discussed. A description of the skills and potential roles of the speech-language pathologist for providing adult cochlear implant rehabilitation services is presented, along with potential barriers to implementation. Conclusion Person-centered management of postlingually deafened adults with cochlear implants can be augmented by a more complete approach utilizing the skill set of a speech-language pathologist. Supplemental Material https://doi.org/10.23641/asha.14669652.

Can a Self-report Measure Be Used to Assess Cognitive Skills in Adults With Hearing Loss?

HYPOTHESES

Adult cochlear implant candidates would self-report their executive functioning abilities as poorer than normal-hearing peers. These executive function abilities would correlate with laboratory-based cognitive tests. Lastly, executive functioning (EF) abilities would be associated with hearing-related quality of life.

BACKGROUND

Executive function refers to cognitive abilities involved in behavioral regulation during goal-directed activity. Pediatric and adult users have demonstrated delays and deficits in executive function skills compared with normal-hearing peers. This study aimed to compare self-report executive function in adult cochlear implant candidates and normal-hearing peers and to relate executive function skills to laboratory-based cognitive testing and hearing-related quality of life.

METHODS

Twenty-four postlingually deaf adult cochlear implant candidates were enrolled, along with 42 normal-hearing age-matched peers. Participants completed self-reports of executive function using the Behavior Rating Inventory of Executive Function- Adult (BRIEF-A). Participants were also tested using laboratory-based cognitive measures, as well as assessment of hearing-related quality of life on the Nijmegen Cochlear Implant Questionnaire. Groups were compared on BRIEF-A scores, and relations between BRIEF-A and lab-based cognitive measures as well as Nijmegen Cochlear Implant Questionnaire scores were examined.

RESULTS

Self-report executive function on the BRIEF-A was not significantly different between groups. Consistent relations of self-report executive function and nonverbal reasoning were identified. Strong relations were not found between self-report executive function and hearing-related quality of life.

CONCLUSIONS

Executive function as measured by BRIEF-A demonstrates some relation with a laboratory-based metric of nonverbal reasoning, but not other cognitive measures. Hearing-impaired individuals did not report poorer EF than normal-hearing controls. EF additionally did not correlate with quality of life. Our findings provide preliminary, partial validation of the BRIEF-A instrument in the preoperative evaluation of adult cochlear implant candidates.

Neural correlates of visual stimulus encoding and verbal working memory differ between cochlear implant users and normal-hearing controls

A common concern for individuals with severe‐to‐profound hearing loss fitted with cochlear implants (CIs) is difficulty following conversations in noisy environments. Recent work has suggested that these difficulties are related to individual differences in brain function, including verbal working memory and the degree of cross‐modal reorganization of auditory areas for visual processing. However, the neural basis for these relationships is not fully understood. Here, we investigated neural correlates of visual verbal working memory and sensory plasticity in 14 CI users and age‐matched normal‐hearing (NH) controls. While we recorded the high‐density electroencephalogram (EEG), participants completed a modified Sternberg visual working memory task where sets of letters and numbers were presented visually and then recalled at a later time. Results suggested that CI users had comparable behavioural working memory performance compared with NH. However, CI users had more pronounced neural activity during visual stimulus encoding, including stronger visual‐evoked activity in auditory and visual cortices, larger modulations of neural oscillations and increased frontotemporal connectivity. In contrast, during memory retention of the characters, CI users had descriptively weaker neural oscillations and significantly lower frontotemporal connectivity. We interpret the differences in neural correlates of visual stimulus processing in CI users through the lens of cross‐modal and intramodal plasticity.

Visuospatial and Tactile Working Memory in Individuals with Congenital Deafness

Studies examining visuospatial working memory (WM) in individuals with congenital deafness have yielded inconsistent results, and tactile WM has rarely been examined. The current study examined WM span tasks in the two modalities among 20 individuals with congenital deafness and 20 participants with typical hearing. The congenital deafness group had longer forward and backward spans than typical hearing participants in a computerized Corsi block-tapping test (Visuospatial Span), whereas no such difference was found in the Tactual Span (tactile WM). In the congenital deafness group, age of sign language acquisition was not correlated with either condition of the visuospatial task, and Tactual and Visuospatial Spans scores were correlated in the backward but not the forward condition. The typical hearing group showed no correlation between the tasks. The findings suggest that early deafness leads to visuospatial but not tactile superiority in WM, specifically with respect to the storage component. More broadly, it appears that deafness-related compensation mechanisms in WM do not affect the other modalities in a uniform manner.

Nonauditory Functions in Low-performing Adult Cochlear Implant Users

INTRODUCTION

Despite substantial benefits of cochlear implantation (CI) there is a high variability in speech recognition, the reasons for which are not fully understood. Especially the group of low-performing CI users is under-researched. Because of limited perceptual quality, top-down mechanisms play an important role in decoding the speech signal transmitted by the CI. Thereby, differences in cognitive functioning and linguistic skills may explain speech outcome in these CI subjects.

MATERIAL AND METHODS

Fifteen post-lingually deaf CI recipients with a maximum speech perception of 30% in the Freiburger monosyllabic test (low performer = LP) underwent visually presented neurocognitive and linguistic test batteries assessing attention, memory, inhibition, working memory, lexical access, phonological input as well as automatic naming. Nineteen high performer (HP) with a speech perception of more than 70% were included as a control. Pairwise comparison of the two extreme groups and discrimination analysis were carried out.

RESULTS

Significant differences were found between LP and HP in phonological input lexicon and word retrieval (p = 0.0039∗∗). HP were faster in lexical access (p = 0.017∗) and distinguished more reliably between non-existing and existing words (p = 0.0021∗∗). Furthermore, HP outperformed LP in neurocognitive subtests, most prominently in attention (p = 0.003∗∗). LP and HP were primarily discriminated by linguistic performance and to a smaller extent by cognitive functioning (canonic r = 0.68, p = 0.0075). Poor rapid automatic naming of numbers helped to discriminate LP from HP CI users 91.7% of the time.

CONCLUSION

Severe phonologically based deficits in fast automatic speech processing contribute significantly to distinguish LP from HP CI users. Cognitive functions might partially help to overcome these difficulties.

Cognitive Functions in Adults Receiving Cochlear Implants: Predictors of Speech Recognition and Changes After Implantation

HYPOTHESES

Significant variability in speech recognition outcomes is consistently observed in adults who receive cochlear implants (CIs), some of which may be attributable to cognitive functions. Two hypotheses were tested: 1) preoperative cognitive skills assessed visually would predict postoperative speech recognition at 6 months after CI; and 2) cochlear implantation would result in benefits to cognitive processes at 6 months.

BACKGROUND

Several executive functioning tasks have been identified as contributors to speech recognition in adults with hearing loss. There is also mounting evidence that cochlear implantation can improve cognitive functioning. This study examined whether preoperative cognitive functions would predict speech recognition after implantation, and whether cognitive skills would improve as a result of CI intervention.

METHODS

Nineteen post-lingually deafened adult CI candidates were tested preoperatively using a visual battery of tests to assess working memory (WM), processing speed, inhibition-concentration, and nonverbal reasoning. Six months post-implantation, participants were assessed with a battery of word and sentence recognition measures and cognitive tests were repeated.

RESULTS

Multiple speech measures after 6 months of CI use were correlated with preoperative visual WM (symbol span task) and inhibition ability (stroop incongruent task) with moderate-to-large effect sizes. Small-to-large effect size improvements in visual WM, concentration, and inhibition tasks were found from pre- to post-CI. Patients with lower baseline cognitive abilities improved the most after implantation.

CONCLUSIONS

Findings provide evidence that preoperative cognitive factors contribute to speech recognition outcomes for adult CI users, and support the premise that implantation may lead to improvements in some cognitive domains.

A surgeon-scientist's perspective and review of cognitive-linguistic contributions to adult cochlear implant outcomes

OBJECTIVES

Enormous variability in speech recognition outcomes persists in adults who receive cochlear implants (CIs), which leads to a barrier to progress in predicting outcomes before surgery, explaining "poor" outcomes, and determining how to provide tailored rehabilitation therapy for individual CI users. The primary goal of my research program over the past 9 years has been to extend our understanding of the contributions of "top-down" cognitive-linguistic skills to CI outcomes in adults, acknowledging that "bottom-up" sensory processes also contribute substantially. The main objective of this invited narrative review is to provide an overview of this work. A secondary objective is to provide career "guidance points" to budding surgeon-scientists in Otolaryngology.

METHODS

A narrative, chronological review covers work done by our group to explore top-down and bottom-up processing in adult CI outcomes. A set of ten guidance points is also provided to assist junior Otolaryngology surgeon-scientists.

RESULTS

Work in our lab has identified substantial contributions of cognitive skills (working memory, inhibition-concentration, speed of lexical access, nonverbal reasoning, verbal learning and memory) as well as linguistic abilities (acoustic cue-weighting, phonological sensitivity) to speech recognition outcomes in adults with CIs. These top-down skills interact with the quality of the bottom-up input.

CONCLUSION

Although progress has been made in understanding speech recognition variability in adult CI users, future work is needed to predict CI outcomes before surgery, to identify particular patients' strengths and weaknesses, and to tailor rehabilitation approaches for individual CI users.

LEVEL OF EVIDENCE

4.

Benefits of Cochlear Implantation in Middle-Aged and Older Adults

Introduction

Nowadays cochlear implantation (CI) is the treatment of choice in adults in case conventional hearing devices fail. Besides speech perception, an improvement in quality of life and in cognitive performance has been reported. Thereby, the study focused on the impact of age.

Participants and Methods

Thirty middle-aged (MA) between 50 and 64 years and 41 older subjects (OA) aged 65 and older with bilateral severe hearing loss performed a comprehensive computer-based neurocognitive test battery (ALAcog) pre- and 12 months post-implantation. Besides, monosyllabic speech perception in quiet (Freiburg monosyllabic speech test), health-related quality of life (HR-QoL, Nijmegen Cochlear Implant Questionnaire) and depressive symptoms (GDS-15) have been assessed.

Results

Both age groups significantly improved in all three categories after 12 months. No differences were evaluated between MA and OA regarding speech perception and HR-QoL pre- and post-operatively. In contrast, cognitive performance differed between the age groups: pre-operatively OA performed worse in most neurocognitive subdomains like working memory (p=0.04), inhibition (p=0.004), processing speed (p=0.003) and mental flexibility (p=0.01), post-operatively MA outperformed OA only in inhibition (p=0.01). Age only slightly influenced cognitive performance in MA, whereas in OA age per se tremendously impacted on working memory (p=0.04), inhibition (p=0.02), memory (p=0.04) and mental flexibility (p=0.01). Educational level also affected processing speed, mental flexibility (p=0.01) and working memory (p=0.01). This was more pronounced in OA. In both age groups, hearing status had a strong effect on attentional tasks (p=0.01). In MA, depressive symptoms were more influential on cognitive functioning and on HR-QoL than in OA. Improvement in quality of life (p=0.0002) and working memory (p=0.001) was greater for those with a higher pre-operative depression score.

Conclusion

Speech perception and HR-QoL improved in hearing impaired, independently of age. Pre-operative differences in cognitive performance between OA and MA clearly attenuated 12 months after CI. Impact of comorbidities differed between age groups.

Explaining Speech Recognition and Quality of Life Outcomes in Adult Cochlear Implant Users: Complementary Contributions of Demographic, Sensory, and Cognitive Factors

HYPOTHESES

Adult cochlear implant (CI) outcomes depend on demographic, sensory, and cognitive factors. However, these factors have not been examined together comprehensively for relations to different outcome types, such as speech recognition versus quality of life (QOL). Three hypotheses were tested: 1) speech recognition will be explained most strongly by sensory factors, whereas QOL will be explained more strongly by cognitive factors. 2) Different speech recognition outcome domains (sentences versus words) and different QOL domains (physical versus social versus psychological functioning) will be explained differentially by demographic, sensory, and cognitive factors. 3) Including cognitive factors as predictors will provide more power to explain outcomes than demographic and sensory predictors alone.

BACKGROUND

A better understanding of the contributors to CI outcomes is needed to prognosticate outcomes before surgery, explain outcomes after surgery, and tailor rehabilitation efforts.

METHODS

Forty-one adult postlingual experienced CI users were assessed for sentence and word recognition, as well as hearing-related QOL, along with a broad collection of predictors. Partial least squares regression was used to identify factors that were most predictive of outcome measures.

RESULTS

Supporting our hypotheses, speech recognition abilities were most strongly dependent on sensory skills, while QOL outcomes required a combination of cognitive, sensory, and demographic predictors. The inclusion of cognitive measures increased the ability to explain outcomes, mainly for QOL.

CONCLUSIONS

Explaining variability in adult CI outcomes requires a broad assessment approach. Identifying the most important predictors depends on the particular outcome domain and even the particular measure of interest.

Healthy aging in elderly cochlear implant recipients: a multinational observational study

Background

Given an increase in the aging population and its impact on healthcare systems, policy makers for provision of health and social services are aiming to keep older adults in good health for longer, in other words towards ‘healthy aging’. Our study objective is to show that rehabilitation with cochlear implant treatment in the elderly with hearing impairment improves the overall health-related quality of life and general well-being that translate into healthy aging.

Methods

The multicentre, prospective, repeated measures, single-subject, clinical observational study will accrue 100 elderly, first-time, unilateral CI recipients (≥ 60 years) and analyze changes on specific measurement tools over ca. 20 months from preimplant to postimplant. Evaluations will consist of details collected through case history and interview questionnaires by clinicians, data logging, self-report questionnaires completed by the recipients and a series of commonly used audiometric measures and geriatric assessment tools. The primary indicator of changes in overall quality of life will be the HUI-3.

Discussion

The protocol is designed to make use of measurement tools that have already been applied to the hearing-impaired population in order to compare effects of CI rehabilitation in adults immediately before their implantation, (pre-implant) and after gaining 1–1.5 years of experience (post-implant). The broad approach will lead to a greater understanding of how useful hearing impacts the quality of life in elderly individuals, and thus improves potentials for healthy aging. Outcomes will be described and analyzed in detail.

Trial registration

This research has been registered in ClinicalTrials.gov (http://www.clinicaltrials.gov/), 7 March 2017 under the n° NCT03072862.

Cognitive Screening of Adults With Postlingual Hearing Loss: A Systematic Review

Objective

To systematically review the evidence for the use of cognitive screening tools for adults with postlingual hearing loss.

Data Sources

PubMed, Embase, Scopus, PsycINFO (EBSCO), CINAHL (EBSCO), and CENTRAL (Cochrane Library) electronic databases were searched from inception until October 4, 2018.

Review Methods

Articles were reviewed for inclusion by 2 independent reviewers. The references of included articles were hand-searched for additional relevant articles. Data were extracted by 2 independent extractors.

Results

Of 2092 articles imported from the search, 81 were included for the review. Nearly a third (31%, n = 25) included patients with profound hearing loss. In total, 23 unique tools were used for 105 unique applications. The Mini Mental Status Exam (MMSE) was the most commonly used (54%, n = 55), followed by the Montreal Cognitive Assessment (MoCA) (19%, n = 10). Nearly half of the tools were used to define patient inclusion or exclusion in a study (48%, n = 50), followed by examination of a change after an intervention (26%, n = 27). Two articles attempted to study the validity of the MMSE and MoCA for screening patients with mild to moderate hearing loss and found mixed effects of the auditory components. There were no validation studies identified from the search.

Conclusion

Many different cognitive screening tools have been used to study patients with postlingual hearing loss. The effects of the auditory components of these tools may be deleterious but ultimately remain unclear from the available evidence. To date, there has been no validation of any cognitive screening tool to be used for adults with postlingual hearing loss.

High- and Low-Performing Adult Cochlear Implant Users on High-Variability Sentence Recognition: Differences in Auditory Spectral Resolution and Neurocognitive Functioning

BACKGROUND

Postlingually deafened adult cochlear implant (CI) users routinely display large individual differences in the ability to recognize and understand speech, especially in adverse listening conditions. Although individual differences have been linked to several sensory (''bottom-up'') and cognitive (''top-down'') factors, little is currently known about the relative contributions of these factors in high- and low-performing CI users.

PURPOSE

The aim of the study was to investigate differences in sensory functioning and neurocognitive functioning between high- and low-performing CI users on the Perceptually Robust English Sentence Test Open-set (PRESTO), a high-variability sentence recognition test containing sentence materials produced by multiple male and female talkers with diverse regional accents.

RESEARCH DESIGN

CI users with accuracy scores in the upper (HiPRESTO) or lower quartiles (LoPRESTO) on PRESTO in quiet completed a battery of behavioral tasks designed to assess spectral resolution and neurocognitive functioning.

STUDY SAMPLE

Twenty-one postlingually deafened adult CI users, with 11 HiPRESTO and 10 LoPRESTO participants.

DATA COLLECTION AND ANALYSIS

A discriminant analysis was carried out to determine the extent to which measures of spectral resolution and neurocognitive functioning discriminate HiPRESTO and LoPRESTO CI users. Auditory spectral resolution was measured using the Spectral-Temporally Modulated Ripple Test (SMRT). Neurocognitive functioning was assessed with visual measures of working memory (digit span), inhibitory control (Stroop), speed of lexical/phonological access (Test of Word Reading Efficiency), and nonverbal reasoning (Raven's Progressive Matrices).

RESULTS

HiPRESTO and LoPRESTO CI users were discriminated primarily by performance on the SMRT and secondarily by the Raven's test. No other neurocognitive measures contributed substantially to the discriminant function.

CONCLUSIONS

High- and low-performing CI users differed by spectral resolution and, to a lesser extent, nonverbal reasoning. These findings suggest that the extreme groups are determined by global factors of richness of sensory information and domain-general, nonverbal intelligence, rather than specific neurocognitive processing operations related to speech perception and spoken word recognition. Thus, although both bottom-up and top-down information contribute to speech recognition performance, low-performing CI users may not be sufficiently able to rely on neurocognitive skills specific to speech recognition to enhance processing of spectrally degraded input in adverse conditions involving high talker variability.

Serial Recall Predicts Vocoded Sentence Recognition Across Spectral Resolutions

Purpose The goal of this study was to determine how various aspects of cognition predict speech recognition ability across different levels of speech vocoding within a single group of listeners. Method We tested the ability of young adults (N = 32) with normal hearing to recognize Perceptually Robust English Sentence Test Open-set (PRESTO) sentences that were degraded with a vocoder to produce different levels of spectral resolution (16, eight, and four carrier channels). Participants also completed tests of cognition (fluid intelligence, short-term memory, and attention), which were used as predictors of sentence recognition. Sentence recognition was compared across vocoder conditions, predictors were correlated with individual differences in sentence recognition, and the relationships between predictors were characterized. Results PRESTO sentence recognition performance declined with a decreasing number of vocoder channels, with no evident floor or ceiling performance in any condition. Individual ability to recognize PRESTO sentences was consistent relative to the group across vocoder conditions. Short-term memory, as measured with serial recall, was a moderate predictor of sentence recognition (ρ = 0.65). Serial recall performance was constant across vocoder conditions when measured with a digit span task. Fluid intelligence was marginally correlated with serial recall, but not sentence recognition. Attentional measures had no discernible relationship to sentence recognition and a marginal relationship with serial recall. Conclusions Verbal serial recall is a substantial predictor of vocoded sentence recognition, and this predictive relationship is independent of spectral resolution. In populations that show variable speech recognition outcomes, such as listeners with cochlear implants, it should be possible to account for the independent effects of spectral resolution and verbal serial recall in their speech recognition ability. Supplemental Material https://doi.org/10.23641/asha.12021051.

Interactions Between Item Set and Vocoding in Serial Recall

OBJECTIVES

Serial recall of digits is frequently used to measure short-term memory span in various listening conditions. However, the use of digits may mask the effect of low quality auditory input. Digits have high frequency and are phonologically distinct relative to one another, so they should be easy to identify even with low quality auditory input. In contrast, larger item sets reduce listener ability to strategically constrain their expectations, which should reduce identification accuracy and increase the time and/or cognitive resources needed for identification when auditory quality is low. This diminished accuracy and increased cognitive load should interfere with memory for sequences of items drawn from large sets. The goal of this work was to determine whether this predicted interaction between auditory quality and stimulus set in short-term memory exists, and if so, whether this interaction is associated with processing speed, vocabulary, or attention.

DESIGN

We compared immediate serial recall within young adults with normal hearing across unprocessed and vocoded listening conditions for multiple stimulus sets. Stimulus sets were lists of digits (1 to 9), consonant-vowel-consonant (CVC) words (chosen from a list of 60 words), and CVC nonwords (chosen from a list of 50 nonwords). Stimuli were unprocessed or vocoded with an eight-channel noise vocoder. To support interpretation of responses, words and nonwords were selected to minimize inclusion of multiple phonemes from within a confusion cluster. We also measured receptive vocabulary (Peabody Picture Vocabulary Test [PPVT-4]), sustained attention (test of variables of attention [TOVA]), and repetition speed for individual items from each stimulus set under both listening conditions.

RESULTS

Vocoding stimuli had no impact on serial recall of digits, but reduced memory span for words and nonwords. This reduction in memory span was attributed to an increase in phonological confusions for nonwords. However, memory span for vocoded word lists remained reduced even after accounting for common phonetic confusions, indicating that lexical status played an additional role across listening conditions. Principal components analysis found two components that explained 84% of the variance in memory span across conditions. Component one had similar load across all conditions, indicating that participants had an underlying memory capacity, which was common to all conditions. Component two was loaded by performance in the vocoded word and nonword conditions, representing the sensitivity of memory span to vocoding of these stimuli. The order in which participants completed listening conditions had a small effect on memory span that could not account for the effect of listening condition. Repetition speed was fastest for digits, slower for words, and slowest for nonwords. On average, vocoding slowed repetition speed for all stimuli, but repetition speed was not predictive of individual memory span. Vocabulary and attention showed no correlation with memory span.

CONCLUSIONS

Our results replicated previous findings that low quality auditory input can impair short-term memory, and demonstrated that this impairment is sensitive to stimulus set. Using multiple stimulus sets in degraded listening conditions can isolate memory capacity (in digit span) from impaired item identification (in word and nonword span), which may help characterize the relationship between memory and speech recognition in difficult listening conditions.

The effect of dopamine on the comprehension of spectrally-shifted noise-vocoded speech: a pilot study

Objectives: Cochlear implantation has proven beneficial in restoring hearing. However, success is variable, and there is a need for a simple post-implantation therapy that could significantly increase implantation success. Dopamine has a general role in learning and in assigning value to environmental stimuli. We tested the effect of dopamine in the comprehension of spectrally-shifted noise-vocoded (SSNV) speech, which simulates, in hearing individuals, the signal delivered by a cochlear implant (CI).Design and study sample: Thirty-five participants (age = 38.0 ± 10.1 SD) recruited from the general population were divided into three groups. We tested SSNV speech comprehension in two experimental sessions. In one session, a metabolic precursor of dopamine (L-DOPA) was administered to participants in two of the groups; a placebo was administered in the other session.Results: A single dose of L-DOPA interacted with training to improve perception of SSNV speech, but did not significantly accelerate learning.Conclusions: These findings are a first step in exploring the use of dopamine to enhance speech understanding in CI patients. Replications of these results using SSNV in individuals with normal hearing, and also in CI users, are needed to determine whether these effects can translate into benefits in everyday language comprehension.

Neurocognitive Factors Contributing to Cochlear Implant Candidacy

HYPOTHESIS

Clinical adult cochlear implant (CI) candidacy evaluations rely heavily on measures of sentence recognition under the best-aided listening conditions. The hypothesis tested in this study was that nonauditory measures of neurocognitive processes would contribute to scores on preoperative sentence recognition for CI candidates, above and beyond hearing ability as assessed using pure-tone average (PTA). Support for this hypothesis would suggest that best-aided sentence recognition is not simply a measure of hearing ability; rather, neurocognitive functions contribute to performance and should be considered while counseling patients during CI candidacy evaluation about postoperative rehabilitative and outcome expectations.

BACKGROUND

Neurocognitive functions, such as working memory capacity, inhibition-concentration, information processing speed, and nonverbal reasoning contribute to aided speech recognition outcomes in adults with hearing loss. This study examined the roles of these neurocognitive factors on preoperative speech recognition performance in adults evaluated for CI candidacy.

METHODS

Thirty-one postlingually deafened adult CI candidates were enrolled. Participants were assessed using nonauditory measures of working memory capacity, inhibition-concentration, information processing speed, and nonverbal reasoning. Measures of sentence recognition in quiet and in multitalker babble (AzBio sentences) as well as sentences from the City University of New York in quiet were collected under best-aided conditions.

RESULTS

AzBio sentence recognition scores in babble were predicted significantly by scores of working memory capacity after accounting for PTA. Similarly, the City University of New York sentence recognition scores were predicted significantly by nonverbal reasoning after accounting for PTA.

CONCLUSIONS

Findings support the idea that clinical measures of sentence recognition may be affected to varying degrees by neurocognitive functions, and these functions should be considered during evaluation for CI candidacy.

Nonverbal Reasoning as a Contributor to Sentence Recognition Outcomes in Adults With Cochlear Implants

HYPOTHESIS

Significant variability in speech recognition persists among postlingually deafened adults with cochlear implants (CIs). We hypothesize that scores of nonverbal reasoning predict sentence recognition in adult CI users.

BACKGROUND

Cognitive functions contribute to speech recognition outcomes in adults with hearing loss. These functions may be particularly important for CI users who must interpret highly degraded speech signals through their devices. This study used a visual measure of reasoning (the ability to solve novel problems), the Raven's Progressive Matrices (RPM), to predict sentence recognition in CI users.

METHODS

Participants were 39 postlingually deafened adults with CIs and 43 age-matched normal-hearing (NH) controls. CI users were assessed for recognition of words in sentences in quiet, and NH controls listened to eight-channel vocoded versions to simulate the degraded signal delivered by a CI. A computerized visual task of the RPM, requiring participants to identify the correct missing piece in a 3×3 matrix of geometric designs, was also performed. Particular items from the RPM were examined for their associations with sentence recognition abilities, and a subset of items on the RPM was tested for the ability to predict degraded sentence recognition in the NH controls.

RESULTS

The overall number of items answered correctly on the 48-item RPM significantly correlated with sentence recognition in CI users (r = 0.35-0.47) and NH controls (r = 0.36-0.57). An abbreviated 12-item version of the RPM was created and performance also correlated with sentence recognition in CI users (r = 0.40-0.48) and NH controls (r = 0.49-0.56).

CONCLUSIONS

Nonverbal reasoning skills correlated with sentence recognition in both CI and NH subjects. Our findings provide further converging evidence that cognitive factors contribute to speech processing by adult CI users and can help explain variability in outcomes. Our abbreviated version of the RPM may serve as a clinically meaningful assessment for predicting sentence recognition outcomes in CI users.

"Product" Versus "Process" Measures in Assessing Speech Recognition Outcomes in Adults With Cochlear Implants

HYPOTHESES

1) When controlling for age in postlingual adult cochlear implant (CI) users, information-processing functions, as assessed using "process" measures of working memory capacity, inhibitory control, information-processing speed, and fluid reasoning, will predict traditional "product" outcome measures of speech recognition. 2) Demographic/audiologic factors, particularly duration of deafness, duration of CI use, degree of residual hearing, and socioeconomic status, will impact performance on underlying information-processing functions, as assessed using process measures.

BACKGROUND

Clinicians and researchers rely heavily on endpoint product measures of accuracy in speech recognition to gauge patient outcomes postoperatively. However, these measures are primarily descriptive and were not designed to assess the underlying core information-processing operations that are used during speech recognition. In contrast, process measures reflect the integrity of elementary core subprocesses that are operative during behavioral tests using complex speech signals.

METHODS

Forty-two experienced adult CI users were tested using three product measures of speech recognition, along with four process measures of working memory capacity, inhibitory control, speed of lexical/phonological access, and nonverbal fluid reasoning. Demographic and audiologic factors were also assessed.

RESULTS

Scores on product measures were associated with core process measures of speed of lexical/phonological access and nonverbal fluid reasoning. After controlling for participant age, demographic and audiologic factors did not correlate with process measure scores.

CONCLUSION

Findings provide support for the important foundational roles of information processing operations in speech recognition outcomes of postlingually deaf patients who have received CIs.

Making Sense of Sentences: Top-Down Processing of Speech by Adult Cochlear Implant Users

Purpose Speech recognition relies upon a listener's successful pairing of the acoustic-phonetic details from the bottom-up input with top-down linguistic processing of the incoming speech stream. When the speech is spectrally degraded, such as through a cochlear implant (CI), this role of top-down processing is poorly understood. This study explored the interactions of top-down processing, specifically the use of semantic context during sentence recognition, and the relative contributions of different neurocognitive functions during speech recognition in adult CI users. Method Data from 41 experienced adult CI users were collected and used in analyses. Participants were tested for recognition and immediate repetition of speech materials in the clear. They were asked to repeat 2 sets of sentence materials, 1 that was semantically meaningful and 1 that was syntactically appropriate but semantically anomalous. Participants also were tested on 4 visual measures of neurocognitive functioning to assess working memory capacity (Digit Span; Wechsler, 2004), speed of lexical access (Test of Word Reading Efficiency; Torgeson, Wagner, & Rashotte, 1999), inhibitory control (Stroop; Stroop, 1935), and nonverbal fluid reasoning (Raven's Progressive Matrices; Raven, 2000). Results Individual listeners' inhibitory control predicted recognition of meaningful sentences when controlling for performance on anomalous sentences, our proxy for the quality of the bottom-up input. Additionally, speed of lexical access and nonverbal reasoning predicted recognition of anomalous sentences. Conclusions Findings from this study identified inhibitory control as a potential mechanism at work when listeners make use of semantic context during sentence recognition. Moreover, speed of lexical access and nonverbal reasoning were associated with recognition of sentences that lacked semantic context. These results motivate the development of improved comprehensive rehabilitative approaches for adult patients with CIs to optimize use of top-down processing and underlying core neurocognitive functions.

How Does Nonverbal Reasoning Affect Sentence Recognition in Adults with Cochlear Implants and Normal-Hearing Peers?

BACKGROUND

Previous research has demonstrated an association of scores on a visual test of nonverbal reasoning, Raven's Progressive Matrices (RPM), with scores on open-set sentence recognition in quiet for adult cochlear implant (CI) users as well as for adults with normal hearing (NH) listening to noise-vocoded sentence materials. Moreover, in that study, CI users demonstrated poorer nonverbal reasoning when compared with NH peers. However, it remains unclear what underlying neurocognitive processes contributed to the association of nonverbal reasoning scores with sentence recognition, and to the poorer scores demonstrated by CI users.

OBJECTIVES

Three hypotheses were tested: (1) nonverbal reasoning abilities of adult CI users and normal-hearing (NH) age-matched peers would be predicted by performance on more basic neurocognitive measures of working memory capacity, information-processing speed, inhibitory control, and concentration; (2) nonverbal reasoning would mediate the effects of more basic neurocognitive functions on sentence recognition in both groups; and (3) group differences in more basic neurocognitive functions would explain the group differences previously demonstrated in nonverbal reasoning.

METHOD

Eighty-three participants (40 CI and 43 NH) underwent testing of sentence recognition using two sets of sentence materials: sentences produced by a single male talker (Harvard sentences) and high-variability sentences produced by multiple talkers (Perceptually Robust English Sentence Test Open-set, PRESTO). Participants also completed testing of nonverbal reasoning using a visual computerized RPM test, and additional neurocognitive assessments were collected using a visual Digit Span test and a Stroop Color-Word task. Multivariate regression analyses were performed to test our hypotheses while treating age as a covariate.

RESULTS

In the CI group, information processing speed on the Stroop task predicted RPM performance, and RPM scores mediated the effects of information processing speed on sentence recognition abilities for both Harvard and PRESTO sentences. In contrast, for the NH group, Stroop inhibitory control predicted RPM performance, and a trend was seen towards RPM scores mediating the effects of inhibitory control on sentence recognition, but only for PRESTO sentences. Poorer RPM performance in CI users than NH controls could be partially attributed to slower information processing speed.

CONCLUSIONS

Neurocognitive functions contributed differentially to nonverbal reasoning performance in CI users as compared with NH peers, and nonverbal reasoning appeared to partially mediate the effects of these different neurocognitive functions on sentence recognition in both groups, at least for PRESTO sentences. Slower information processing speed accounted for poorer nonverbal reasoning scores in CI users. Thus, it may be that prolonged auditory deprivation contributes to cognitive decline through slower information processing.

How does aging affect recognition of spectrally degraded speech?

OBJECTIVES/HYPOTHESIS

Cochlear implants (CIs) restore auditory sensation to patients with moderate-to-profound sensorineural hearing loss. However, the benefits to speech recognition vary considerably among patients. Advancing age contributes to this variability in postlingual adult CI users. Similarly, older individuals with normal hearing (NH) perform more poorly on tasks of recognition of spectrally degraded speech. The overarching hypothesis of this study was that the detrimental effects of advancing age on speech recognition can be attributed both to declines in auditory spectral resolution as well as declines in cognitive functions.

STUDY DESIGN

Case-control study.

METHODS

Speech recognition was assessed in CI users (in the clear) and NH controls (spectrally degraded using noise-vocoding), along with auditory spectral resolution using the Spectral-Temporally Modulated Ripple Test. Cognitive skills were assessed using nonauditory visual measures of working memory, inhibitory control, speed of lexical/phonological access, nonverbal reasoning, and perceptual closure. Linear regression models were tested for mediation to explain aging effects on speech recognition performance.

RESULTS

For both groups, older age predicted poorer sentence and word recognition. The detrimental effects of advancing age on speech recognition were partially mediated by declines in spectral resolution and in some measures of cognitive function.

CONCLUSIONS

Advancing age contributes to poorer recognition of degraded speech for CI users and NH controls through declines in both auditory spectral resolution and cognitive functions. Findings suggest that improvements in spectral resolution as well as cognitive improvements may serve as therapeutic targets to optimize CI speech recognition outcomes.

LEVEL OF EVIDENCE

3b Laryngoscope, 2018.

What to Do When Cochlear Implant Users Plateau in Performance: a Pilot Study of Clinician-guided Aural Rehabilitation

HYPOTHESIS

For experienced adult cochlear implant (CI) users who have reached a plateau in performance, a clinician-guided aural rehabilitation (CGAR) approach can improve speech recognition and hearing-related quality of life (QOL).

BACKGROUND

A substantial number of CI users do not reach optimal performance in terms of speech recognition ability and/or personal communication goals. Although self-guided computerized auditory training programs have grown in popularity, compliance and efficacy for these programs are poor. We propose that CGAR can improve speech recognition and hearing-related QOL in experienced CI users.

METHODS

Twelve adult CI users were enrolled in an 8-week CGAR program guided by a speech-language pathologist and audiologist. Nine patients completed the program along with pre-AR and immediate post-AR testing of speech recognition (AzBio sentences in quiet and in multitalker babble, Consonant-Nucleus-Consonant words in quiet), QOL (Nijmegen Cochlear Implant Questionnaire, Hearing Handicap Inventory for Adults/Elderly, and Speech, Spatial and Qualities of Hearing Scale), and neurocognitive functioning (working memory capacity, information-processing speed, inhibitory control, speed of lexical/phonological access, and nonverbal reasoning). Pilot data for these nine patients are presented.

RESULTS

From pre-CGAR to post-CGAR, group mean improvements in word recognition were found. Improvements were also demonstrated on some composite and subscale measures of QOL. Patients who demonstrated improvements in word recognition were those who performed most poorly at baseline.

CONCLUSIONS

CGAR represents a potentially efficacious approach to improving speech recognition and QOL for experienced CI users. Limitations and considerations in implementing and studying aural rehabilitation approaches are discussed.

Relations Between Self-reported Executive Functioning and Speech Perception Skills in Adult Cochlear Implant Users

HYPOTHESIS

As a result of their hearing loss, adults with cochlear implants (CIs) would self-report poorer executive functioning (EF) skills than normal-hearing (NH) peers, and these EF skills would be associated with performance on speech recognition tasks.

BACKGROUND

EF refers to a group of high order neurocognitive skills responsible for behavioral and emotional regulation during goal-directed activity, and EF has been found to be poorer in children with CIs than their NH age-matched peers. Moreover, there is increasing evidence that neurocognitive skills, including some EF skills, contribute to the ability to recognize speech through a CI.

METHODS

Thirty postlingually deafened adults with CIs and 42 age-matched NH adults were enrolled. Participants and their spouses or significant others (informants) completed well-validated self-reports or informant-reports of EF, the Behavior Rating Inventory of Executive Function - Adult (BRIEF-A). CI users' speech recognition skills were assessed in quiet using several measures of sentence recognition. NH peers were tested for recognition of noise-vocoded versions of the same speech stimuli.

RESULTS

CI users self-reported difficulty on EF tasks of shifting and task monitoring. In CI users, measures of speech recognition correlated with several self-reported EF skills.

CONCLUSION

The present findings provide further evidence that neurocognitive factors, including specific EF skills, may decline in association with hearing loss, and that some of these EF skills contribute to speech processing under degraded listening conditions.

Visual working memory span in adults with cochlear implants: Some preliminary findings

Objective

Neurocognitive functions, specifically verbal working memory (WM), contribute to speech recognition in postlingual adults with cochlear implants (CIs) and normal-hearing (NH) listener shearing degraded speech. Three hypotheses were tested: (1) WM accuracy as assessed using three visual span measures - digits, objects, and symbols - would correlate with recognition scores for spectrally degraded speech (through a CI or when noise-vocoded); (2) WM accuracy would be best for digit span, intermediate for object span, and lowest for symbol span, due to the increasing cognitive demands across these tasks. Likewise, response times, relating to processing demands, would be shortest for digit span, intermediate for object span, and longest for symbol span; (3) CI users would demonstrate poorer and slower performance than NH peers on WM tasks, as a result of less efficient verbally mediated encoding strategies associated with a period of prolonged auditory deprivation.

Methods

Cross-sectional study of 30 postlingually deaf adults with CIs and 34 NH controls. Participants were tested for sentence recognition in quiet (CI users) or after noise-vocoding (NH peers), along with WM using visual measures of digit span, object span, and symbol span.

Results

Of the three measures of WM, digit span scores alone correlated with sentence recognition for CI users; no correlations were found using these three measures for NH peers. As predicted, WM accuracy (and response times) were best (and fastest) for digit span, intermediate for object span, and worst (and slowest) for symbol span. CI users and NH peers demonstrated equivalent WM accuracy and response time for digit span and object span, and similar response times for symbol span, but contrary to our original predictions, CI users demonstrated better accuracy on symbol span than NH peers.

Conclusions

Verbal WM assessed using visual tasks relates weakly to sentence recognition for degraded speech. CI users performed equivalently to NH peers on most visual tasks of WM, but they outperformed NH peers on symbol span accuracy. This finding deserves further exploration but may suggest that CI users develop alternative or compensatory strategies associated with rapid verbal coding, as a result of their prolonged experience of auditory deprivation.

Relating quality of life to outcomes and predictors in adult cochlear implant users: Are we measuring the right things?

OBJECTIVE

Current clinical outcome measures for adults receiving cochlear implants (CIs) consist of word and sentence recognition, primarily under quiet conditions. However, these measures may not adequately reflect patients' CI-specific quality of life (QOL). This study first examined traditional auditory-only speech recognition measures and other potentially relevant auditory measures as correlates of QOL in CI users. Second, scores on nonauditory tasks of language and cognition were examined as potential predictors of QOL.

STUDY DESIGN

Twenty-five postlingually deafened adults with CIs were assessed.

METHODS

Participants completed a validated CI-specific QOL measure (the Nijmegen Cochlear Implant Questionnaire) and were tested for word and sentence recognition in quiet, as well as sentence recognition in speech-shaped noise. Participants also completed assessments of audiovisual speech recognition, environmental sound identification, and a task of complex auditory verbal processing. Several nonauditory language and cognitive tasks were examined as potential predictors of QOL.

RESULTS

Quality-of-life scores significantly correlated with scores for audiovisual speech recognition and recognition of complex sentences in quiet but not sentences in noise or isolated words. No significant correlations were obtained between QOL and environmental sound identification or complex auditory verbal processing. Quality-of-life subdomain scores were predicted by several nonauditory language and cognitive tasks as well as some patient characteristics.

CONCLUSION

Postoperative measures of recognition of sentences in quiet and audiovisual sentence recognition correlate with CI-related QOL. Findings suggest that sentence recognition tasks are QOL-relevant outcomes but only explain a small fraction of the variability in QOL outcomes for this patient population.

LEVEL OF EVIDENCE

4. Laryngoscope, 128:959-966, 2018.

Verbal working memory and inhibition-concentration in adults with cochlear implants

Objectives

Neurocognitive functions contribute to speech recognition in postlingual adults with cochlear implants (CIs). In particular, better verbal working memory (WM) on modality‐specific (auditory) WM tasks predicts better speech recognition. It remains unclear, however, whether this association can be attributed to basic underlying modality‐general neurocognitive functions, or whether it is solely a result of the degraded nature of auditory signals delivered by the CI. Three hypotheses were tested: 1) Both modality‐specific and modality‐general tasks of verbal WM would predict scores of sentence recognition in speech‐shaped noise; 2) Basic modality‐general neurocognitive functions of controlled fluency and inhibition‐concentration would predict both modality‐specific and modality‐general verbal WM; and 3) Scores on both tasks of verbal WM would mediate the effects of more basic neurocognitive functions on sentence recognition.

Study Design

Cross‐sectional study of 30 postlingual adults with CIs and thirty age‐matched normal‐hearing (NH) controls.

Materials and Methods

Participants were tested for sentence recognition in speech‐shaped noise, along with verbal WM using a modality‐general task (Reading Span) and an auditory modality‐specific task (Listening Span). Participants were also assessed for controlled fluency and inhibition‐concentration abilities.

Results

For CI users only, Listening Span scores predicted sentence recognition, and Listening Span scores mediated the effects of inhibition‐concentration on speech recognition. Scores on Reading Span were not related to sentence recognition for either group.

Conclusion

Inhibition‐concentration skills play an important role in CI users' sentence recognition skills, with effects mediated by modality‐specific verbal WM. Further studies will examine inhibition‐concentration and WM skills as novel targets for clinical intervention.

Level of Evidence

4.