Listening Effort and Memory Effort in Cochlear Implant Users: A Pupillometry Study.

The pupil dilation response is often used as a physiological measure of listening effort. One way to manipulate listening effort is to manipulate intelligibility. Only a few studies assessed the relationship between intelligibility and the pupil dilation response in cochlear implant (CI) users. Those studies did not consistently replicate the effects of intelligibility on the pupil dilation response evoked by sentence recognition in noise as observed in individuals with typical hearing or hard of hearing. Therefore, this study examined the effects of intelligibility on the pupil dilation response in CI users using several types of speech material. The type of masker is also known to influence listening effort as measured by pupillometry in individuals with typical hearing and hard of hearing. To our knowledge, this is not yet investigated in CI users. Therefore, this was also assessed in the current study. Finally, to account for subjective experiences, ratings of listening effort, difficulty, performance, and tendency of giving up were assessed. Twenty-eight postlingually deafened adult unilateral or bimodal CI users participated. Their ages ranged from 41 to 71 yrs old (mean = 58.4). A 3 × 3 within-subjects design was used with 3 intelligibility conditions (quiet, 50%, and 20% intelligibility in continuous noise) and 3 types of speech material (digit triplets, consonant-vowel-consonant [CVC] words, everyday sentences). Linear mixed model analyses assessed the effects of speech material and intelligibility condition on the mean pupil dilation (MPD), peak pupil dilation (PPD), and baseline pupil size (BPS). A paired sample t test was used to compare the effect of masker type (continuous noise versus a single interfering speaker) on these pupil measures for 50% sentence intelligibility. For all conditions, participants rated their experienced listening effort, difficulty, performance, and tendency of giving up. In the main analysis (N = 23), MPD, PPD, and BPS differed between the speech materials, but these measures did not depend on speech intelligibility. CVC words elicited the lowest MPDs and PPDs, followed by digit triplets and everyday sentences, with the latter showing the most pronounced pupil responses. The BPS was larger for sentences compared with CVC words and digit triplets. CVC words and sentences were rated as the most effortful and difficult, with the lowest self-perceived performance, and evoking the highest tendency to give up. Self-perceived performance was furthermore influenced by intelligibility (quiet > 50% > 20%). The other subjective ratings, such as listening effort, decreased with increasing intelligibility. A separate analysis on the data for the digit triplet material, including all CI users (n = 28), showed an intelligibility effect on the PPD. Finally, the analysis (N = 15) of the effect of masker type showed that PPDs and BPSs were larger for sentences masked with an interfering speaker compared with continuous noise. The intelligibility conditions in this study did not result in any measurable differences in listening effort, as indicated by the pupil dilation responses of unilateral or bimodal postlingually deafened CI users for everyday sentences or CVC words. A main effect of intelligibility condition on PPD was only found for digit triplets. Speculatively, this may be because the relative simplicity and low cognitive load evoked by this speech material allowed intelligibility effects to become apparent in this specific group of listeners. Subjective ratings indicated greater listening effort, difficulty, and a tendency to give up at lower intelligibility levels. When sentences were masked with an interfering speaker, both PPD and subjective listening effort increased compared with masking with continuous noise. These findings suggest that manipulating masker type can alter the pupil dilation response and perceived listening effort in CI users, even when using everyday sentences.

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An intact auditory system is essential for the development and maintenance of voice quality and speech prosody. On the contrary hearing loss affects the adjustments and appropriate use of organs involved in speech and voice production. Spectro-acoustic voice parameters have been evaluated in Cochlear Implant (CI) users, and the authors of previous systematic reviews on the topic concluded that fundamental frequency (F0) seemed preliminarily the most reliable parameter to evaluate voice alterations in adult CI users. The main aim of this systematic review and meta-analysis was to clarify the vocal parameters and prosodic alterations of speech in pediatric CI users. The protocol of the systematic review was registered on the PROSPERO database, International prospective register of systematic reviews. We conducted a search of the English literature published in the period between January 1, 2005 and April 1, 2022 on the Pubmed and Scopus databases. A meta-analysis was conducted to compare the values of voice acoustic parameters in CI users and non-hearing-impaired controls. The analysis was conducted using the standardized mean difference as the outcome measure. A random-effects model was fitted to the data. A total of 1334 articles were initially evaluated using title and abstract screening. After applying inclusion/exclusion criteria, 20 articles were considered suitable for this review. The age of the cases ranged between 25 and 132 months at examination. The most studied parameters were F0, Jitter, Shimmer and Harmonics-to-Noise Ratio (HNR); other parameters were seldom reported. A total of 11 studies were included in the meta-analysis of F0, with the majority of estimates being positive (75%); the estimated average standardized mean difference based on the random-effects model was 0.3033 (95% CI: 0.0605 to 0.5462; P = 0.0144). For Jitter (0.2229; 95% CI: -0.1862 to 0.7986; P = 0.2229) and shimmer (0.2540; 95% CI: -0.1404 to 0.6485; P = 0.2068) there was a trend toward positive values without reaching statistical significance. This meta-analysis confirmed that higher F0 values have been observed in the pediatric population of CI users compared to age-matched normal hearing volunteers, whereas the parameters of voice noise were not significantly different between cases and controls. Prosodic aspects of language need further investigations. In longitudinal contexts, prolonged auditory experience with CI has brought voice parameters closer to the norm. Following the available evidence, we stress the utility of inclusion of vocal acoustic analysis in the clinical evaluation and follow-up of CI patients to optimize the rehabilitation process of pediatric patients with hearing loss.

On the relationship between auditory cognition and speech intelligibility in cochlear implant users: An ERP study

Cochlear implantation constitutes a successful therapy of inner ear deafness, with the majority of patients showing good outcomes. There is, however, still some unexplained variability in outcomes with a number of cochlear-implant (CI) users, showing major limitations in speech comprehension. The current study used a multimodal diagnostic approach combining single-photon emission computed tomography (SPECT) and electroencephalography (EEG) to examine the mechanisms underlying speech processing in postlingually deafened CI users (N = 21). In one session, the participants performed a speech discrimination task, during which a 96-channel EEG was recorded and the perfusions marker 99mTc-HMPAO was injected intravenously. The SPECT scan was acquired 1.5 h after injection to measure the cortical activity during the speech task. The second session included a SPECT scan after injection without stimulation at rest. Analysis of EEG and SPECT data showed N400 and P600 event-related potentials (ERPs) particularly evoked by semantic violations in the sentences, and enhanced perfusion in a temporo-frontal network during task compared to rest, involving the auditory cortex bilaterally and Broca’s area. Moreover, higher performance in testing for word recognition and verbal intelligence strongly correlated to the activation in this network during the speech task. However, comparing CI users with lower and higher speech intelligibility [median split with cutoff + 7.6 dB signal-to-noise ratio (SNR) in the Göttinger sentence test] revealed for CI users with higher performance additional activations of parietal and occipital regions and for those with lower performance stronger activation of superior frontal areas. Furthermore, SPECT activity was tightly coupled with EEG and cognitive abilities, as indicated by correlations between (1) cortical activation and the amplitudes in EEG, N400 (temporal and occipital areas)/P600 (parietal and occipital areas) and (2) between cortical activation in left-sided temporal and bilateral occipital/parietal areas and working memory capacity. These results suggest the recruitment of a temporo-frontal network in CI users during speech processing and a close connection between ERP effects and cortical activation in CI users. The observed differences in speech-evoked cortical activation patterns for CI users with higher and lower speech intelligibility suggest distinct processing strategies during speech rehabilitation with CI.

Background: Pupil dilation, a measure of physiological arousal, is associated with increased cognitive demand (Moresi et al, 2008) and response preparation in the antisaccade task. Greater change in pupil size during the preparatory period prior to saccade generation for correctly performed antisaccade trials vs prosaccade errors has been observed among healthy controls, perhaps reflecting inhibitory input from the frontal eye fields (FEF) and superior colliculus (SC) to brainstem regions responsible for saccade generation (Wang et al, 2015). The relationship between pupillary response and antisaccade performance in individuals across the psychosis spectrum is less established. Our objective was to examine differences in the relationship between changes in pupil size during the preparatory period and antisaccade performance in individuals across the psychosis spectrum and healthy controls.

Objective To investigate electrically evoked auditory cortical responses (eACR) elicited from the stimulation of intracochlear electrodes based on individually fitted stimulation parameters in cochlear implant (CI) users. Design An eACR setup based on individual fitting parameters is proposed. A 50-ms alternating biphasic pulse train was used to stimulate apical, medial, and basal electrodes and to evoke auditory cortical potentials (N1-P2 complex). Study sample The eACR setup proposed was validated with 14 adult CI users. Results Individual and grand-average eACR waveforms were obtained. The eACR amplitudes were lower in the basal than in the apical and medial regions. Earlier N1 latencies were found in CI users with lower maximum comfortable loudness levels and shorter phase duration in response to apical stimulation, while medial and basal stimulation resulted in earlier N1 latencies and larger N1-P2 amplitudes in users with longer CI experience. Conclusions eACR could be elicited by direct intracochlear stimulation using individual fitting parameters with a success rate of 71%. The highest cortical peak-to-peak amplitudes were obtained in response to apical stimulation. Unlike the P2, the N1 component appeared to be a consistent cortical potential to determine eACR and gain knowledge of the auditory processing beyond the cochlea in CI users. Highlights eACR can be elicited through direct stimulation of intracochlear electrodes. Stimulation of apical and medial regions yielded the highest N1-P2 amplitudes. CI users with lower maximum comfortable loudness levels had shorter N1 latencies during apical stimulation. The present dataset of mainly well-performing CI users suggests better cortical processing, that is, higher amplitudes and shorter latencies of N1. The N1 potential appears a more consistent and reliable potential than the P2 to determine eACR responses in CI users.

ABSTRACTNormal auditory feedback contributes to moment-to-moment control of speech production. Effects of auditory feedback’s absence on hearing-impaired individuals are widely documented, but auditory perturbation has not been investigated. Our objective was to evaluate the effect of delayed auditory feedback (DAF) and frequency altered feedback (FAF) on speech production among prelingual cochlear implant (CI) users and normal hearing (NH) individuals, to evaluate CI users’ reliance on auditory feedback. Twenty young adults (10 CI, 10 NH), without developmental and cognitive impairments, participated in the study. Under variable auditory feedback conditions, speech production (spontaneous or reading aloud) was measured using speech rate, percentage of interruptions, fundamental frequency (F0), and relative intensity. Results showed that (1) both DAF and FAF caused slower speech rates and more interruptions while reading aloud, with DAF having larger effect; (2) altered feedback produced no differences between groups, except an increase in F0 for CI users during DAF; and (3) CI users’ ability to understand speech via phone and without lip-reading was positively correlated with performance under DAF. These findings suggest that auditory perturbation similarly affects speech production among prelingual CI users and NH individuals, indicating CI users depend on auditory feedback to the same degree as normal hearing individuals.

A cochlear implant (CI) is a hearing device introduced in the 1980s for profoundly deaf subjects who gained little or no benefit from powerful hearing aids. This device comprises an electrode array inserted in the cochlea, connected to an internal receiver, and an externally worn speech processor. The CI transforms acoustic signals into electrical currents which directly stimulate the auditory nerve. Since the early 1990s, cochlear implantation in children has been developing rapidly. Although it is still difficult to predict how a child will perform with a cochlear implant, the success of cochlear implantation can no longer be denied. In this paper, some recent papers and reports, and the results of the various Nijmegen cochlear implant studies, are reviewed. Issues about selection, examinations, surgery and the outcome are discussed. Overall, our results were comparable with those of other authors. It can be concluded that cochlear implantation is an effective treatment for postlingually deaf as well as prelingually (congenital or acquired) deaf children with profound bilateral sensorineural deafness.

Musical and vocal emotion perception for cochlear implants users

Some cochlear implant (CI) users report having difficulty accessing indexical information in the speech signal, presumably due to limitations in the transmission of fine spectrotemporal cues. The purpose of this review article was to systematically review and evaluate the existing research on talker processing in CI users. Specifically, we reviewed the performance of CI users in three types of talker- and voice-related tasks. We also examined the different factors (such as participant, hearing, and device characteristics) that might influence performance in these specific tasks. We completed a systematic search of the literature with select key words using citation aggregation software to search Google Scholar. We included primary reports that tested (a) talker discrimination, (b) voice perception, and (c) talker identification. Each report must have had at least one group of participants with CIs. Each included study was also evaluated for quality of evidence. The searches resulted in 1,561 references, which were first screened for inclusion and then evaluated in full. Forty-three studies examining talker discrimination, voice perception, and talker identification were included in the final review. Most studies were focused on postlingually deafened and implanted adult CI users, with fewer studies focused on prelingual implant users. In general, CI users performed above chance in these tasks. When there was a difference between groups, CI users performed less accurately than their normal-hearing (NH) peers. A subset of CI users reached the same level of performance as NH participants exposed to noise-vocoded stimuli. Some studies found that CI users and NH participants relied on different cues for talker perception. Within groups of CI users, there is moderate evidence for a bimodal benefit for talker processing, and there are mixed findings about the effects of hearing experience. The current review highlights the challenges faced by CI users in tracking and recognizing voices and how they adapt to it. Although large variability exists, there is evidence that CI users can process indexical information from speech, though with less accuracy than their NH peers. Recent work has described some of the factors that might ease the challenges of talker processing in CI users. We conclude by suggesting some future avenues of research to optimize real-world speech outcomes.

Aging may limit speech understanding outcomes in cochlear-implant (CI) users.Here, we examined age-related declines in auditory temporal processing as apotential mechanism that underlies speech understanding deficits associated withaging in CI users. Auditory temporal processing was assessed with acategorization task for the words dish and ditch (i.e., identify each token asthe word dish or ditch) on a continuum ofspeech tokens with varying silence duration (0 to 60 ms) prior to the finalfricative. In Experiments 1 and 2, younger CI (YCI), middle-aged CI (MCI), andolder CI (OCI) users participated in the categorization task across a range ofpresentation levels (25 to 85 dB). Relative to YCI, OCI required longer silencedurations to identify ditch and exhibited reduced ability to distinguish thewords dish and ditch (shallower slopes in the categorization function).Critically, we observed age-related performance differences only at higherpresentation levels. This contrasted with findings from normal-hearing listenersin Experiment 3 that demonstrated age-related performance differencesindependent of presentation level. In summary, aging in CI users appears todegrade the ability to utilize brief temporal cues in word identification,particularly at high levels. Age-specific CI programming may potentially improveclinical outcomes for speech understanding performance by older CIlisteners.

Early attachment relationships exert lasting effects on psychophysical health across the lifespan. Limited behavioral evidence suggests that these effects stem from how individuals perceive, interpret, and respond to their environment. This study investigated whether adults’ attachment representations modulate autonomic responses to happy and sad facial expressions, evidenced by changes in pupil size. We utilized a sample of healthy adults (N = 100; 68% females, 18–35 years, prevalently White European). In an eye-tracking experiment, we assessed pupil dilation to happy and sad facial expressions (n = 152 trials). Dismissing and preoccupied attachment orientations were assessed as continuous dimensions via self-report. Linear mixed models revealed that individuals with higher scores on dismissing orientations exhibited a significant increase in pupil dilation in response to sad and not happy expressions. No significant effects were observed for preoccupied orientations, age, or sex. These findings suggest that individuals with increased scores on dismissing attachment show heightened arousal to negative emotions.

Figure: © iStock/chaossCochlear implants (CIs) have allowed users to understand speech and interact with the auditory world. However, CI recipients still have difficulty perceiving nonspeech sounds, especially music. Music appreciation is important to evaluate in CI users because of its association with quality of life, personal expression, and social connectedness.Figure: Alice HeCochlear implant recipients have difficulty recognizing musical melodies, identifying instrument sounds, and differentiating pitch. However, perceptual accuracy is not the only important aspect in music listening. The way music sounds as a whole through the cochlear implant has clinical relevance, as it relates to the user's ability to appreciate and enjoy music in everyday life.Figure: Charles J. Limb, MDWhile one might anticipate a direct link between cochlear implant recipients’ ability to perceive music accurately and their degree of music appreciation, the early literature has not supported this idea. In fact, some studies suggest exactly the opposite—that there is little to no relationship between music perception and appraisal in CI users ( J Am Acad Audiol 2012;23[5]:350-365http://aaa.publisher.ingentaconnect.com/content/aaa/jaaa/2012/00000023/00000005/art00006). However, these previous results were obtained from small cohorts of cochlear implant recipients in controlled laboratory settings, with tests that require significant time to administer, limiting their applicability in clinical settings. In a new study, Ward R. Drennan, PhD, and colleagues evaluated the correlation between music perception and appraisal among a large cohort of CI users in clinical settings. The authors used shorter music tests to determine if these assessments could be administered in the clinic and whether findings would be consistent with previous results from smaller sample sizes. Clinical Evaluation of Music Perception, Appraisal, and Experience in Cochlear Implant Users Drennan WR, Oleson JJ, Gfeller K, et al Int J Audiol Sept. 1, 2014; e-pub ahead of printhttp://informahealthcare.com/doi/abs/10.3109/14992027.2014.948219 The Clinical Assessment of Music Perception (CAMP) test is commonly used in some laboratories to study CI users’ music perception ( Otol Neurotol 2008;29[2]:149-155http://journals.lww.com/otology-neurotology/Abstract/2008/02000/Clinical_Assessment_of_Music_Perception_in.10.aspx; Ear Hear 2009;30[4]:411-418http://journals.lww.com/ear-hearing/Abstract/2009/08000/Development_and_Validation_of_the_University_of.4.aspx). The CAMP includes three separate perception tests, each designed to evaluate a different element of music perception ability: pitch direction discrimination, familiar melody recognition, and timbre recognition. Since these three elements are relevant to music listening and enjoyment, Dr. Drennan et al used the CAMP test to study music perception. To assess music appraisal, the researchers used the Iowa Musical Background Questionnaire (IMBQ). In the IMBQ, CI recipients described the quality of music heard through their cochlear implant by rating six bipolar adjectives on a scale of zero to 10: clear versus fuzzy, easy to follow versus difficult to follow, like versus dislike, sounds unlike music versus sounds like music, unnatural versus natural, and unpleasant versus pleasant. Prior research identified these comparisons as relevant to music listening. The CAMP test and IMBQ were administered to 145 CI listeners across 14 clinical sites in the United States and Canada. It took 30 minutes to 35 minutes to administer the CAMP test, and another 15 minutes to 25 minutes to complete the IMBQ. These time frames are reasonable for administration in the clinic—a major advantage in terms of practical feasibility, the authors noted. WEAK RELATIONSHIP REPORTED In their group of cochlear implant users from several clinical settings, Dr. Drennan and colleagues found weak relationships between CAMP results and IMBQ musical sound quality scores. There was a statistically significant but slight correlation between the CAMP's timbre test component and music appraisal, suggesting a relatively weak association between the two. All other relationships were deemed insignificant. This lack of a strong association, which is consistent with the findings of previous studies ( J Am Acad Audiol 2012;23[5]:350-365http://aaa.publisher.ingentaconnect.com/content/aaa/jaaa/2012/00000023/00000005/art00006; J Am Acad Audiol 2008;19[2]:120-134http://aaa.publisher.ingentaconnect.com/content/aaa/jaaa/2008/00000019/00000002/art00003) means that in order to fully evaluate CI music functionality, it is not sufficient to test either music perception or music appraisal alone. Both measures need to be evaluated, as sufficiency or deficiency in one aspect does not correlate with the same result in the other aspect. These results also highlight the limitations of subjective musical sound quality assessment and the possible benefits of objective approaches ( Otol Neurotol 2012;33[3]:319-327http://journals.lww.com/otology-neurotology/Abstract/2012/04000/Assessment_of_Sound_Quality_Perception_in_Cochlear.7.aspx). In an objective approach, the goal is not to evaluate how pleasant or unpleasant music may sound, or whether the CI user enjoys it. Rather, the goal is to measure the capacity of a cochlear implant user to detect a deterioration of sound quality in response to experimental manipulation of any given sound parameter. MANY FACTORS AFFECT ENJOYMENT Dr. Drennan and colleagues noted limitations of their study design. For example, the CAMP was conducted without hearing aids, even if listeners used hearing aids regularly. While the IMBQ questionnaire asked about music appraisal based on real-world musical listening experiences, the CAMP used simple, controlled sound stimuli to assess basic music perception abilities instead of using real-world stimuli. To some extent, these study design decisions might have affected CI users’ music test scores. Despite these potential limitations, the authors make a compelling argument that perceptual acuity is not closely related to music appraisal ratings. In other words, cochlear implant users can have poor perceptual abilities and still feel that music sounds good or is highly enjoyable. Conversely, CI users can perceive various aspects of music well while feeling that music sounds poor or not enjoying what they are able to hear. The study by Dr. Drennan and colleagues underscores the notion that the musical experience is linked to many factors. Furthermore, these findings suggest that studying individual elements of music in isolation may not accurately reflect the perceptual salience of music when it's presented in its natural form—a composite of a wide range of components. In this study, the authors demonstrated that there is little to no relationship between music acuity and music appraisal. Both aspects are important clinical outcomes, as one addresses patient functionality and ability (acuity), while the other addresses patient feeling and overall satisfaction with music quality (appraisal). These findings strongly suggest the need for further research to overcome limitations in cochlear implant users’ ability to perceive music, and to understand the factors that limit enjoyment or satisfaction in music listening.

Eye-tracking methodologies have revealed that eye movements and pupil dilations are influenced by our previous experiences. Dynamic fluctuations in pupil size during learning reflect in part the formation of memories for learned information, while viewing behavior during memory testing is influenced by memory retrieval and drawn to previously learned associations. However, no study to date has linked fluctuations in pupil dilation at encoding to the magnitude of viewing behavior at test. The current investigation involved monitoring eye movements both in single item recognition and relational recognition tasks. In the item task, all faces were presented with the same background scene and memory for faces was subsequently tested, whereas in the relational task each face was presented with its own unique background scene and memory for the face-scene association was subsequently tested. Pupil size changes during encoding predicted the magnitude of preferential viewing during test, as well as future recognition accuracy. These effects emerged only in the relational task, but not in the item task, and were replicated in an additional experiment in which stimulus luminance was more tightly controlled. A follow-up experiment and additional analyses ruled out differences in orienting instructions or number of fixations to the encoding display as explanations of the observed effects. The results shed light on the links between pupil dilation, memory encoding, and eye movement patterns during recognition and suggest that trial-level fluctuations in pupil dilation during encoding reflect relational binding of items to their context rather than general memory formation or strength. (PsycInfo Database Record (c) 2024 APA, all rights reserved).