Hearing Loss and Cognitive Decline in the Aging Population: Emerging Perspectives in Audiology.

In this perspective article, the author explores the connections between hearing loss, central auditory processing, and cognitive decline, offering insights into the complex dynamics at play. Drawing upon a range of studies, the relationship between age-related central auditory processing disorders and Alzheimer's disease is discussed, with the aim of enhancing our understanding of these interconnected conditions. Highlighting the evolving significance of audiologists in the dual management of cognitive health and hearing impairments, the author focuses on their role in identifying early signs of cognitive impairment and evaluates various cognitive screening tools used in this context. The discussion extends to adaptations of hearing assessments for older adults, especially those diagnosed with dementia, and highlights the significance of objective auditory electrophysiological tests. These tests are presented as vital in assessing the influence of aging and Alzheimer's disease on auditory processing capabilities and to signal cognitive dysfunction. The article underscores the critical role of audiologists in addressing the challenges faced by the aging population. The perspective calls for further research to improve diagnostic and therapeutic strategies in audiology, and emphasizes the need for a multidisciplinary approach in tackling the nexus of hearing loss, auditory processing, and cognitive decline.

Audiovisual perception of interrupted speech by nonnative listeners.

The purpose of the present study was to examine the influence of visual cues in audiovisual perception of interrupted speech by nonnative English listeners and to identify the role of working memory, long-term memory retrieval, and vocabulary knowledge in audiovisual perception by nonnative listeners. The participants included 31 Mandarin-speaking English learners between 19 and 41 years of age. The perceptual stimuli were noise-filled periodically interrupted AzBio and QuickSIN sentences with or without visual cues that showed a male speaker uttering the sentences. In addition to sentence recognition, the listeners completed a semantic fluency task, verbal (operation span) and visuospatial (symmetry span) working memory tasks, and two vocabulary knowledge tests (Vocabulary Level Test and Lexical Test for Advanced Learners of English). The results revealed significantly better speech recognition in the audio-visual condition than the audio-only condition, but the magnitude of visual benefit was substantially attenuated for sentences that had limited semantic context. The listeners' vocabulary size in English played a key role in the restoration of missing speech information and audiovisual integration in the perception of interrupted speech. Meanwhile, the listeners' verbal working memory capacity played an important role in audiovisual integration especially for the difficult stimuli with limited semantic context.

Electrode Impedance Fluctuations and Sudden Decline in Cochlear-Implant Benefit.

OBJECTIVE: The main objective of this clinical capsule was to outline the narrative of three teen cochlear implant (CI) users who experienced a sudden increase in their CI electrode impedance values, which coincided with decreased overall speech perception ability. In addition, the study explored the following questions: Are there any similarities between cases? What recommendations should be made for continuing treatment regarding these cases? PATIENTS: Three teenagers who reported sudden change in CI benefit were included in this study. INTERVENTIONS: Electrode impedance values and speech identification scores were obtained routinely during the CI mapping appointments. Specifically, word and sentence recognition scores were obtained using the Consonant-Nucleus-Consonant word list and the AZBio sentence test, respectively. Both patient 1 and patient 2 underwent CI reimplantation operations as a result of their perceived difficulties and decreased impedances. Patient 3 did not undergo reimplantation surgery. MAIN OUTCOMES: All three patients' CI electrode impedances and speech perception scores eventually stabilized over time. No relationship could be drawn between revision surgery and stabilization of CI electrode impedances and speech perception scores. CONCLUSIONS: Overall, we found no similarities between cases that could potentially explain the sudden electrode impedance value increase or the decrease in speech perception scores. Each case should be evaluated uniquely and carefully for CI revision operations by frequent monitoring, including mapping and speech perception testing. The most common factor contributing to each teen's eventual resolution of electrode impedance values and speech perception scores was time.

Speech Perception in Noise Predicts Oral Narrative Comprehension in Children With Developmental Language Disorder.

We examined the relative contribution of auditory processing abilities (tone perception and speech perception in noise) after controlling for short-term memory capacity and vocabulary, to narrative language comprehension in children with developmental language disorder. Two hundred and sixteen children with developmental language disorder, ages 6 to 9 years (Mean = 7; 6), were administered multiple measures. The dependent variable was children's score on the narrative comprehension scale of the Test of Narrative Language. Predictors were auditory processing abilities, phonological short-term memory capacity, and language (vocabulary) factors, with age, speech perception in quiet, and non-verbal IQ as covariates. Results showed that narrative comprehension was positively correlated with the majority of the predictors. Regression analysis suggested that speech perception in noise contributed uniquely to narrative comprehension in children with developmental language disorder, over and above all other predictors; however, tone perception tasks failed to explain unique variance. The relative importance of speech perception in noise over tone-perception measures for language comprehension reinforces the need for the assessment and management of listening in noise deficits and makes a compelling case for the functional implications of complex listening situations for children with developmental language disorder.

Effect of Auditory Distraction on Working Memory, Attention Switching, and Listening Comprehension.

The effect of non-informational speech spectrum noise as a distractor on cognitive and listening comprehension ability was examined in fifty-three young, normal hearing adults. Time-controlled tasks were used to measure auditory working memory (WM) capacity and attention switching (AS) ability. Listening comprehension was measured using a lecture, interview, and spoken narratives test. Noise level was individually set to achieve at least 90% or higher speech intelligibility. Participants' listening comprehension in the presence of distracting noise was better on inference questions compared to listening in quiet. Their speed of information processing was also significantly faster in WM and AS tasks in noise. These results were consistent with the view that noise may enhance arousal levels leading to faster information processing during cognitive tasks. Whereas the speed of AS was faster in noise, this rapid switching of attention resulted in more errors in updating items. Participants who processed information faster in noise and did so accurately, more effectively switched their attention to refresh/rehearse recall items within WM. More efficient processing deployed in the presence of noise appeared to have led to improvements in WM performance and making inferences in a listening comprehension task. Additional research is required to examine these findings using background noise that can cause informational masking.

Auditory closure with visual cues: Relationship with working memory and semantic memory.

The role of working memory (WM) and long-term lexical-semantic memory (LTM) in the perception of interrupted speech with and without visual cues, was studied in 29 native English speakers. Perceptual stimuli were periodically interrupted sentences filled with speech noise. The memory measures included an LTM semantic fluency task, verbal WM, and visuo-spatial WM tasks. Whereas perceptual performance in the audio-only condition demonstrated a significant positive association with listeners' semantic fluency, perception in audio-video mode did not. These results imply that when listening to distorted speech without visual cues, listeners rely on lexical-semantic retrieval from LTM to restore missing speech information.

Applied tele-audiology research in clinical practice during the past decade: a scoping review.

OBJECTIVE: The purpose of this scoping review was two-fold, (1) to provide information about the characteristics, type of service delivery, participant information and outcomes related to tele-audiology in clinical popluations, and (2) to describe documented facilitators and barriers to tele-audiology delivery from the perspectives of practitioners and service recipients. Knowledge of these findings can assist audiologists in considering remote service delivery options for their practices. DESIGN: A scoping review was conducted in November 2019 to identify English-language peer-reviewed journal articles published from 1 January 2010 to 30 October 2019 related to remote clinical service delivery in audiology. RESULTS: Thirty-six published research articles were included. Research studies were classified into four broad areas with some articles including more than one area within the scope of their article: Screening (n = 5), Diagnostic (n = 5), Intervention (n = 18), and Perspectives (n = 22). CONCLUSION: Hearing healthcare service delivery is expanding with the changing technological landscape, providing greater opportunities and flexibility for audiologists and patients. There are clear opportunities for interdisciplinary collaboration and for collaboration with on-site local facilitators. Local facilitators, with training, can assist in connecting individuals to follow-up care, provide educational support, and needed hands-on assistance for specialised testing.

Auditory processing in children: Role of working memory and lexical ability in auditory closure.

We examined the relationship between cognitive-linguistic mechanisms and auditory closure ability in children. Sixty-seven school-age children recognized isolated words and keywords in sentences that were interrupted at a rate of 2.5 Hz and 5 Hz. In essence, children were given only 50% of speech information and asked to repeat the complete word or sentence. Children's working memory capacity (WMC), attention, lexical knowledge, and retrieval from long-term memory (LTM) abilities were also measured to model their role in auditory closure ability. Overall, recognition of monosyllabic words and lexically easy multisyllabic words was significantly better at 2.5 Hz interruption rate than 5 Hz. Recognition of lexically hard multisyllabic words and keywords in sentences was better at 5 Hz relative to 2.5 Hz. Based on the best fit generalized "logistic" linear mixed effects models, there was a significant interaction between WMC and lexical difficulty of words. WMC was positively related only to recognition of lexically easy words. Lexical knowledge was found to be crucial for recognition of words and sentences, regardless of interruption rate. In addition, LTM retrieval ability was significantly associated with sentence recognition. These results suggest that lexical knowledge and the ability to retrieve information from LTM is crucial for children's speech recognition in adverse listening situations. Study findings make a compelling case for the assessment and intervention of lexical knowledge and retrieval abilities in children with listening difficulties.

Comparison of Auditory, Language, Memory, and Attention Abilities in Children With and Without Listening Difficulties.

Objectives School-age children with and without parent-reported listening difficulties (LiD) were compared on auditory processing, language, memory, and attention abilities. The objective was to extend what is known so far in the literature about children with LiD by using multiple measures and selective novel measures across the above areas. Design Twenty-six children who were reported by their parents as having LiD and 26 age-matched typically developing children completed clinical tests of auditory processing and multiple measures of language, attention, and memory. All children had normal-range pure-tone hearing thresholds bilaterally. Group differences were examined. Results In addition to significantly poorer speech-perception-in-noise scores, children with LiD had reduced speed and accuracy of word retrieval from long-term memory, poorer short-term memory, sentence recall, and inferencing ability. Statistically significant group differences were of moderate effect size; however, standard test scores of children with LiD were not clinically poor. No statistically significant group differences were observed in attention, working memory capacity, vocabulary, and nonverbal IQ. Conclusions Mild signal-to-noise ratio loss, as reflected by the group mean of children with LiD, supported the children's functional listening problems. In addition, children's relative weakness in select areas of language performance, short-term memory, and long-term memory lexical retrieval speed and accuracy added to previous research on evidence-based areas that need to be evaluated in children with LiD who almost always have heterogenous profiles. Importantly, the functional difficulties faced by children with LiD in relation to their test results indicated, to some extent, that commonly used assessments may not be adequately capturing the children's listening challenges. Supplemental Material https://doi.org/10.23641/asha.12808607.

Auditory distraction in school-age children relative to individual differences in working memory capacity.

We examined susceptibility to auditory distraction and its association to working-memory capacity (WMC) in children (N=125) using a dichotic listening task. Performance in a dichotic listening task was measured with and without distracting multi-talker babble (MTB). Intrusion errors from the to-be-ignored ear and the overall errors of any type between the two conditions were modeled to explain the role of WMC and the potential moderating effect of MTB, while controlling for age. Susceptibility to auditory distraction when represented by the absolute difference in errors between MTB and no-MTB conditions was not associated with WMC and age. That is, children with greater WMC were no better at ignoring interference from babble than children with low WMC. This suggests that irrelevant sounds have obligatory access to verbal short-term memory and are not effectively suppressed by the attention-controlled WM system. However, when ratio of errors with and without MTB was analyzed, children with high WMC made more errors compared to children with low WMC. Developmental improvements in children's WMC do not appear to advantage listening in the presence of distracting background noise. Therefore, enhancement of target speech in children's learning environments is crucial.

Working Memory and Auditory Processing in School-Age Children.

Purpose: Our goal is to present the relationships between working memory (WM) and auditory processing abilities in school-age children. Review and Discussion: We begin with an overview of auditory processing, the conceptualization of auditory processing disorder, and the assessment of auditory processing abilities in children. Next, we describe a model of WM and a model of auditory processing followed by their comparison. Evidence for the relationships between WM and auditory processing abilities in school-age children follows. Specifically, we present evidence for the association (or lack thereof) between WM/attention and auditory processing test performance. Clinical Implications: In conclusion, we describe a new framework for understanding auditory processing abilities in children based on integrated evidence from cognitive science, hearing science, and language science. We also discuss clinical implications in children that could inform future research.

Dominance of persistence over adaptation in forward masking.

Persistence of excitation and neural adaptation are competing theories proposed to explain the mechanisms underlying psychophysical forward masking. Previous research has been directed towards finding models that accurately describe the phenomenon but cannot account for the underlying explanation. The current study was designed to determine which theory best accounts for results obtained from behavioral gap duration adjustment tasks. Thirteen adults adjusted the gap within asymmetrical noise markers to be subjectively equal to the gap within equal-intensity-noise markers. The duration of the perceived gap between the asymmetrical markers is expected to vary depending on which theory dominates perception. The persistence of excitation mechanism would lead to longer duration gaps when the second noise marker is lower in intensity than the preceding. Neural adaptation would result in matched gaps that are shorter in duration when the second noise marker was lower in level. The outcome of our data analysis is consistent with the persistence of excitation as a dominant mechanism in forward masking.

Children's Speech Perception in Noise: Evidence for Dissociation From Language and Working Memory.

Purpose: We examined the association between speech perception in noise (SPIN), language abilities, and working memory (WM) capacity in school-age children. Existing studies supporting the Ease of Language Understanding (ELU) model suggest that WM capacity plays a significant role in adverse listening situations. Method: Eighty-three children between the ages of 7 to 11 years participated. The sample represented a continuum of individual differences in attention, memory, and language abilities. All children had normal-range hearing and normal-range nonverbal IQ. Children completed the Bamford-Kowal-Bench Speech-in-Noise Test (BKB-SIN; Etymotic Research, 2005), a selective auditory attention task, and multiple measures of language and WM. Results: Partial correlations (controlling for age) showed significant positive associations among attention, memory, and language measures. However, BKB-SIN did not correlate significantly with any of the other measures. Principal component analysis revealed a distinct WM factor and a distinct language factor. BKB-SIN loaded robustly as a distinct 3rd factor with minimal secondary loading from sentence recall and short-term memory. Nonverbal IQ loaded as a 4th factor. Conclusions: Results did not support an association between SPIN and WM capacity in children. However, in this study, a single SPIN measure was used. Future studies using multiple SPIN measures are warranted. Evidence from the current study supports the use of BKB-SIN as clinical measure of speech perception ability because it was not influenced by variation in children's language and memory abilities. More large-scale studies in school-age children are needed to replicate the proposed role played by WM in adverse listening situations.

Working Memory and Speech Comprehension in Older Adults With Hearing Impairment.

Purpose: This study examined the relationship between working memory (WM) and speech comprehension in older adults with hearing impairment (HI). It was hypothesized that WM would explain significant variance in speech comprehension measured in multitalker babble (MTB). Method: Twenty-four older (59-73 years) adults with sensorineural HI participated. WM capacity (WMC) was measured using 3 complex span tasks. Speech comprehension was assessed using multiple passages, and speech identification ability was measured using recall of sentence final-word and key words. Speech measures were performed in quiet and in the presence of MTB at + 5 dB signal-to-noise ratio. Results: Results suggested that participants' speech identification was poorer in MTB, but their ability to comprehend discourse in MTB was at least as good as in quiet. WMC did not explain significant variance in speech comprehension before and after controlling for age and audibility. However, WMC explained significant variance in low-context sentence key words identification in MTB. Conclusions: These results suggest that WMC plays an important role in identifying low-context sentences in MTB, but not when comprehending semantically rich discourse passages. In general, data did not support individual variability in WMC as a factor that predicts speech comprehension ability in older adults with HI.

Role of working memory and lexical knowledge in perceptual restoration of interrupted speech.

The role of working memory (WM) capacity and lexical knowledge in perceptual restoration (PR) of missing speech was investigated using the interrupted speech perception paradigm. Speech identification ability, which indexed PR, was measured using low-context sentences periodically interrupted at 1.5 Hz. PR was measured for silent gated, low-frequency speech noise filled, and low-frequency fine-structure and envelope filled interrupted conditions. WM capacity was measured using verbal and visuospatial span tasks. Lexical knowledge was assessed using both receptive vocabulary and meaning from context tests. Results showed that PR was better for speech noise filled condition than other conditions tested. Both receptive vocabulary and verbal WM capacity explained unique variance in PR for the speech noise filled condition, but were unrelated to performance in the silent gated condition. It was only receptive vocabulary that uniquely predicted PR for fine-structure and envelope filled conditions. These findings suggest that the contribution of lexical knowledge and verbal WM during PR depends crucially on the information content that replaced the silent intervals. When perceptual continuity was partially restored by filler speech noise, both lexical knowledge and verbal WM capacity facilitated PR. Importantly, for fine-structure and envelope filled interrupted conditions, lexical knowledge was crucial for PR.

Amplitude modulation detection with concurrent frequency modulation.

Human speech consists of concomitant temporal modulations in amplitude and frequency that are crucial for speech perception. In this study, amplitude modulation (AM) detection thresholds were measured for 550 and 5000 Hz carriers with and without concurrent frequency modulation (FM), at AM rates crucial for speech perception. Results indicate that adding 40 Hz FM interferes with AM detection, more so for 5000 Hz carrier and for frequency deviations exceeding the critical bandwidth of the carrier frequency. These findings suggest that future cochlear implant processors, encoding speech fine-structures may consider limiting the FM to narrow bandwidth and to low frequencies.

No evidence of relation between working memory and perception of interrupted speech in young adults.

Understanding interrupted speech requires top-down linguistic and cognitive restoration mechanisms. To investigate the relation between working memory (WM) and perception of interrupted speech, 20 young adults were asked to recognize sentences interrupted at 2 Hz, 8 Hz, and a combination of 2 and 8 Hz. WM was measured using automated reading and operation span tasks. Interestingly, the results presented here revealed no statistical relation between any of the interrupted speech recognition scores and WM scores. This finding is in agreement with previous findings that suggest greater reliance on linguistic factors relative to cognitive factors during perception of interrupted speech.

High- and Low-Frequency Decrement Contribution to Spectral Enhancement.

PURPOSE: The relative benefit of a single, flanking, high- or low-frequency decrement was assessed to better understand properties of spectral enhancement that may aid in algorithm design. METHOD: Detection thresholds were measured for intensity increments applied to a narrow target band of frequencies embedded in a broadband signal while 400-Hz-wide, 9- or 12-dB-deep intensity decrements were placed above, below, or on both sides of the target band. A mono condition with no decrements was used as a control. Eight participants with normal hearing and 8 participants with hearing impairment took part in this experiment. RESULTS: Performance improved in the presence of decrements for both groups and was equivalent for both high- or low-frequency decrements. Comparison with individually measured auditory filters revealed that participants with normal hearing made use of energy cues available within these filters, whereas some participants with hearing impairment, despite improved increment detection, underutilized this information. CONCLUSION: Inclusion of a single, adjacent, high- or low-frequency decrement improved increment detection but not to the same extent as when decrements flanked both sides.

Overview of Central Auditory Processing Deficits in Older Adults.

Although there are many reported age-related declines in the human body, the notion that a central auditory processing deficit exists in older adults has not always been clear. Hearing loss and both structural and functional central nervous system changes with advancing age are contributors to how we listen, hear, and process auditory information. Even older adults with normal or near normal hearing sensitivity may exhibit age-related central auditory processing deficits as measured behaviorally and/or electrophysiologically. The purpose of this article is to provide an overview of assessment and rehabilitative approaches for central auditory processing deficits in older adults. It is hoped that the outcome of the information presented here will help clinicians with older adult patients who do not exhibit the typical auditory processing behaviors exhibited by others at the same age and with comparable hearing sensitivity all in the absence of other health-related conditions.

Effects of transient noise reduction algorithms on speech intelligibility and ratings of hearing aid users.

PURPOSE: The goal of this study was to assess the functional utility of transient noise reduction (TNR) algorithms available in hearing aids via speech intelligibility and user preferences. METHOD: Two pairs of hearing aids, 1 pair each from Siemens and Unitron, were programmed for 17 hearing impaired individuals after a hearing evaluation. Intelligibility was measured for each participant for sentences presented in quiet, with 2 types of transient noise, multitalker babble, and in a combination of each type of transient noise and multitalker babble. Each condition was tested with TNR activated and TNR deactivated in a counterbalanced, single-blinded format. Subjective ratings of overall speech understanding, comfort, and sound quality were obtained for each condition. RESULTS: A significant improvement in speech intelligibility was measured with the TNR activated when speech was presented in multitalker babble, in the presence of chair clang transient noises, and when combining these noises. Activation of the TNR algorithm did not result in significant improvements for any of the subjective ratings. CONCLUSIONS: While improvements were limited to certain conditions, specifically those with the chair clang transient and/or multitalker babble, TNR appears to offer an incremental step in improving the listening experience for hearing aid users.