Elucidating the effects of ageing on remembering perceptually distorted word pairs

Relationships between behavioural and self-report measures in speech recognition in noise

OBJECTIVE

Using data from the n200-study, we aimed to investigate the relationship between behavioural (the Swedish HINT and Hagerman speech-in-noise tests) and self-report (Speech, Spatial and Qualities of Hearing Questionnaire (SSQ)) measures of listening under adverse conditions.

DESIGN

The Swedish HINT was masked with a speech-shaped noise (SSN), the Hagerman was masked with a SSN and a four-talker babble, and the subscales from the SSQ were used as a self-report measure. The HINT and Hagerman were administered through an experimental hearing aid.

STUDY SAMPLE

This study included 191 hearing aid users with hearing loss (mean PTA4 = 37.6, SD = 10.8) and 195 normally hearing adults (mean PTA4 = 10.0, SD = 6.0).

RESULTS

The present study found correlations between behavioural measures of speech-in-noise and self-report scores of the SSQ in normally hearing individuals, but not in hearing aid users.

CONCLUSION

The present study may help identify relationships between clinically used behavioural measures, and a self-report measure of speech recognition. The results from the present study suggest that use of a self-report measure as a complement to behavioural speech in noise tests might help to further our understanding of how self-report, and behavioural results can be generalised to everyday functioning.

Intelligibility as a measure of speech perception: Current approaches, challenges, and recommendations

Intelligibility measures, which assess the number of words or phonemes a listener correctly transcribes or repeats, are commonly used metrics for speech perception research. While these measures have many benefits for researchers, they also come with a number of limitations. By pointing out the strengths and limitations of this approach, including how it fails to capture aspects of perception such as listening effort, this article argues that the role of intelligibility measures must be reconsidered in fields such as linguistics, communication disorders, and psychology. Recommendations for future work in this area are presented.

Perception of Physical Demand, Mental Demand, and Performance: A Comparison of Two Voice Interventions for Parkinson's Disease

PURPOSE

The purpose of the study was to examine the effect of two voice intervention approaches for hypophonia secondary to Parkinson's disease (PD) on self-reported measures of physical demand, mental demand, and vocal performance.

METHOD

Thirty-four persons with hypophonia secondary to PD were assigned to one of three groups: Lee Silverman Voice Treatment (LSVT) LOUD (n = 12), SpeechVive (n = 12), and nontreatment clinical control (n = 10). The LSVT LOUD and the SpeechVive participants received 8 weeks of voice intervention following the standardized protocol previously described for each approach. To confirm the effectiveness of each voice intervention, sound pressure level (dB SPL) data were analyzed for the experimental and control participants for a monologue sample obtained pretreatment, midtreatment, and posttreatment. During the voice intervention period, the LSVT LOUD and the SpeechVive participants were instructed to complete a modified version of the National Aeronautics and Space Administration Task Load Index rating scale to indicate the mental and physical demand required to complete the intervention activities, and to indicate how well they performed in completing the assigned vocal tasks.

RESULTS

The LSVT LOUD and the SpeechVive participants demonstrated a significant posttreatment increase in SPL (dB), in comparison to the clinical controls, thus confirming a positive intervention effect. The LSVT LOUD participants reported significantly higher ratings of physical and mental demand over the course of treatment, in comparison to the SpeechVive participants.

CONCLUSION

Consideration of the mental and physical demand associated with two voice intervention approaches, commonly used for PD, may help to foster improved therapeutic compliance and treatment outcomes.

The cognitive hearing science perspective on perceiving, understanding, and remembering language: The ELU model

The review gives an introductory description of the successive development of data patterns based on comparisons between hearing-impaired and normal hearing participants’ speech understanding skills, later prompting the formulation of the Ease of Language Understanding (ELU) model. The model builds on the interaction between an input buffer (RAMBPHO, Rapid Automatic Multimodal Binding of PHOnology) and three memory systems: working memory (WM), semantic long-term memory (SLTM), and episodic long-term memory (ELTM). RAMBPHO input may either match or mismatch multimodal SLTM representations. Given a match, lexical access is accomplished rapidly and implicitly within approximately 100–400 ms. Given a mismatch, the prediction is that WM is engaged explicitly to repair the meaning of the input – in interaction with SLTM and ELTM – taking seconds rather than milliseconds. The multimodal and multilevel nature of representations held in WM and LTM are at the center of the review, being integral parts of the prediction and postdiction components of language understanding. Finally, some hypotheses based on a selective use-disuse of memory systems mechanism are described in relation to mild cognitive impairment and dementia. Alternative speech perception and WM models are evaluated, and recent developments and generalisations, ELU model tests, and boundaries are discussed.

Listening Effort Informed Quality of Experience Evaluation

Perceived quality of experience for speech listening is influenced by cognitive processing and can affect a listener's comprehension, engagement and responsiveness. Quality of Experience (QoE) is a paradigm used within the media technology community to assess media quality by linking quantifiable media parameters to perceived quality. The established QoE framework provides a general definition of QoE, categories of possible quality influencing factors, and an identified QoE formation pathway. These assist researchers to implement experiments and to evaluate perceived quality for any applications. The QoE formation pathways in the current framework do not attempt to capture cognitive effort effects and the standard experimental assessments of QoE minimize the influence from cognitive processes. The impact of cognitive processes and how they can be captured within the QoE framework have not been systematically studied by the QoE research community. This article reviews research from the fields of audiology and cognitive science regarding how cognitive processes influence the quality of listening experience. The cognitive listening mechanism theories are compared with the QoE formation mechanism in terms of the quality contributing factors, experience formation pathways, and measures for experience. The review prompts a proposal to integrate mechanisms from audiology and cognitive science into the existing QoE framework in order to properly account for cognitive load in speech listening. The article concludes with a discussion regarding how an extended framework could facilitate measurement of QoE in broader and more realistic application scenarios where cognitive effort is a material consideration.

Reproducibility in Cognitive Hearing Research: Theoretical Considerations and Their Practical Application in Multi-Lab Studies

In this article, we consider the issue of reproducibility within the field of cognitive hearing science. First, we examine how retest reliability can provide useful information for the generality of results and intervention effectiveness. Second, we provide an overview of retest reliability coefficients within three areas of cognitive hearing science (cognition, speech perception, and self-reported measures of communication) and show how the reporting of these coefficients differs between fields. We argue that practices surrounding the provision of retest coefficients are currently most rigorous in clinical assessment and that basic science research would benefit from adopting similar standards. Finally, based on a distinction between direct replications (which aim to keep materials as close to the original study as possible) and conceptual replications (which test the same purported mechanism using different materials), we discuss new initiatives which address the need for both. Using the example of the auditory Stroop task, we provide practical illustrations of how these theoretical issues can be addressed within the context of a multi-lab replication study. By illustrating how theoretical concepts can be put into practice in empirical research, we hope to encourage others to set up and participate in a wide variety of reproducibility-related studies.

On the Possible Overestimation of Cognitive Decline: The Impact of Age-Related Hearing Loss on Cognitive-Test Performance

Individual differences and age-related normal and pathological changes in mental abilities require the use of cognitive screening and assessment tools. However, simultaneously occurring deficits in sensory processing, whose prevalence increases especially in old age, may negatively impact cognitive-test performance and thus result in an overestimation of cognitive decline. This hypothesis was tested using an impairment-simulation approach. Young normal-hearing university students performed three memory tasks, using auditorily presented speech stimuli that were either unprocessed or processed to mimic some of the perceptual consequences of age-related hearing loss (ARHL). Both short-term-memory and working-memory capacities were significantly lower in the simulated-hearing-loss condition, despite good intelligibility of the test stimuli. The findings are consistent with the notion that, in case of ARHL, the perceptual processing of auditory stimuli used in cognitive assessments requires additional (cognitive) resources that cannot be used toward the execution of the cognitive task itself. Researchers and clinicians would be well advised to consider sensory impairments as a confounding variable when administering cognitive tasks and interpreting their results.

Card playing enhances speech perception among aging adults: comparison with aging musicians

Speech perception and auditory processing have been shown to be enhanced among aging musicians as compared to non-musicians. In the present study, the aim was to test whether these functions are also enhanced among those who are engaged in a non-musical mentally challenging leisure activity (card playing). Three groups of 23 aging adults, aged 60-80 years, were recruited for the study: Musicians, Card players, and Controls. Participants were matched for age, gender, Wechsler Adult Intelligence Scale-III Matrix Reasoning, and Digit Span scores. Their performance was measured using auditory spectral and spatial temporal order judgment tests, and four tasks of speech perception in conditions of: no background noise, background noise of speech frequencies, background noise of white noise, and 60% compressed speech. Musicians were better in auditory and speech perception than the other two groups. Card players were similar to Controls in auditory perception tasks, but were better in the speech perception tasks. Non-musician aging adults may be able to improve their speech perception ability by engaging in leisure activity requiring cognitive effort.

Listening Effort: How the Cognitive Consequences of Acoustic Challenge Are Reflected in Brain and Behavior

Everyday conversation frequently includes challenges to the clarity of the acoustic speech signal, including hearing impairment, background noise, and foreign accents. Although an obvious problem is the increased risk of making word identification errors, extracting meaning from a degraded acoustic signal is also cognitively demanding, which contributes to increased listening effort. The concepts of cognitive demand and listening effort are critical in understanding the challenges listeners face in comprehension, which are not fully predicted by audiometric measures. In this article, the authors review converging behavioral, pupillometric, and neuroimaging evidence that understanding acoustically degraded speech requires additional cognitive support and that this cognitive load can interfere with other operations such as language processing and memory for what has been heard. Behaviorally, acoustic challenge is associated with increased errors in speech understanding, poorer performance on concurrent secondary tasks, more difficulty processing linguistically complex sentences, and reduced memory for verbal material. Measures of pupil dilation support the challenge associated with processing a degraded acoustic signal, indirectly reflecting an increase in neural activity. Finally, functional brain imaging reveals that the neural resources required to understand degraded speech extend beyond traditional perisylvian language networks, most commonly including regions of prefrontal cortex, premotor cortex, and the cingulo-opercular network. Far from being exclusively an auditory problem, acoustic degradation presents listeners with a systems-level challenge that requires the allocation of executive cognitive resources. An important point is that a number of dissociable processes can be engaged to understand degraded speech, including verbal working memory and attention-based performance monitoring. The specific resources required likely differ as a function of the acoustic, linguistic, and cognitive demands of the task, as well as individual differences in listeners' abilities. A greater appreciation of cognitive contributions to processing degraded speech is critical in understanding individual differences in comprehension ability, variability in the efficacy of assistive devices, and guiding rehabilitation approaches to reducing listening effort and facilitating communication.

Mensuração do esforço auditivo com o uso de um paradigma de tarefa dupla do Português Brasileiro: estudo-piloto

RESUMO Objetivo Mensurar o esforço auditivo com o uso de um paradigma de tarefa dupla de memória operacional e analisar a significância clínica do desempenho de indivíduos normo-ouvintes. Método Participaram 10 adultos jovens, entre 18 e 30 anos, de ambos os gêneros, normo-ouvintes classificados segundo a média quadritonal (500, 1000, 2000 e 4000Hz) e com nível sociocultural similar. Os participantes foram submetidos à anamnese audiológica, meatoscopia e audiometria tonal limiar. Para a mensuração do esforço auditivo, utilizou-se um paradigma de tarefa dupla, composto por tarefas de percepção de fala e memória operacional de logatomas, palavras reais e sentenças sem sentido. Anteriormente à mensuração, o paradigma de tarefa dupla foi realizado no silêncio com o intuito de treinar os participantes a desempenharem as tarefas adequadamente. Após a fase de treinamento, este paradigma foi realizado em duas situações de escuta distintas, nas relações sinal/ruído de +5 e -5dB, com o ruído do tipo White Noise. Resultados A comparação do desempenho por orelha, direita ou esquerda, nas duas relações sinal-ruído demonstrou efeito significante para as tarefas de percepção de fala de logatomas e sentenças sem sentido em ambas as orelhas, porém para a tarefa de esforço auditivo e memória operacional houve diferença significante apenas para a orelha direita. Conclusão Foi possível mensurar o esforço auditivo com o uso do paradigma proposto e este instrumento demonstrou ser sensível para a quantificação deste parâmetro auditivo.

Eyes and ears: Using eye tracking and pupillometry to understand challenges to speech recognition

Although human speech recognition is often experienced as relatively effortless, a number of common challenges can render the task more difficult. Such challenges may originate in talkers (e.g., unfamiliar accents, varying speech styles), the environment (e.g. noise), or in listeners themselves (e.g., hearing loss, aging, different native language backgrounds). Each of these challenges can reduce the intelligibility of spoken language, but even when intelligibility remains high, they can place greater processing demands on listeners. Noisy conditions, for example, can lead to poorer recall for speech, even when it has been correctly understood. Speech intelligibility measures, memory tasks, and subjective reports of listener difficulty all provide critical information about the effects of such challenges on speech recognition. Eye tracking and pupillometry complement these methods by providing objective physiological measures of online cognitive processing during listening. Eye tracking records the moment-to-moment direction of listeners' visual attention, which is closely time-locked to unfolding speech signals, and pupillometry measures the moment-to-moment size of listeners' pupils, which dilate in response to increased cognitive load. In this paper, we review the uses of these two methods for studying challenges to speech recognition.

Disregarding hearing loss leads to overestimation of age-related cognitive decline

Aging is associated with cognitive and sensory decline. While several studies have indicated greater cognitive decline among older adults with hearing loss, the extent to which age-related differences in cognitive processing may have been overestimated due to group differences in sensory processing has remained unclear. We addressed this question by comparing younger adults, older adults with good hearing, and older adults with poor hearing in several cognitive domains: working memory, selective attention, processing speed, inhibitory control, and abstract reasoning. Furthermore, we examined whether sensory-related cognitive decline depends on cognitive demands and on the sensory modality used for assessment. Our results revealed that age-related cognitive deficits in most cognitive domains varied as a function of hearing loss, being more pronounced in older adults with poor hearing. Furthermore, sensory-related cognitive decline was observed across different levels of cognitive demands and independent of the sensory modality used for cognitive assessment, suggesting a generalized effect of age-related hearing loss on cognitive functioning. As most cognitive aging studies have not taken sensory acuity into account, age-related cognitive decline may have been overestimated.

Age equivalence in the benefit of repetition for speech understanding

Although repetition is the most commonly used conversational repair strategy, little is known about its relative effectiveness among listeners spanning the adult age range. The purpose of this study was to identify differences in how younger, middle-aged, and older adults were able to use immediate repetition to improve speech recognition in the presence of different kinds of maskers. Results suggest that all groups received approximately the same amount of benefit from repetition. Repetition benefit was largest when the masker was fluctuating noise and smallest when it was competing speech.

Aging and Spectro-Temporal Integration of Speech

The purpose of this study was to determine the effects of age on the spectro-temporal integration of speech. The hypothesis was that the integration of speech fragments distributed over frequency, time, and ear of presentation is reduced in older listeners-even for those with good audiometric hearing. Younger, middle-aged, and older listeners (10 per group) with good audiometric hearing participated. They were each tested under seven conditions that encompassed combinations of spectral, temporal, and binaural integration. Sentences were filtered into two bands centered at 500 Hz and 2500 Hz, with criterion bandwidth tailored for each participant. In some conditions, the speech bands were individually square wave interrupted at a rate of 10 Hz. Configurations of uninterrupted, synchronously interrupted, and asynchronously interrupted frequency bands were constructed that constituted speech fragments distributed across frequency, time, and ear of presentation. The over-arching finding was that, for most configurations, performance was not differentially affected by listener age. Although speech intelligibility varied across condition, there was no evidence of performance deficits in older listeners in any condition. This study indicates that age, per se, does not necessarily undermine the ability to integrate fragments of speech dispersed across frequency and time.

Effects of Age on Long Term Memory for Degraded Speech

Prior research suggests that acoustical degradation impacts encoding of items into memory, especially in elderly subjects. We here aimed to investigate whether acoustically degraded items that are initially encoded into memory are more prone to forgetting as a function of age. Young and old participants were tested with a vocoded and unvocoded serial list learning task involving immediate and delayed free recall. We found that degraded auditory input increased forgetting of previously encoded items, especially in older participants. We further found that working memory capacity predicted forgetting of degraded information in young participants. In old participants, verbal IQ was the most important predictor for forgetting acoustically degraded information. Our data provide evidence that acoustically degraded information, even if encoded, is especially vulnerable to forgetting in old age.

The Neural Consequences of Age-Related Hearing Loss

During hearing, acoustic signals travel up the ascending auditory pathway from the cochlea to auditory cortex; efferent connections provide descending feedback. In human listeners, although auditory and cognitive processing have sometimes been viewed as separate domains, a growing body of work suggests they are intimately coupled. Here, we review the effects of hearing loss on neural systems supporting spoken language comprehension, beginning with age-related physiological decline. We suggest that listeners recruit domain general executive systems to maintain successful communication when the auditory signal is degraded, but that this compensatory processing has behavioral consequences: even relatively mild levels of hearing loss can lead to cascading cognitive effects that impact perception, comprehension, and memory, leading to increased listening effort during speech comprehension.

Effects of Aging and Adult-Onset Hearing Loss on Cortical Auditory Regions

Hearing loss is a common feature in human aging. It has been argued that dysfunctions in central processing are important contributing factors to hearing loss during older age. Aging also has well documented consequences for neural structure and function, but it is not clear how these effects interact with those that arise as a consequence of hearing loss. This paper reviews the effects of aging and adult-onset hearing loss in the structure and function of cortical auditory regions. The evidence reviewed suggests that aging and hearing loss result in atrophy of cortical auditory regions and stronger engagement of networks involved in the detection of salient events, adaptive control and re-allocation of attention. These cortical mechanisms are engaged during listening in effortful conditions in normal hearing individuals. Therefore, as a consequence of aging and hearing loss, all listening becomes effortful and cognitive load is constantly high, reducing the amount of available cognitive resources. This constant effortful listening and reduced cognitive spare capacity could be what accelerates cognitive decline in older adults with hearing loss.

How Age and Linguistic Competence Affect Memory for Heard Information

The short-term memory performance of a group of younger adults, for whom English was a second language (young EL2 listeners), was compared to that of younger and older adults for whom English was their first language (EL1 listeners). To-be-remembered words were presented in noise and in quiet. When presented in noise, the listening situation was adjusted to ensure that the likelihood of recognizing the individual words was comparable for all groups. Previous studies which used the same paradigm found memory performance of older EL1 adults on this paired-associate task to be poorer than that of their younger EL1 counterparts both in quiet and in a background of babble. The purpose of the present study was to investigate whether the less well-established semantic and linguistic skills of EL2 listeners would also lead to memory deficits even after equating for word recognition as was done for the younger and older EL1 listeners. No significant differences in memory performance were found between young EL1 and EL2 listeners after equating for word recognition, indicating that the EL2 listeners' poorer semantic and linguistic skills had little effect on their ability to memorize and recall paired associates. This result is consistent with the hypothesis that age-related declines in memory are primarily due to age-related declines in higher-order processes supporting stream segregation and episodic memory. Such declines are likely to increase the load on higher-order (possibly limited) cognitive processes supporting memory. The problems that these results pose for the comprehension of spoken language in these three groups are discussed.

The effect of functional hearing loss and age on long- and short-term visuospatial memory: evidence from the UK biobank resource

The UK Biobank offers cross-sectional epidemiological data collected on >500,000 individuals in the UK between 40 and 70 years of age. Using the UK Biobank data, the aim of this study was to investigate the effects of functional hearing loss and hearing aid usage on visuospatial memory function. This selection of variables resulted in a sub-sample of 138,098 participants after discarding extreme values. A digit triplets functional hearing test was used to divide the participants into three groups: poor, insufficient and normal hearers. We found negative relationships between functional hearing loss and both visuospatial working memory (i.e., a card pair matching task) and visuospatial, episodic long-term memory (i.e., a prospective memory task), with the strongest association for episodic long-term memory. The use of hearing aids showed a small positive effect for working memory performance for the poor hearers, but did not have any influence on episodic long-term memory. Age also showed strong main effects for both memory tasks and interacted with gender and education for the long-term memory task. Broader theoretical implications based on a memory systems approach will be discussed and compared to theoretical alternatives.

Methodological challenges and solutions in auditory functional magnetic resonance imaging

Functional magnetic resonance imaging (fMRI) studies involve substantial acoustic noise. This review covers the difficulties posed by such noise for auditory neuroscience, as well as a number of possible solutions that have emerged. Acoustic noise can affect the processing of auditory stimuli by making them inaudible or unintelligible, and can result in reduced sensitivity to auditory activation in auditory cortex. Equally importantly, acoustic noise may also lead to increased listening effort, meaning that even when auditory stimuli are perceived, neural processing may differ from when the same stimuli are presented in quiet. These and other challenges have motivated a number of approaches for collecting auditory fMRI data. Although using a continuous echoplanar imaging (EPI) sequence provides high quality imaging data, these data may also be contaminated by background acoustic noise. Traditional sparse imaging has the advantage of avoiding acoustic noise during stimulus presentation, but at a cost of reduced temporal resolution. Recently, three classes of techniques have been developed to circumvent these limitations. The first is Interleaved Silent Steady State (ISSS) imaging, a variation of sparse imaging that involves collecting multiple volumes following a silent period while maintaining steady-state longitudinal magnetization. The second involves active noise control to limit the impact of acoustic scanner noise. Finally, novel MRI sequences that reduce the amount of acoustic noise produced during fMRI make the use of continuous scanning a more practical option. Together these advances provide unprecedented opportunities for researchers to collect high-quality data of hemodynamic responses to auditory stimuli using fMRI.

Effects of noise and working memory capacity on memory processing of speech for hearing-aid users

OBJECTIVES

It has been shown that noise reduction algorithms can reduce the negative effects of noise on memory processing in persons with normal hearing. The objective of the present study was to investigate whether a similar effect can be obtained for persons with hearing impairment and whether such an effect is dependent on individual differences in working memory capacity.

DESIGN

A sentence-final word identification and recall (SWIR) test was conducted in two noise backgrounds with and without noise reduction as well as in quiet. Working memory capacity was measured using a reading span (RS) test.

STUDY SAMPLE

Twenty-six experienced hearing-aid users with moderate to moderately severe sensorineural hearing loss.

RESULTS

Noise impaired recall performance. Competing speech disrupted memory performance more than speech-shaped noise. For late list items the disruptive effect of the competing speech background was virtually cancelled out by noise reduction for persons with high working memory capacity.

CONCLUSIONS

Noise reduction can reduce the adverse effect of noise on memory for speech for persons with good working memory capacity. We argue that the mechanism behind this is faster word identification that enhances encoding into working memory.

Adverse listening conditions and memory load drive a common α oscillatory network

How does acoustic degradation affect the neural mechanisms of working memory? Enhanced alpha oscillations (8-13 Hz) during retention of items in working memory are often interpreted to reflect increased demands on storage and inhibition. We hypothesized that auditory signal degradation poses an additional challenge to human listeners partly because it draws on the same neural mechanisms. In an adapted Sternberg paradigm, auditory memory load and acoustic degradation were parametrically varied and the magnetoencephalographic response was analyzed in the time-frequency domain. Notably, during the stimulus-free delay interval, alpha power monotonically increased at central-parietal sensors as functions of memory load (higher alpha power with more memory load) and of acoustic degradation (also higher alpha power with more severe acoustic degradation). This alpha effect was superadditive when highest load was combined with most severe degradation. Moreover, alpha oscillatory dynamics during stimulus-free delay were predictive of response times to the probe item. Source localization of alpha power during stimulus-free delay indicated that alpha generators in right parietal, cingulate, supramarginal, and superior temporal cortex were sensitive to combined memory load and acoustic degradation. In summary, both challenges of memory load and acoustic degradation increase activity in a common alpha-frequency network. The results set the stage for future studies on how chronic or acute degradations of sensory input affect mechanisms of executive control.

Hearing loss in older adults affects neural systems supporting speech comprehension

Hearing loss is one of the most common complaints in adults over the age of 60 and a major contributor to difficulties in speech comprehension. To examine the effects of hearing ability on the neural processes supporting spoken language processing in humans, we used functional magnetic resonance imaging to monitor brain activity while older adults with age-normal hearing listened to sentences that varied in their linguistic demands. Individual differences in hearing ability predicted the degree of language-driven neural recruitment during auditory sentence comprehension in bilateral superior temporal gyri (including primary auditory cortex), thalamus, and brainstem. In a second experiment, we examined the relationship of hearing ability to cortical structural integrity using voxel-based morphometry, demonstrating a significant linear relationship between hearing ability and gray matter volume in primary auditory cortex. Together, these results suggest that even moderate declines in peripheral auditory acuity lead to a systematic downregulation of neural activity during the processing of higher-level aspects of speech, and may also contribute to loss of gray matter volume in primary auditory cortex. More generally, these findings support a resource-allocation framework in which individual differences in sensory ability help define the degree to which brain regions are recruited in service of a particular task.

Cognitive hearing science: the legacy of Stuart Gatehouse

Stuart Gatehouse was one of the pioneers of cognitive hearing science. The ease of language understanding (ELU) model (Rönnberg) is one example of a cognitive hearing science model where the interplay between memory systems and signal processing is emphasized. The mismatch notion is central to ELU and concerns how phonological information derived from the signal, matches/mismatches phonological representations in lexical and semantic long-term memory (LTM). When signals match, processing is rapid, automatic and implicit, and lexical activation proceeds smoothly. Given a mismatch, lexical activation fails, and working or short-term memory (WM/STM) is assumed to be invoked to engage in explicit repair strategies to disambiguate what was said in the conversation. In a recent study, negative long-term consequences of mismatch were found by means of relating hearing loss to episodic LTM in a sample of old hearing-aid wearers. STM was intact (Rönnberg et al.). Beneficial short-term consequences of a binary masking noise reduction scheme on STM was obtained in 4-talker babble for individuals with high WM capacity, but not in stationary noise backgrounds (Ng et al.). This suggests that individuals high on WM capacity inhibit semantic auditory distraction in 4-talker babble while exploiting the phonological benefits in terms of speech quality provided by binary masking (Wang). Both long-term and short-term mismatch effects, apparent in data sets including behavioral as well as subjective (Rudner et al.) data, need to be taken into account in the design of future hearing instruments.

Hearing loss is negatively related to episodic and semantic long-term memory but not to short-term memory

PURPOSE

To test the relationship between degree of hearing loss and different memory systems in hearing aid users.

METHOD

Structural equation modeling (SEM) was used to study the relationship between auditory and visual acuity and different cognitive and memory functions in an age-hetereogenous subsample of 160 hearing aid users without dementia, drawn from the Swedish prospective cohort aging study known as Betula (L.-G. Nilsson et al., 1997).

RESULTS

Hearing loss was selectively and negatively related to episodic and semantic long-term memory (LTM) but not short-term memory (STM) performance. This held true for both ears, even when age was accounted for. Visual acuity alone, or in combination with auditory acuity, did not contribute to any acceptable SEM solution.

CONCLUSIONS

The overall relationships between hearing loss and memory systems were predicted by the ease of language understanding model (J. Rönnberg, 2003), but the exact mechanisms of episodic memory decline in hearing aid users (i.e., mismatch/disuse, attentional resources, or information degradation) remain open for further experiments. The hearing aid industry should strive to design signal processing algorithms that are cognition friendly.

How Age Affects Auditory-Cognitive Interactions in Speech Comprehension

To participate effectively in multi-talker conversations, listeners need to do more than simply recognize and repeat speech. They have to keep track of who said what, extract the meaning of each utterance, store it in memory for future use, integrate the incoming information with what each conversational participant has said in the past, and draw on the listener’s own knowledge of the topic under consideration to extract general themes and formulate responses. In other words, to acquire and use the information contained in spoken language requires the smooth and rapid functioning of an integrated system of perceptual and cognitive processes. Here we review evidence indicating that the operation of this integrated system of perceptual and cognitive processes is more easily disrupted in older than in younger adults, especially when there are competing sounds in the auditory scene.