M. Kathleen Pichora-Fuller

The Ease of Language Understanding (ELU) model: theoretical, empirical, and clinical advances

Working memory is important for online language processing during conversation. We use it to maintain relevant information, to inhibit or ignore irrelevant information, and to attend to conversation selectively. Working memory helps us to keep track of and actively participate in conversation, including taking turns and following the gist. This paper examines the Ease of Language Understanding model (i.e., the ELU model, Rönnberg, 2003; Rönnberg et al., 2008) in light of new behavioral and neural findings concerning the role of working memory capacity (WMC) in uni-modal and bimodal language processing. The new ELU model is a meaning prediction system that depends on phonological and semantic interactions in rapid implicit and slower explicit processing mechanisms that both depend on WMC albeit in different ways. It is based on findings that address the relationship between WMC and (a) early attention processes in listening to speech, (b) signal processing in hearing aids and its effects on short-term memory, (c) inhibition of speech maskers and its effect on episodic long-term memory, (d) the effects of hearing impairment on episodic and semantic long-term memory, and finally, (e) listening effort. New predictions and clinical implications are outlined. Comparisons with other WMC and speech perception models are made.

Effects of age on auditory and cognitive processing: implications for hearing aid fitting and audiologic rehabilitation.

Recent advances in research and clinical practice concerning aging and auditory communication have been driven by questions about age-related differences in peripheral hearing, central auditory processing, and cognitive processing. A “site-of-lesion” view based on anatomic levels inspired research to test competing hypotheses about the contributions of changes at these three levels of the nervous system. A “processing” view based on psychologic functions inspired research to test alternative hypotheses about how lower-level sensory processes and higher-level cognitive processes interact. In the present paper, we suggest that these two views can begin to be unified following the example set by the cognitive neuroscience of aging. The early pioneers of audiology anticipated such a unified view, but today, advances in science and technology make it both possible and necessary. Specifically, we argue that a synthesis of new knowledge concerning the functional neuroscience of auditory cognition is necessary to inform the design and fitting of digital signal processing in “intelligent” hearing devices, as well as to inform best practices for resituating hearing aid fitting in a broader context of audiologic rehabilitation. Long-standing approaches to rehabilitative audiology should be revitalized to emphasize the important role that training and therapy play in promoting compensatory brain reorganization as older adults acclimatize to new technologies. The purpose of the present paper is to provide an integrated framework for understanding how auditory and cognitive processing interact when older adults listen, comprehend, and communicate in realistic situations, to review relevant models and findings, and to suggest how new knowledge about age-related changes in audition and cognition may influence future developments in hearing aid fitting and audiologic rehabilitation.

Effects of aging on auditory processing of speech.

The focus of this paper is on the effects of age on speech perception, with reference to pertinent psychoacoustic findings. The difficulties of older listeners are related to the well-known effects of high-frequency hearing loss on speech perception in quiet, and to temporal processing declines not predictable from the audiogram that account for reduced ability to listen in complex, noisy conditions. We also discuss issues of research interpretation; e.g. the need for researchers and clinicians to be alert to the frequent confound between degree of hearing loss and age. The implications of age-related changes in auditory speech processing for future practice and research arc discussed relative to interactions between older individuals and their acoustic environments.

Cognitive aging and auditory information processing

Over the last decade, much research has been conducted to investigate why older listeners report more difficulty in understanding spoken language than would be expected given their degree of audiometric hearing loss. Of particular relevance to audiological rehabilitation is recent research on older listeners when they are engaged in complex tasks involving the auditory processing of naturalistic signals in realistic social and physical environments. Discourse epitomizes such activity. By understanding age-related and individual differences in perceptual and cognitive performance, we gain important insights into how hearing impairments influence activity and participation in context. In this paper, the problems of older adults as communicators in everyday life are illuminated by studies showing that auditory processing problems affect cognitive processing, Age-related problems in understanding spoken language arc exacerbated by perceptual stressors such as noise and by cognitive stressors such as memory load. It is argued that the significance of these processing problems during discourse depends on social-emotional factors, Therefore, goals for new signal-processing technologies designed for older adults who are hard of hearing can be framed not only in terms of improving signal audibility but also in terms of reducing stress on the listener during information processing. Furthermore, goals for therapeutic interventions can be framed in terms of reducing stress during information processing by modifying behaviors and physical and social environments to achieve the listeners goals.

The emergence of Cognitive Hearing Science

Cognitive Hearing Science or Auditory Cognitive Science is an emerging field of interdisciplinary research concerning the interactions between hearing and cognition. It follows a trend over the last half century for interdisciplinary fields to develop, beginning with Neuroscience, then Cognitive Science, then Cognitive Neuroscience, and then Cognitive Vision Science. A common theme is that an interdisciplinary approach is necessary to understand complex human behaviors, to develop technologies incorporating knowledge of these behaviors, and to find solutions for individuals with impairments that undermine typical behaviors. Accordingly, researchers in traditional academic disciplines, such as Psychology, Physiology, Linguistics, Philosophy, Anthropology, and Sociology benefit from collaborations with each other, and with researchers in Computer Science and Engineering working on the design of technologies, and with health professionals working with individuals who have impairments. The factors that triggered the emergence of Cognitive Hearing Science include the maturation of the component disciplines of Hearing Science and Cognitive Science, new opportunities to use complex digital signal-processing to design technologies suited to performance in challenging everyday environments, and increasing social imperatives to help people whose communication problems span hearing and cognition. Cognitive Hearing Science is illustrated in research on three general topics: (1) language processing in challenging listening conditions; (2) use of auditory communication technologies or the visual modality to boost performance; (3) changes in performance with development, aging, and rehabilitative training. Future directions for modeling and the translation of research into practice are suggested.

Use of supportive context by younger and older adult listeners: Balancing bottom-up and top-down information processing

Older adults often have more difficulty listening in challenging environments than their younger adult counterparts. On the one hand, auditory aging can exacerbate and/or masquerade as cognitive difficulties when auditory processing is stressed in challenging listening situations. On the other hand, an older listener can overcome some auditory processing difficulties by deploying compensatory cognitive processing, especially when there is supportive context. Supportive context may be provided by redundant cues in the external signal(s) and/or by internally stored knowledge about structures that are functionally significant in communication. It seems that listeners may achieve correct word identification in various ways depending on the challenges and supports available in complex auditory scenes. We will review evidence suggesting that older adults benefit as much or more than younger adults from supportive context at multiple levels where expectations or constraints may be related to redundancies in semantic, syntactic, lexical, phonological, or other sub-phonemic cues in the signal, and/or to expert knowledge of structures at these levels.Older adults often have more difficulty listening in challenging environments than their younger adult counterparts. On the one hand, auditory aging can exacerbate and/or masquerade as cognitive difficulties when auditory processing is stressed in challenging listening situations. On the other hand, an older listener can overcome some auditory processing difficulties by deploying compensatory cognitive processing, especially when there is supportive context. Supportive context may be provided by redundant cues in the external signal(s) and/or by internally stored knowledge about structures that are functionally significant in communication. It seems that listeners may achieve correct word identification in various ways depending on the challenges and supports available in complex auditory scenes. We will review evidence suggesting that older adults benefit as much or more than younger adults from supportive context at multiple levels where expectations or constraints may be related to redundancies in sema...

Processing speed and timing in aging adults: psychoacoustics, speech perception, and comprehension

Age-related differences are observed on many measures of both perceptual and cognitive processing, Indeed, strong correlations between basic measures of hearing and vision and age-related variations in intelligence have highlighted the powerful links between perception and cognition. In this paper, links between age-related differences in auditory temporal processing and slowing in cognitive processing are explored in an effort to illuminate how older adults listen to language spoken in challenging everyday conditions. Experiments in which the signal-to-noise condition is varied to equate listening difficulty for younger and older adults and experiments that simulate auditory aging in younger listeners provide evidence that at least some of the apparent age-related differences in cognitive performance during spoken language comprehension may be secondary to auditory temporal processing differences.

Temporal jitter disrupts speech intelligibility : A simulation of auditory aging

We disrupted periodicity cues by temporally jittering the speech signal to explore how such distortion might affect word identification. Jittering distorts the fine structure of the speech signal with negligible alteration of either its long-term spectral or amplitude envelope characteristics. In Experiment 1, word identification in noise was significantly reduced in young, normal-hearing adults when sentences were temporally jittered at frequencies below 1.2kHz. The accuracy of the younger adults in identifying jittered speech in noise was similar to that found previously for older adults with good audiograms when they listened to intact speech in noise. In Experiment 2, to rule out the possibility that the reductions in word identification were due to spectral distortion, we also tested a simulation of cochlear hearing loss that produced spectral distortion equivalent to that produced by jittering, but this simulation had significantly less temporal distortion than was produced by jittering. There was no significant reduction in the accuracy of word identification when only the frequency region below 1.2kHz was spectrally distorted. Hence, it is the temporal distortion rather than the spectral distortion of the low-frequency components that disrupts word identification.

Hearing impairment and cognitive energy: the Framework for Understanding Effortful Listening (FUEL)

The Fifth Eriksholm Workshop on “Hearing Impairment and Cognitive Energy” was convened to develop a consensus among interdisciplinary experts about what is known on the topic, gaps in knowledge, the use of terminology, priorities for future research, and implications for practice. The general term cognitive energy was chosen to facilitate the broadest possible discussion of the topic. It goes back to Titchener (1908) who described the effects of attention on perception; he used the term psychic energy for the notion that limited mental resources can be flexibly allocated among perceptual and mental activities. The workshop focused on three main areas: (1) theories, models, concepts, definitions, and frameworks; (2) methods and measures; and (3) knowledge translation. We defined effort as the deliberate allocation of mental resources to overcome obstacles in goal pursuit when carrying out a task, with listening effort applying more specifically when tasks involve listening. We adapted Kahneman’s seminal (1973) Capacity Model of Attention to listening and proposed a heuristically useful Framework for Understanding Effortful Listening (FUEL). Our FUEL incorporates the well-known relationship between cognitive demand and the supply of cognitive capacity that is the foundation of cognitive theories of attention. Our FUEL also incorporates a motivation dimension based on complementary theories of motivational intensity, adaptive gain control, and optimal performance, fatigue, and pleasure. Using a three-dimensional illustration, we highlight how listening effort depends not only on hearing difficulties and task demands but also on the listener’s motivation to expend mental effort in the challenging situations of everyday life.

Priming and sentence context support listening to noise-vocoded speech by younger and older adults.

Older adults are known to benefit from supportive context in order to compensate for age-related reductions in perceptual and cognitive processing, including when comprehending spoken language in adverse listening conditions. In the present study, we examine how younger and older adults benefit from two types of contextual support, predictability from sentence context and priming, when identifying target words in noise-vocoded sentences. In the first part of the experiment, benefit from context based on primarily semantic knowledge was evaluated by comparing the accuracy of identification of sentence-final target words that were either highly predictable or not predictable from the sentence context. In the second part of the experiment, benefit from priming was evaluated by comparing the accuracy of identification of target words when noise-vocoded sentences were either primed or not by the presentation of the sentence context without noise vocoding and with the target word replaced with white noise. Younger and older adults benefited from each type of supportive context, with the most benefit realized when both types were combined. Supportive context reduced the number of noise-vocoded bands needed for 50% word identification more for older adults than their younger counterparts.