What the eyes can reveal about the ageing listening brain.

The ability to understand spoken language is a fundamental building block of successful communication. However, speech processing rarely takes place in ideal, laboratory-like environments. Instead, listeners must often contend with a backdrop of distracting noise or competing talkers (e.g., in cafeterias). Understanding speech in adverse conditions is known to rely on the integrity of domain-general cognitive functions (e.g., executive function, selective attention, processing speed). However, these higher-order cognitive capacities diminish with age. Owing to the combined effects of reduced sensory abilities (e.g., a hearing loss), an aging cognitive system, and the ubiquity of noise and other distractors in everyday listening environments, spoken language processing is often considered challenging and 'effortful' for older adults. However, the extent to which factors independent of hearing ability, namely attention and motivation, influence effortful listening in older adults remains unclear.

One way to examine the effect of listener-controlled processes on effortful listening is by manipulating the cost/reward trade-off and measuring online changes in physiological arousal. Intentional Listening (IL) refers to the strategic use of attention during listening; a process thought to be influenced by motivation. By examining IL during adverse conditions, this project aims to explore the cognitive and physiological mechanisms that optimise the ability to overcome everyday listening challenges for older adults. The need to address communication difficulties in older adults is more critical than ever before owing to a rapidly growing elderly population. A better understanding of the communicative barriers faced by older adults, and crucially the ways in which they can be overcome, will help to mitigate social isolation and improve quality of life.

This project will systematically test the predictions of a new Framework for Understanding Effortful Listening (FUEL) by teasing apart the complex interactions between IL, physiological arousal, and cognitive ability. The first aim of the project is to establish the relationship between physiological arousal and IL in young versus older adults using pupillometry. Pupillometry is an eye tracking technique that reveals moment-to-moment changes in physiological arousal and attention. The second aim of this project is to identify potential age-related differences in sustained attention by examining the time course of changes in physiological arousal during listening. The third aim is to uncover potential cognitive predictors of IL-based changes in physiological arousal by analysing individual differences in various cognitive abilities. Lastly, eye tracking techniques will be used to examine the influence of IL on the use of top-down (lexical-semantic) versus bottom-up (sensory) processing strategies in older adults. The visual world paradigm is now widely used in psycholinguistic research to investigate the precise timing of top-down processing operations (e.g., semantic integration) during spoken language understanding. Examining the effect of IL on the use of top-down processing strategies in older adults will help to elucidate the compensatory mechanisms that underlie IL-based changes in listening during adverse conditions.

In summary, findings from this project will elucidate the impact of IL for elderly listeners in adverse conditions and, in doing so, will contribute to our theoretical understanding of the cognitive and physiological mechanisms that underlie effortful listening and how these processes undergo change into late adulthood.

The most direct beneficiaries of the proposed work will be scientific researchers in the fields of hearing science and cognitive ageing. However, the theoretical and methodological knowledge gained from the proposed research will also benefit end-users in the wider society including clinical practitioners, educators, and more generally those with an interest in improving quality of life in the elderly population.

The need to address communication difficulties in older adults is abundantly clear in a rapidly growing elderly population. A better understanding of the listening challenges faced by older adults will help to prevent social isolation and reduce the likelihood of mental health issues. Reducing social isolation is especially pertinent in an age where widespread use of modern technologies (e.g., smart phones, social networking) has propagated a generational gap, engendering a sense of alienation in the elderly population.

Our research has the potential to encourage widening participation in higher education for older adults, like York's University of the Third Age (www.yorku3a.com). By exploring the mechanisms underlying effortful listening, this project aims to shed light on the ways in which older adults can take control of their learning and communication outcomes by optimising speech understanding in naturalistic environments. Societal impact will be achieved by addressing fundamental research questions such as: to what extent can elderly listeners use cognition to reduce communication difficulties in adverse conditions? Which cognitive skills best predict benefit from effortful listening in older adults? Answers to these questions are also likely to benefit other populations that experience listening difficulties (e.g., hearing-impaired individuals, non-native language speakers, individuals with learning difficulties). For example, listening strategies that will optimise the ability to learn a new language will be of interest to the increasing number of individuals who seek to acquire second language fluency (e.g., through higher education groups or online courses).

The PI's active involvement in the BSA Special Interest Group on Hearing and Cognition will serve as a platform for liaising with clinical practitioners, educators, and industrial partners on ways to incorporate the role of cognition during targeted interventions (e.g., speech perception training, hearing devices) for elderly and/or hearing-impaired listeners who struggle in noise. Findings from this project will help to signal a fundamental shift in focus from enhancing sensory acuity alone to the added consideration of cognitive factors that help to restore communicative function in elderly and/or hearing-impaired listeners. Raising awareness of the ways in which individuals can take control of their listening outcomes is not only a novel approach to the study of listening in adverse conditions, it will also likely help to promote a sense of empowerment in individuals who may otherwise find certain everyday listening environments (e.g., cafeterias, restaurants) intimidating due to excessive background noise.

Ultimately, addressing the barriers associated with cognitive and sensory decline in elderly listeners by promoting social interaction and effective communication strategies will help to improve quality of life in a rapidly-ageing society.