Holman, Jack A.
(2020)
Investigations into the impact of hearing loss and hearing device fitting on daily-life fatigue.
PhD thesis, University of Nottingham.
Abstract
For many years, anecdotal evidence has suggested that people with hearing loss experience disproportionate levels of fatigue. The aetiology of fatigue associated with hearing loss was also thought to be uncomplicated. The basic energy depletion theory states that decreased audibility and fidelity result in an increased need for listening effort to maintain conversational performance. This, in turn, drains finite cognitive resources and results in increased fatigue. By the same logic, hearing device fitting should decrease fatigue by improving audibility and reducing the need for listening effort. However, recent research has not entirely supported this reasoning. Moreover, issues pertaining to the conceptualisation and measurement of fatigue have complicated efforts to measure its effects. Therefore, the research presented here was conducted to investigate the impact of hearing loss and hearing aid fitting on daily-life fatigue. Daily-life fatigue includes transient and long-term fatigue, and is contingent on the activities undertaken in everyday life.
To investigate what is already known regarding the aforementioned relationships, a systematic review of the existing literature was conducted. Although the available literature was relatively small, there was evidence to support a link between hearing loss and increased fatigue and, to a lesser extent, hearing device fitting and reduced fatigue. As fatigue is generally a result of activity, it was hypothesised that the relationships between hearing loss, hearing aid fitting and fatigue may be more complex than originally believed, due to the potential influence of hearing loss and/or hearing aid fitting on lifestyle. A narrative synthesis was conducted to examine the influence of hearing loss and hearing device fitting on activity levels, and consequently to determine whether any potential changes in activity could influence fatigue. It was noted that, to varying extents for work, social and physical activity, changes in activity level due to compromised hearing ability could potentially influence fatigue. In order to fully conceptualise the relationship between hearing loss and fatigue, previous relevant models were examined, and a new framework of listening-related daily-life fatigue was proposed.
To build upon the review results, the real-world impact of hearing impairment and hearing device fitting on daily-life fatigue was investigated using semi-structured interviews. Hearing loss-related fatigue affected most, but not all, participants. Fatigue was driven by effort in line with traditional theories, but also by negative emotions, a finding that has been less commonly documented. A wide and varied utilisation of coping strategies was exhibited. Hearing aid fitting was associated with reductions in fatigue, though the importance and magnitude of the reduction was unclear. The insights gained from the results provided new findings, support for previous research, and evidence for the different pathways involved in the proposed framework of listening-related daily-life fatigue.
Following the semi-structured interview study, an experimental study was carried out to investigate directly whether hearing aid fitting had any impact on fatigue. This was a longitudinal study of participants before, and at three time points after, first ever hearing aid fitting, compared to a control group who had no change in hearing aid status. This enabled analysis of both group and individual changes across time. In order to investigate the potential role of activity and other potential predictors, variables such as social activity, hearing handicap and need for cognition were also measured. Results showed that long-term general fatigue measures were not sensitive to any change after hearing aid fitting. However, hearing loss-related fatigue improved over time post fitting, with baseline hearing handicap score a significant predictor of hearing loss-related fatigue. While baseline social activity was not a significant predictor of fatigue, social activity scores did increase significantly over time in the intervention group when compared to the control group.
Overall, the thesis offers unique insights into the impact of hearing loss and hearing device fitting on daily-life fatigue, including the first ever longitudinal study to investigate experimentally the impact of hearing aid fitting on daily-life fatigue. The research has demonstrated the presence of hearing loss-related fatigue, the important role of activity in daily-life fatigue, and the positive impact of hearing aid fitting on fatigue and social activity. In light of the results, it is recommended that future research into daily-life fatigue takes account of activity, and that consistent terminology and measurement scales are utilised to address the correct components of fatigue.
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