Adults with mild hearing impairment: Measuring real-world hearing performance

Abstract

The World Health Organization recognizes acquired hearing impairment as the third leading cause of disability worldwide, with a mild hearing impairment the most prevalent. Between 1 in 3 and 1 in 5 adults have a mild hearing impairment, with prevalence rising with age. Studies of other age-related changes, for example in cognition and physical activities, suggest that declines in these functions may be exacerbated if hearing impairment is not addressed at an early stage.Few studies, however, have focused specifically on the implications of the early stages of hearing impairment in older adults. The research program in this thesis investigated the impact that a mild hearing impairment may have on an individual’s daily listening situations and if the most common intervention strategy – the provision of hearing aids – is beneficial. An initial systematized review found the limited research literature available indicated large variation amongst adults with mild hearing impairment in many aspects and in the weak correlations between current common audiological assessments and self-reported hearing difficulties. It also found some evidence that hearing aids could be beneficial for this clinical population but reports of hearing aid use, benefit and satisfaction were variable.The first empirical study in this research program utilized an international database to investigate hearing aid use amongst adults with mild hearing impairment. Retrospective fitting and data logging hearing aid use information was extracted from a total of 8,489 participants with bilateral fittings. Analysis of average hearing aid use showed that the participants with mild hearing impairment used their hearing aids as much as those with a moderate degree, on average 8.5 hours per day. These findings support the recommendation of hearing aids for adults with mild hearing impairment.A further need identified in the initial review was for evaluation of the real-world listening experiences and performance of people with mild hearing impairment. Such information has commonly been evaluated using self-report questionnaires. However, these require individuals to give global reports based on their memory of specific listening situations which may date back a number of weeks or months. To reduce the recall bias inherent in retrospective questionnaires, a methodology called ecological momentary assessment was applied in the subsequent studies in this thesis. Ecological momentary assessment captures data, via surveys, about participants’ experiences in real-time, in their natural environment. To date, ecological momentary assessment had been used in a small number of audiology studies. Therefore, the initial phase of the research in this thesis explored the feasibility and construct validity of ecological momentary assessment. Twenty-nine adults with mild hearing impairment (mean age = 69 years) answered daily surveys, over 2 weeks, about their hearing experiences in their everyday listening situations. The results showed good participant compliance, little participant burden and good feasibility. A comparison of subjective data (224 daily surveys of listening events) with objective data (environmental sound classifier data) indicated good construct validity.A total of 1128 individual listening event surveys were collected. The most common listening situations were conversation with three or fewer people or listening to television or radio, most often in the home with a speaker familiar to the participant. Participants reported, on average, very good speech understanding and low impact from their hearing difficulties during the listening events. However, while participants reported 100% speech understanding in just over half the listening situations, more than two-thirds of listening situations required effort, indicating that participants were performing well but expending effort. The study highlighted the wide range of variation of listening experiences amongst participants.The final study of the thesis focused on the differences that a short trial with hearing aids could make to listening experiences, using a single-subject design. Ten participants (mean age = 70 years) answered surveys about their hearing for a total of 4 weeks; 1 week without hearing aids, 2 weeks with and 1 last week without hearing aids. The surveys asked about the characteristics of the listening situations as well as the participants’ hearing performance. Comparison between the mean baseline and intervention phase hearing performance scores showed significant hearing aid benefit for speech understanding, listening effort, hearing difficulties hampering communication and enjoyment of listening events. Individual variation was again evident with nine participants showing small to large benefit from hearing aids and one not demonstrating benefit. This research program has given deep insight into the hearing performance of adults with mild hearing impairment and the potential benefits that hearing aids could bring to this clinical group. It also utilized a methodology still new to the hearing research field and showed how ecological momentary assessment can be a valuable tool for research and clinical practice in the future. The research program highlighted the value of collecting real-world data, be it from data-logging in hearings aids or real-time, in-situ surveys to fully explore the individual implications of mild hearing impairment.