Approximately 11 million hearing aids were dispensed worldwide in 2012, and of these over 60% were fitted to older adults. All were accompanied by a printed user guide containing information on hearing aid management and troubleshooting. The user guide should play an integral role in the transfer of information on hearing aids particularly as many older adults experience difficulty with aid management tasks, such as cleaning the device or changing the battery. However, it is only effective if it can be read and understood by the client. Many older adults have deficits in vision and/or cognition which may affect their ability to read and use healthcare materials, such as hearing aid user guides, and at least 30% have low health literacy. Health literacy refers to the ability to obtain, process, and comprehend health information and services. To-date there has been limited research on health literacy and/or the design and suitability of instruction materials in the field of rehabilitation audiology. Hence, the overarching aim of this thesis was to determine the appropriateness of currently available hearing aid user guides for older adults and to explore the potential benefits of designing hearing aid instruction materials based on best practice guidelines for health literacy.
The thesis is comprised of four studies. The first study analysed the content and design of a sample of printed hearing aid user guides to determine their suitability for older adults. Thirty six user guides from nine different hearing aid manufacturers were examined using a standardised assessment, the Suitability Assessment of Materials, along with four readability formulae. The results showed that hearing aid user guides are not optimal for older adults. Problems included frequent use of uncommon vocabulary, small text size and graphics, and high reading level.
The second study involved a review of the literature to determine features that should be incorporated into written healthcare materials and factors to consider in the design process when developing written instructions for a target audience of older adults. The findings were applied to the design and development of a set of written instructions for a self-fitting hearing aid and also informed development of the modified hearing aid user guide used in the final two studies of this thesis.
The next two studies explored the benefits of using best practice design principles in the development of hearing aid instruction materials. The studies involved 89 participants, with a mean age of 72 years, living in the community, and with no experience of hearing aid use or management. The aim of the third study was to investigate if a hearing aid user guide modified using best practice guidelines for health literacy resulted in superior ability to perform aid management tasks, compared to the user guide in the original form. Half the participants were randomly assigned the original user guide and half were assigned the modified user guide. All participants were administered the Hearing Aid Management Test, (developed for this research) which assessed their ability to perform seven management tasks (e.g., change hearing aid battery) with their assigned user guide. The regression analysis indicated that the type of user guide was significantly associated with the score on the Hearing Aid Management Test, adjusting for eight potential co-variates.
The final study sought to determine if the type of user guide (original versus modified) was associated with the ability of older adults to understand troubleshooting information and also to examine older adults’ preferences for user guides. It utilized the Hearing Aid Troubleshooting Test (developed for this research) which comprised seven items that assessed the ability of participants to find and comprehend information relating to troubleshooting. The study found that performance was significantly better, on all but one item, for participants assigned the modified guide. In addition, 80% of participants preferred the modified guide when shown both.
In summary, this research indicates that hearing aid user guides are not optimal for older adults which may impact on hearing aid outcomes and success. It highlights the association between the quality and type of hearing aid instruction materials and the ability of older adults to perform aid management tasks, and to find and understand troubleshooting information. It is therefore recommended that hearing aid user guides and other hearing healthcare materials be designed according to health literacy principles.