Exploring the Effects of the Narrative Embodied in the Hearing Aid Fitting Process on Treatment Outcomes

There is strong evidence from other fields of health, and growing evidence in audiology, that characteristics of the process of intervention as perceived by the client (embodied narratives) can have significant effects on treatment outcomes, independent of the technical properties of the intervention itself. This phenomenon deserves examination because studies of technical interventions that fail to take account of it may reach erroneous conclusions and because clinical practice can put such effects to therapeutic use. The aim of this study was to test the idea that embodied narratives might affect outcomes in hearing aid fitting. This was achieved by carrying out experiments in which technical (acoustic) differences between alternative hearing aid fittings were absent, while providing test subjects with a strong contrast between the processes apparently applied to derive the fittings being compared. Thus, any effects of contrasting narratives could be observed, free of acoustical confounds. The hypothesis was that narrative effects would be observed.

A balanced crossover design was used, in which subjects received and evaluated two bilateral hearing aid fittings in succession. Subjects were deceived as to the true identical content of the hearing aid fittings being compared, but encouraged to believe that one fitting process was "interactive" and the other was "diagnostic" in character. Two almost identical experiments were undertaken: one with 24 experienced adult hearing aid users and another with 16 adult first-time users. Each hearing aid fitting was worn at home for 2 weeks, after which self-report outcome measures (Hearing Aid Performance Questionnaire, Hearing Handicap Inventory for the Elderly, and International Outcome Inventory for Hearing Aids) were administered. After the second test period, a short preference questionnaire was also completed.

Twenty of the 24 experienced users showed a clear preference for one or the other fitting, and their self-report scores reflected these preferences. Effect sizes were comparable with those typically observed for true acoustical contrasts. No order effect was seen in this group. In contrast, 13 of the 16 first-time users preferred the second fitting. Trends in the self-report measures were similar for this group but weaker than for the experienced users. In both groups, the reasons given for subjects' preference were predominantly related to sound, despite there being no acoustical differences.

This study suggests that the narrative embodied in a given fitting process can have a substantial effect on the perceived benefit of the treatment, independent of any acoustical differences, at least for experienced users. For first-time users, acclimatization seems to overshadow the purely narrative effect of any fitting process. In the future, research study designs should include steps to avoid narrative effects when technical parameters of hearing aids are the intended object of study. In clinical practice, the narrative is part of the therapeutic context, and one may design it for maximum beneficial effect.