Clinical study of hearing instruments: a cross-sectional longitudinal audit based on consumer experiences

The objective of the present audit was to document improvements/changes in hearing instrument (HI) benefit in terms of use and satisfaction throughout the 1990s and compare the benefit in consumers fitted with analogue (A), programmable (P), and digital signal processing (DSP) HIs. The audit data are based on a questionnaire mailed to subjects fitted with HIs 3 to 4 months after the fitting, including questions concerning satisfaction with the HI, use of the HI, ability to manage the HI, and satisfaction with the overall services in the department. Information was obtained from 32,694 subjects (i.e., 71.2 per cent of those fitted with HIs throughout the last decade), with a median age at fitting of 78 years (range, 18-102), with a preponderance of females. No significant differences in age, gender distribution, and hearing instrument distribution were found between the respondents and non-respondents. The audit shows that there are no significant differences in any of the benefit parameters throughout the decade, irrespective of the introduction of P-HIs in 1995 and of the DSP-HIs in 1998. Thus, from the consumers' perspective, no changes have appeared in the last decade. A comparative analysis of the A-HIs, P-HIs, and DSP-HIs shows that among those provided with P-HIs and DSP-HIs, only 69.6 per cent (CI 68.1-71.0) and 65.5 per cent (CI 60.2-78.8), respectively, were very satisfied/satisfied with the HI, which is significantly less than the 73.5 per cent (CI 72.4-74.5) in those fitted with A-HIs. The daily/weekly use of all three types of HIs was similar. However, the group fitted with DSP-HIs was significantly less satisfied with the general services compared with those fitted with A-HIs and P-HIs, respectively. Based on these audit data, it is concluded that, according to the consumers, the outcome from HIs has not changed over the last decade, and a comparison between the traditional A-HIs with both P-HIs and DSP-HIs is in favour of the traditional A-HIs.