Evaluating the concept of User Preference Fitting
We evaluated the concept of User Preference Fitting (UPF), where participants adjusted the hearing aid settings themselves. Subgroups indicated that UPF fittings can be very positive, resulting in improved performance, or very negative, resulting in poorer performance compared to prescribed settings.
Testing User Preference Fitting on experienced hearing-aid users
One way to individualise hearing aid fittings would be to give users a ‘steering-wheel’ or fine-tuning trimmers, enabling them to adjust the fitting parameters to their own preference in given listening environments (UPF). This was facilitated by means of a neural network. This network was trained to individual user preference settings in 11 different pre-defined environments – such as a post office or cafeteria - where two people were conversing in realistic background sounds.
18 experienced hearing-aid users participated in this study. In a field test, subjects were given access to both prescribed settings and self-adjusted settings in a triple-blind test design. Outcome measures were speech reception threshold (Hagerman sentences) in unmodulated and modulated noise; success or failure with the user preference fittings; subjective preferences (blinded settings), and themes from a semi-structured interview.
On average there were no differences in speech reception thresholds (SRTs) between UPF and Prescribed Settings. The blinded preferences of UPF versus Prescribed Settings did not show a pattern of preference for either of the two settings. But as a whole, the individual subjective preferences, SRTs, and interview outcomes revealed an interesting pattern of results.
One subgroup of subjects (about one third) demonstrated consistently better performance with the UPF setting compared to the Prescribed settings. This supports the idea that hearing-aid settings are important for this subgroup. Compared to the others, these groups found it easier to listen and accept the consequences of making adjustments to improve the fitting. However, what makes these subjects special is unknown. It could be that their absolute listening abilities were better – like skilled musicians - but this was not investigated in this study.
Another subgroup of the subjects (about one third) failed in their UPF setting, resulting in unrealistic neural network patterns. This led to poor performance and rejection of the self-adjustment fittings. They also expressed uncertainty about the adjustments - relying more on the prescribed settings – and appeared to be less confident about the decisions they were making.