Client-Based Adjustments of Hearing Aid Gain: The Effect of Different Control Configurations

In Brief Objectives: Facilitating the fine-tuning of advanced hearing aids requires information about the acoustic environment. The concept of a “trainable” hearing aid may provide a more direct approach to hearing aid fine-tuning if the aid user is allowed to control the most important fitting parameters in his/her own acoustic environments. Design: In a laboratory study, the concept of self-adjustment of the gain-frequency response was tested by 24 hearing aid users using four different controllers with a limited number of control functions. Research questions focused on the reproducibility of the fine-tuned responses, the efficiency of the control configurations, and the effects of the control configuration on the end results of the fine-tuning process. Results: The subjects were able to provide systematic and reproducible feedback with respect to their preferences in different acoustic conditions presented audiovisually, achieving an average short- term test/retest standard deviation value of 2.8 dB. Two of the control configurations, featuring volume/slope and volume/bass/treble keys, were found to be more time-efficient and reliable, and were also preferred by 86% of the subjects. Although the control configuration did not have a strong influence on the end result, the gain-frequency response from which the subjects started their adjustments was found to have a significant effect on their preferred settings. Conclusions: Client-based adjustments of hearing aid gain provide a reliable method of individual fine-tuning. The results also showed that a biased correction of amplification is reached via self-adjustment within one session, which reduces the effectiveness of fine-tuning in a traditional clinical setting. A laboratory study in 24 hearing aid users showed that the aid user is able to control important fitting parameters for different acoustic environments in a systematic way. Test-retest reproducibility allows significantly different settings for different individuals and for different acoustical situations. The results show an unexpectedly large impact of the starting condition (baseline) on the preferred frequency response. This finding implies that fine tuning in a traditional clinical setting may be biased. For fine-tuning of advanced signal processing the concept of a “trainable” hearing aid may facilitate a more direct approach to hearing aid fitting.