Influence of individual factors and acclimatization on the perception of noise reduction settings

Hearing aid (HA) users differ substantially in their preference for noise reduction (NR) strength. This preference for and performance with NR processing are typically not correlated with each other (e.g. Neher 2014; Serman et al. 2016). In other words, HA users may prefer a certain NR setting but may perform better with another one.

The current study investigated the influence of individual noise sensitivity, HA experience and auditory acclimatization on the preference-performance relationship for different NR settings. A longitudinal study with three laboratory assessments distributed over a 12-week period was conducted. Groups of inexperienced and experienced HA users (N = 20 each) were bilaterally (re)fitted with test hearing aids in accordance with the NAL-NL1 prescription rule. Participants were selected based on an assessment of preferred NR strength performed at an initial screening visit (N = 100). An effort was made to ensure notable differences in preferred NR strength (‘NR haters vs. lovers’) in each group, and to match the two groups in terms of age and pure-tone average hearing loss. In order to investigate the effect of auditory acclimatization, half of the subjects were send home after the second laboratory assessment with increased gain while the other half remained on the initial gain prescription. A control group of experienced HA users (N = 10) completed the study with their own HAs.

Laboratory measurements were performed with four different HA settings: (1) unprocessed (amplification only), (2) single-channel NR, (3) directional microphones (DIR), and (4) DIR combined with single-channel NR. Preference was assessed using a spatially dynamic speech-in-noise task that required the participants to attend to a target talker while ignoring two concurrent distractor talkers. Speech understanding and recall were assessed using a listening span test (Neher et al. 2018). Further data on individual factors and subjective ratings of listening effort and satisfaction during the home trials were collected by questionnaires.

In this contribution, we focus on how preference for and performance with different NR settings change with HA use and auditory acclimatization, and how HA experience and individual noise sensitivity modulate these changes. Since rather new experimental procedures were applied in this study to determine the individual performance, test-retest data were determined with the control group without intervention at the same time intervals as the experimental groups.