Directional Processing and Noise Reduction in Hearing Aids: Individual and Situational Influences on Preferred Setting.

BACKGROUND

A better understanding of individual differences in hearing aid (HA) outcome is a prerequisite for more personalized HA fittings. Currently, knowledge of how different user factors relate to response to directional processing (DIR) and noise reduction (NR) is sparse.

PURPOSE

To extend a recent study linking preference for DIR and NR to pure-tone average hearing thresholds (PTA) and cognitive factors by investigating if (1) equivalent links exist for different types of DIR and NR, (2) self-reported noise sensitivity and personality can account for additional variability in preferred DIR and NR settings, and (3) spatial target speech configuration interacts with individual DIR preference.

RESEARCH DESIGN

Using a correlational study design, overall preference for different combinations of DIR and NR programmed into a commercial HA was assessed in a complex speech-in-noise situation and related to PTA, cognitive function, and different personality traits.

STUDY SAMPLE

Sixty experienced HA users aged 60-82 yr with controlled variation in PTA and working memory capacity took part in this study. All of them had participated in the earlier study, as part of which they were tested on a measure of "executive control" tapping into cognitive functions such as working memory, mental flexibility, and selective attention.

DATA COLLECTION AND ANALYSIS

Six HA settings based on unilateral (within-device) or bilateral (across-device) DIR combined with inactive, moderate, or strong single-microphone NR were programmed into a pair of behind-the-ear HAs together with individually prescribed amplification. Overall preference was assessed using a free-field simulation of a busy cafeteria situation with either a single frontal talker or two talkers at ±30° azimuth as the target speech. In addition, two questionnaires targeting noise sensitivity and the "Big Five" personality traits were administered. Data were analyzed using multiple regression analyses and repeated-measures analyses of variance with a focus on potential interactions between the HA settings and user factors.

RESULTS

Consistent with the earlier study, preferred HA setting was related to PTA and executive control. However, effects were weaker this time. Noise sensitivity and personality did not interact with HA settings. As expected, spatial target speech configuration influenced preference, with bilateral and unilateral DIR "winning" in the single- and two-talker scenario, respectively. In general, participants with higher PTA tended to more strongly prefer bilateral DIR than participants with lower PTA.

CONCLUSIONS

Although the current study lends some support to the view that PTA and cognitive factors affect preferred DIR and NR setting, it also indicates that these effects can vary across noise management technologies. To facilitate more personalized HA fittings, future research should investigate the source of this variability.