A new approach to hearing aid gain prescription for listening in noise: the NAL-NL3 Comfort in Noise Module.

OBJECTIVE

To describe the development and evaluation of the NAL-NL3 Comfort in Noise Module; a new algorithm for determining hearing-aid gain that is part of the NAL-NL3 fitting system.

DESIGN

Single-site multi-study design with each study and subsequent perceptual modelling informing refinements to module gain targets. Participants completed laboratory studies to investigate gain preferences and to evaluate the effect of the module on speech understanding in noise. Participants also completed real-world evaluations using a smartphone-based Ecological Momentary Assessment app with different brands of hearing aids.

STUDY SAMPLE: 83 adult hearing aid users with mild to severe hearing loss.

RESULTS

The new module selectively reduced gain (compared with the NAL-NL3 Prescription) by imposing a limit on the total loudness. Iterative refinements led to progressive increases in user preferences favouring the new module over the NAL-NL3 Prescription in noise with respect to listening comfort. Laboratory-based testing identified no detrimental impact on speech perception in noise.

CONCLUSIONS

Reducing the level of prescribed gain for hearing aid users in noise compared to in quiet improves comfort without significantly degrading speech understanding. This work supports the broader philosophy of the NAL-NL3 fitting system to provide specialised targets for different populations, situations and device technologies.