A number of studies have suggested that activating digital noise reduction in hearing aids may improve performance on tasks that are associated with cognitive capacity. This change in performance is attributed to a reduction in effort required for effective listening. This study from Desjardins and Doherty is one of the first to reveal these effects in a sample of participants with hearing loss.
Desjardins, J. & Doherty, K. (2014). The effect of hearing aid noise reduction on listening effort in hearing-impaired adults. Ear and Hearing 35 (6), 600-610.