Tehran University of Medical Sciences Auditory and Vestibular Research 2423-480X 0 0 2026 04 19 1501 1501 Hemanth Shetty University of Mysuru Srikar Vijayasarathy https://orcid.org/0000-0003-0064-3789 2025 11 03 2026 04 18 Background and Aim: To investigate if the effectiveness of digital noise reduction (DNR) in improving speech recognition scores and reducing listening effort in younger and older adults with moderate sensorineural hearing loss is associated with envelope distortion caused by the DNR algorithm used in hearing aids. Methods: Participants included 17 younger adults (18-45 years) and 20 older adults (51-70 years) with flat moderate sensorineural hearing loss (SNHL). The benefit of a modulation-based DNR algorithm was assessed using sentences (0° azimuth) presented in speech noise (180° azimuth) at +4 dB SNR. The Envelope Difference Index was calculated using the algorithm, and correlations between DNR benefits and envelope distortion were analysed. Results: DNR enhanced speech-in-noise recognition scores for younger adults, but it did not have the same effect for older adults. Listening effort, measured by final-word recall scores, improved significantly in both younger and older adults in the DNR group. However, there was no significant difference in EDI between the groups. No correlation was found between the magnitude of the envelope difference index and DNR benefits on speech recognition and listening effort in younger and older adults.  Conclusions: Digital noise reduction improved speech recognition in noise for younger adults but not older adults with moderate hearing loss, though both groups showed reduced listening effort, with benefits unrelated to signal envelope distortion. https://avr.tums.ac.ir/index.php/avr/article/view/1501