Effects of Source-Specific Dynamic Range Compression on Sound Quality for Individuals With Hearing Loss

The purpose of this study was to compare the effects of source-specific (independent) and conventional dynamic range compression (DRC) on sound quality ratings among listeners with hearing loss when ground-truth signals are available to the compressor. Twenty listeners with mild to moderately severe sensorineural hearing loss rated the sound quality on different subscales for two types of signal mixtures: speech in music (Overall Sound Quality, Speech Clarity, and Music Pleasantness) and speech in noise (Overall Sound Quality, Speech Clarity, and Noisiness) at three speech-to-background ratios (SBR: -10, 0, +10 dB). Speech in music was a 10-second-long spontaneous speech excerpt with a duration-matched classical music excerpt. Speech in noise had the same speech signal mixed with speech-shaped noise. Conventional DRC applied a 50-ms release time to the mixed signals, whereas independent DRC applied a 50-ms release time for speech and a 2000-ms release time for music or noise before mixing. The control conditions included linear amplification applied to the signals before and after mixing. Independent DRC resulted in higher overall sound quality, music pleasantness, and lower noisiness ratings than conventional DRC, regardless of SBR. Independent DRC resulted in higher speech clarity ratings than conventional DRC at lower SBRs. The results are generally supported by acoustic metrics, indicating more effective compression and higher output SBRs, especially at lower input SBRs, and reduced across-source modulation correlations with independent DRC. These findings extend the literature on the advantages of independent compression of sound sources by demonstrating sound quality benefits across multiple sub-scales for listeners with hearing loss across music and noise backgrounds.