More than 300,000 veterans with sensorineural hearing loss (SNHL) are fitted with VA-issued hearing aids (HAs) each year with the primary goal of improving their understanding of speech. Even older veterans without hearing loss experience a gradual decline in speech discrimination due to age-related changes in auditory function that compromise speech understanding in everyday environments. Neuroplastic reorganization within the central auditory system due to SNHL and aging contribute to these effects and compromise subjects' ability to process phonetic cues that are essential for understanding speech in noise. As a consequence, even when a HA restores high frequency signals to the cochlea in a patient with SNHL, speech understanding will remain suboptimal in the absence of rehabilitative perceptual learning.