We have developed perceptual learning paradigms that drive this rehabilitative reorganization and significantly improve speech discrimination in new HA users. We now propose to test improved training paradigms in new and experienced HA users and older subjects with normal hearing. In Exp. 1 we will evaluate baseline speech discrimination in these populations using speech-reception thresholds (SRTs) in sentences, consonant-vowel-consonant nonsense syllable tests (CVC-NST), tests of tone-pattern discrimination, and tests of auditory short-term verbal memory (ASTVM). An analysis of the correlations of these measures will provide information about basic processes underlying impaired word and sentence identification. In Exp. 2 we will investigate the effects of CVC-identification training using performance-adapted masking noise. Based on our previous results, we anticipate that training will significantly improve CVC-NST scores. We will examine the extent to which training improves SRTs, tone-pattern processing, and ASTVM. In Exp. 3 we will train subjects in a tone-pattern identification task to evaluate the extent to which non-phonetic factors (e.g., familiarity with the computerized hearing tests, placebo effects of training, improvements in auditory attention, etc.) may contribute to training benefit. In Exp. 4 we will compare the benefits of training with single-consonant syllables with the benefits of two-consonant syllable training studied in Exp. 2. Finally, in Exp. 5 we will study the benefits of CVC training using consonant-specific noise levels adjusted to compensate for intrinsic differences in the discriminability of different consonants and compare them to the benefits of global adaptive training from Exp. 2. The experiments will clarify fundamental mechanisms underlying deficits in speech discrimination and ASTVM, provide insight into the nature of training-related improvements, and elucidate the parameters needed to optimize hearing rehabilitation.