Within a few sentences, listeners learn to understand severely degraded speech such as noise-vocoded speech. However, individuals vary in the amount of such perceptual learning and it is unclear what underlies these differences. The present study investigates whether perceptual learning in speech relates to statistical learning, as sensitivity to probabilistic information may aid identification of relevant cues in novel speech input. If statistical learning and perceptual learning (partly) draw on the same general mechanisms, then statistical learning in a non-auditory modality using non-linguistic sequences should predict adaptation to degraded speech. In the present study, 73 older adults (aged over 60 years) and 60 younger adults (aged between 18 and 30 years) performed a visual artificial grammar learning task and were presented with 60 meaningful noise-vocoded sentences in an auditory recall task. Within age groups, sentence recognition performance over exposure was analyzed as a function of statistical learning performance, and other variables that may predict learning (i.e., hearing, vocabulary, attention switching control, working memory, and processing speed). Younger and older adults showed similar amounts of perceptual learning, but only younger adults showed significant statistical learning. In older adults, improvement in understanding noise-vocoded speech was constrained by age. In younger adults, amount of adaptation was associated with lexical knowledge and with statistical learning ability. Thus, individual differences in general cognitive abilities explain listeners' variability in adapting to noise-vocoded speech. Results suggest that perceptual and statistical learning share mechanisms of implicit regularity detection, but that the ability to detect statistical regularities is impaired in older adults if visual sequences are presented quickly.

Auditory discrimination of speech stimuli is an essential tool in speech and language therapy, for example, in dysarthria rehabilitation. It is unclear, however, which listener characteristics are associated with the ability to perceive differences between one's own utterance and target speech. Knowledge about such associations may help to support patients participating in speech and language therapy programs that involve auditory discrimination tasks. Discrimination performance was evaluated in 96 healthy participants over 60 years of age as individuals with dysarthria are typically in this age group. Participants compared meaningful words and sentences on the dimensions of loudness, pitch, and speech rate. Auditory abilities were assessed using pure-tone audiometry, speech audiometry, and speech understanding in noise. Cognitive measures included auditory short-term memory, working memory, and processing speed. Linguistic functioning was assessed by means of vocabulary knowledge and language proficiency. Exploratory factor analyses showed that discrimination performance was primarily associated with cognitive and linguistic skills, rather than auditory abilities. Accordingly, older adults' discrimination performance was mainly predicted by cognitive and linguistic skills. Discrimination accuracy was higher in older adults with better speech understanding in noise, faster processing speed, and better language proficiency, but accuracy decreased with age. This raises the question whether these associations generalize to clinical populations and, if so, whether patients with better cognitive or linguistic skills may benefit more from discriminationbased therapeutic approaches than patients with poorer cognitive or linguistic abilities.

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