Adult auditory learning and training.

We describe a theoretical framework that distinguishes stimulus, procedural, and task aspects of learning, and we suggest that this framework may allow an improved understanding of acclimatization and late-onset auditory deprivation. We review the literature on learning after sensorineural hearing loss and after the provision of amplification. We then examine the possibility of using training to improve the speech-understanding skills of listeners with sensorineural hearing loss after provision of amplification. Here, we concentrate on techniques recently demonstrated to encourage the acquisition of non-native phonetic contrasts in second-language learners. We argue that there are three general principles associated with auditory learning and training: 1) the more complex the task, the longer the learning period required; 2) the greater the similarity between training and test tasks, the greater the transfer of training; and 3a) the more familiar the stimulus materials, the faster the subsequent learning. When training for speech identification in everyday life, maximizing the opportunity for the listener to cope with the acoustic variability found in natural speech, both within and between talkers, is important. We, therefore, argue that the third principle should be extended: 3b) the more the training set exemplifies the acoustic variability found within and between talkers, the greater the transfer to open-set speech identification in everyday life. Throughout the review, we show that individual differences in learning are observed in the rate of acquisition and in the level of asymptotic performance. We argue that it is possible to postulate modulators of learning that may account for some of these individual differences. Possible candidates for influential modulators are: 1) the history of hearing impairment--the longer the history, the longer the time taken to improve performance and, possibly, the lower the asymptotic level of performance; 2) the severity and pattern of hearing loss; 3) the degree of asymmetry in the hearing loss and its effect on the binaural organization of the hearing system; and 4) the level of patient adaptability and cognitive abilities, such as attentional control and short-term memory span.