The acquisition of many perceptual skills proceeds over a course of days. However, little is known about how much daily training is needed for such learning to occur. Here we investigated this question by examining how varying the number of training trials per day affected learning over multiple days on two auditory discrimination tasks: frequency discrimination and temporal-interval discrimination. For each task, we compared improvements in discrimination thresholds between different groups of listeners who were trained for either 360 or 900 trials per day for 6 days. Improvement on frequency discrimination required >360 trials of training per day while learning on temporal-interval discrimination occurred with 360 training trials per day, and additional daily practice did not increase the amount of improvement. It therefore appears that the accumulation of improvement over days on auditory discrimination tasks may require some critical amount of training per day, that training beyond that critical amount yields no additional learning on the trained condition, and that the critical amount of training needed varies across tasks. These results imply that perceptual skills are transferred from short- to long-term memory (consolidated) daily, but only if a task-specific initiation requirement has been met.

Perceptual skills can be improved even in adulthood, but this learning seldom occurs by stimulus exposure alone. Instead, it requires considerable practice performing a perceptual task with relevant stimuli. It is thought that task performance permits the stimuli to drive learning. A corresponding assumption is that the same stimuli do not contribute to improvement when encountered separately from relevant task performance because of the absence of this permissive signal. However, these ideas are based on only two types of studies, in which the task was either always performed or not performed at all. Here we demonstrate enhanced perceptual learning on an auditory frequency-discrimination task in human listeners when practice on that target task was combined with additional stimulation. Learning was enhanced regardless of whether the periods of additional stimulation were interleaved with or provided exclusively before or after target-task performance, and even though that stimulation occurred during the performance of an irrelevant (auditory or written) task. The additional exposures were only beneficial when they shared the same frequency with, though they did not need to be identical to, those used during target-task performance. Their effectiveness also was diminished when they were presented 15 minutes after practice on the target task and was eliminated when that separation was increased to 4 hours. These data show that exposure to an acoustic stimulus can facilitate learning when encountered outside of the time of practice on a perceptual task. By properly utilizing additional stimulation one may markedly improve the efficiency of perceptual training regimens.

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The generalization of learning from trained to untrained conditions is of great potential value because it markedly increases the efficacy of practice. In principle, generalization and the learning itself could arise from either the same or distinct neural changes. Here, we assessed these two possibilities in the realm of human perceptual learning by comparing the time course of improvement on a trained condition (learning) to that on an untrained condition (generalization) for an auditory temporal-interval discrimination task. While significant improvement on the trained condition occurred within 2 d, generalization to the untrained condition lagged behind, only emerging after 4 d. The different time courses for learning and generalization suggest that these two types of perceptual improvement can arise from at least partially distinct neural changes.Thenotablylongertimecourseforgeneralizationthanlearningdemonstratesthatincreasingthedurationoftrainingcanbeaneffective means to increase the number of conditions to which learning generalizes on perceptual tasks.

In common practice, hearing aids are fitted by a clinician who measures an audiogram and uses it to generate prescriptive gain and output targets. This report describes an alternative method where users select their own signal processing parameters using an interface consisting of two wheels that optimally map to simultaneous control of gain and compression in each frequency band. The real-world performance of this approach was evaluated via a take-home field trial. Participants with hearing loss were fitted using clinical best practices (audiogram, fit to target, real-ear verification, and subsequent fine tuning). Then, in their everyday lives over the course of a month, participants either selected their own parameters using this new interface (Self group; n ¼ 38) or used the parameters selected by the clinician with limited control (Audiologist Best Practices Group; n ¼ 37). On average, the gain selected by the Self group was within 1.8 dB overall and 5.6 dB per band of that selected by the audiologist. Participants in the Self group reported better sound quality than did those in the Audiologist Best Practices group. In blind sound quality comparisons conducted in the field, participants in the Self group slightly preferred the parameters they selected over those selected by the clinician. Finally, there were no differences between groups in terms of standard clinical measures of hearing aid benefit or speech perception in noise. Overall, the results indicate that it is possible for users to select effective amplification parameters by themselves using a simple interface that maps to key hearing aid signal processing parameters.