Aging and auditory temporal sequencing: ordering the elements of repeating tone patterns.

In a series of experiments, we examined age-related differences in adults' ability to order sequences of tones presented at various speeds and in contexts designed to promote or to impede stream segregation. In Experiment 1, 32 listeners (16 young, 16 old) were required to identify two repeating sequences that consisted of four tones (two from a high and two from a low frequency range) in different order. In Experiment 2, 32 listeners were required to judge whether the two recycled patterns from Experiment 1 were the same or different. In Experiment 3, four young and four old listeners were tested on the tasks of Experiment 2 over an extended period. In Experiment 4, 16 young and 16 old listeners were tested with sequences that were not recycled and were composed of tones drawn from a narrow frequency range. Elderly adults were less able than young adults to distinguish between tone sequences with contrasting order, regardless of the speed of presentation, the nature of the task (identification vs. same/different), the amount of practice, the frequency separation of the tones, or the presence or absence of recycling. These findings provide evidence of a temporal sequencing impairment in elderly listeners but reveal no indication of age differences in streaming processes.