This study investigated maturational changes in children's ability to discriminate the frequency of short-duration tone pulses. Frequency difference limens (DLs) were measured for digitally generated 1000-Hz tones with pulse durations of 200, 50, and 20 ms using a two-alternative, two-interval, forced-choice procedure. Participants were 16 5-year-old children; 10 children each in the age categories of 7, 9, and 11 years; and a control group of 10 young adults. Eleven of the 5-year-old children were unable to learn the experimental task. All children in the three older groups and the adults successfully completed the study. The five 5-year-old children who completed the task performed similarly to the 7-year-old children. All groups of participants showed an inverse relationship between duration of the signal and the size of the DL. The DLs at all three tone durations were significantly larger for the 7-year-old children than they were for the older children and adults. There were no significant differences in DL size among the 9-year-old, 11-year-old, and adult subjects at any tone duration. These findings suggest that the sensory and/or cognitive skills required to discriminate the frequency of brief-duration tones may not reach maturity until after age 7 years.

The present study investigated the temporal processing abilities of college students with diagnosed reading disorders. A behavioral test battery was used that involved discrimination of the pattern of presentation of tone triads in which individual components differed in either frequency or duration. An additional test involving measurement of frequency difference limens for long- and short-duration tones was also administered. The college students with reading disorders exhibited significantly higher error rates in discriminating duration patterns than the normal reading group. No group differences were found for the frequency pattern discrimination task. Both groups exhibited larger frequency difference limens with the shorter 20- and 50-ms tones than with the 200-ms tones. Significant correlations were found between reading ability measures and temporal processing abilities, specifically in word recognition and duration pattern processing, suggesting a relationship between lower level auditory temporal processing skills and decoding efficiency.

Cranford, Boose, & Moore (1990a) reported that many elderly persons exhibit problems in perceiving the apparent location of fused auditory images in a sound localization task involving the Precedence Effect (PE). In the earlier study, differences in peripheral hearing sensitivity between young and elderly subjects were not controlled. In the present study, four groups of young and elderly subjects, matched with respect to age and the presence or absence of sensorineural hearing loss, were examined to determine the effects of these two factors on performance with the PE task. Although significantly poorer performances on the PE task were found to be associated with both increased age and hearing loss, additional tentative evidence was obtained that the presence of hearing loss may have a relatively greater detrimental effect on the performance of at least some elderly subjects than it does on younger persons.

Six adult cats were trained to perform sound-localization tasks involving either single or paired sound sources. The behavioral response consisted of the cat releasing the left of two foot pedals when sound was perceived to the left of midline, and to release the right pedal, when the sound occurred on the right. In sessions with paired sounds, the effects of varying the time interval between the arrival of clicks from the left and right speakers were examined. The intervals used were 0.0, 0.2, 0.3, 0.5, 1.0, 2.0, 3.0, 5.0, 7.0, and 9.0 ms. For the group as a whole, the optimal delay interval for most accurate localization fell within the range from 0.5 to 2.0 ms.

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