Abstract
Auditory thresholds were obtained during the course of a single, two-hour vigilance session from eight groups of 11 to 14 rated and non-rated Navy enlisted men each, to one of four signal rates: 1/hr., 2.5/hr., 7.5/hr., and 15/hr. Ss of each group were tested together in a dark, unlighted, noise-homogeneous room in close physical (and possibly tactile and vibratory) proximity but without visual or acoustic interaction. Each S wore earphones and pressed a microswitch to report single tones in trains of 12 successive tones ranging in 2-db steps from roughly 14 db below to 10 db above the average 5"s threshold. Results showed (a) a positively accelerated linear relation between auditory detection and log signal rate, (b) decrements of 1 to 10 db occurring early in the first half of the watch in all groups’ (and virtually all Ss’) performance at all signal rates, and (c) large individual differences permitting an arbitrary, significant separation of "better" and "poorer" performers.
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