Effect of High Intensity Intermittent Sound on Compensatory Tracking and Mirror Tracing

Abstract

Many reported studies have been concerned with the effects of noise on performance (Kryter, 1950; Plutchik, 1959). Although some of the findings have been negative, there have been enough positive observations to warrant further study. In particular, very few studies have been concerned with the effects of high intensity intermittent sound on performance. To study the effect of such stimulation on compensatory tracking and mirror tracing was the purpose of this experiment. Findings of earlier work are somewhat inconsistent. At Tufts College (1942) it was found that the introduction of a 2-min. burst of noise during S's performance of azimuth tracking did not impair performance, nor was any appreciable effect on tracking found from 115-db noise as compared wich 90-db noise, with tasks that were changed at 15-min. intervals (Stevens, et al., 1941). In another study which required the tracing of a circular pattern by using two separate controls, no effect was found as a result of 90-db noise introduced for one-half hour (Viteles & Smith, 1946). In contrast, Broadbent (1954) found decreased efficiency of rapid recognition in a vigilance task (i.e., Ss have to watch for signals arriving at an uncertain time) as an effect of 100-db noise, but only for a more difficult task. High-pitched noise (over 2000 cps) at 100 db produced twice as many errors as high or low pitched 80- or 90-db noise (Broadbent, 1957). To account for these and other observations, Broadbent (1958) has developed an information theory type of analysis of the effect of noise on performance. He assumes that the nervous system acts to some extent as a single communication channel with limited capacity. Blocking that occurs in tasks as a result of noise may be due to interruption in the intake of information from one source, due to intake of information from some other, wich novel stimuli having a higher probability of passing the selective filter mechanism. Noise stress seems to produce an effect somewhat analogous to blinking, but within the central nervous system. This blink effect is of brief duration and increases in frequency as duration of noise lengthens. The effect is greatest for tasks where continuous attention is needed for new information (as in vigilance tasks) and where a high rate of information input occurs. This schema provides a framework that will be helpful in understanding the results of this