EFFECTS OF JET ENGINE NOISE AND PERFORMANCE FEEDBACK ON PERCEIVED WORKLOAD IN A MONITORING TASK

This study examined the effects of exposure to intermittent jet aircra ft noise (70 dBA or 95 dBA maximum intensity) and knowledge of results concerning signal detections (hit-KR) on performance efficiency and p erceived workload in a 40-min visual vigilance task. The noise feature d a Doppler-like quality in which planes seemed to approach from the m onitor's left and recede to the right. Perceptual sensitivity (d') was poorer in the context of noise than in quiet but only in the presence of hit-KR. The lack of noise-related performance differences in the a bsence of hit-KR most likely reflected a ''floor effect'' rather than some special relation between noise and feedback. When compared to sub jects performing in quiet, those who operated in noise were less able to profit from hit-KR, a result that may reflect the effects of noise on information processing. In addition to its negative effects on sign al detectability, noise elevated the perceived workload, as measured b y the NASA-TLX. This effect was robust; it was independent of the pres ence of hit-KR, even though hit-KR generally lowered the overall level of perceived workload. The results provide the initial experimental d emonstration that perceived workload is a sensitive measure of the eff ects of aircraft noise in monitoring tasks.