After administering the modified version of Weinstein's (1985) noise sensitivity scale on a population of 440 post-graduate students, a sample of 80 students, 40 of high and 40 of low noise sensitivity was drawn randomly. These Ss were then assigned on random basis to four high and four low noise sensitivity groups each consisting of ten Ss. By following multigroup design an attempt was made to investigate the effect of three kinds of noises on a multiplication task. Quantitative output and physiological energy expenditure inferred from the drop of fore-arm skin resistance, were measured. The significance of differences among the various group means were tested by Duncan's Range Test. Results indicated that due to adaptation, efficiency was not much affected in the case of low noise sensitivity Ss, but adaptation was not effective and efficiency on mental work was adversely affected in the case of high noise sensitivity Ss.