Fifty-six subjects performed a decision and data-entry task (for 40 minutes) to determine the influence of realistic noises on task performance. Implementation of a mixed two-by-seven complete factorial design was used to investigate the influence of noise on a) objective performance measures (number of questions answered, and errors) and b) subjective perceptions of the noises. The task involved both high and low complexity levels. Seven noises with different characteristics and spectra were investigated: continuous high frequency industrial, intermittent high frequency industrial, continuous low frequency industrial, computer printer noise, office noise, music, and white noise. Analysis of covariance performed on the task performance data showed a significant main effect of complexity and noise-by-complexity interaction. As expected, for all noise conditions, the high complexity condition was more detrimental to performance than low complexity. Also, Newman-Keuls test of the noise-by-complexity interaction showed that subjects who performed the high complexity task while exposed to printer noise were hindered more than subjects performing any complexity level under any other noise condition. Analysis of variance on the subjective rating data showed both main effects of noise and complexity to be significant. Regardless of the noise, the high complexity condition was consistently perceived as more difficult than the low. Subjects perceived the music condition to be more enhancing than the low-frequency industrial noise. All other noises were perceived to be similar. Subject gender was not found to have any significant effect on objective task performance measures or subjective perception of noise. / M.S.