Effects of exposure duration and type of task on subjective performance and perception in noise

The influences of exposure time and the types of tasks on human perception and task performance have been investigated under a variety of noise conditions with differing level, spectral content, and behavior over time. Ten test subjects each completed 38 hours of testing over multiple days. Subjects were exposed to each of six background noise conditions over 20, 40, 80, and 240 minute trials. During the trials, subjects completed three types of performance tasks (typing, grammatical reasoning, and math tests) and answered questions about their perception of the indoor environment. Results indicate that the different exposure lengths used in this study did not have a significant effect on performance scores. Some influence of exposure time on subjective perception was observed, however; shorter time lengths combined with back to back exposures led to greater differentiation in perception. Significant differences in task performance between the different noise conditions were not observed, but differences in perception were found. Additionally, task performance was related to subjective perception; if subjects perceived the noise to be more tonal, they performed worse on all tasks. The performance results were not always negatively influenced by unfavorable quality perceptions, though. For example, as subjects perceived noise to be more roaring in this study, their typing scores decreased but reasoning and math scores improved.