In recent years, the shift towards open-plan offices has been gaining momentum, with the aim of enhancing intellectual productivity through improved worker communication. A wealth of research has focused on the link between the acoustic environment and intellectual productivity. Yet, the intricate factors that bridge the acoustic environment with intellectual productivity remain elusive. This study endeavors to illuminate the pivotal role of impression evaluations in bridging the gap between the acoustic environment and intellectual productivity. Through a detailed empirical analysis conducted over six days in a real-world open-plan office, we investigated both the sound environments and the workers' impression evaluation during this period. Based on the results of the survey, an evaluation structure that represents the relationship between the acoustic environment and intellectual productivity in open-plan offices was studied using structural equation modeling. The results of the analysis showed that workers of multi-person work were more susceptible to the effects of acoustic environment than individual workers.