This study examines the theatre placement of the band or musicians during early opera performances. This research is considered from the interdisciplinary points of view, for example, acoustic knowledge, and cultural customs of the time. Three countries, England, Italy, and France, where early operas were successful, are focused on. The arrangement of the bands or musicians is inferred based on various historical records such as plan views, libretti, scores, and spectator's diaries. As the results show, some similarities and differences exist between the three regions. For example, it was not the custom in early operas in the three regions to place the band or musicians in front of the stage. One can observe differences in the placement of the bands if they were not arranged in front of the stage. However, if they were positioned there, the pit was not set lower than the ground floor. From this research, the relation between acoustic knowledge and those of theatre construction and band placement could not be proved clearly. It is necessary to get more first historical sources to raise the estimated reliability in the future.