Computer model investigations on the balance between stage and pit sources in opera houses

The acoustical balance between the singer on the stage and the orchestra in the pit is typically found inside an opera house. The competition of the two sources is crucial, since in an opera the singer and the orchestra are performing at the same time. This topic of balance is receiving increasing attention in recent years, but several aspects are still to be clarified. The aim of this work is twofold: firstly the procedure for the acoustical qualification of the balance between the singer and the orchestra is investigated and secondly the means of controlling the balance at the design stage or during renovations is considered. For both tasks the study was conducted in a group of opera houses modelled within an acoustical CAD program. As regards the qualification of the balance this investigation compares the directional characteristics of two loudspeakers and of a dodecahedron omnidirectional loudspeaker in the emulation of a soprano during simulated room acoustics measurements. It is shown that, in order to emulate a soprano singer, the directional characteristics of the source on the stage are quite important. The control of balance was also studied and the work reserves a special emphasis to the case of historical opera houses. In fact, when such theatres are refurbished, the range of possible architectural interventions is often limited to the orchestra pit only, due to the heritage nature of the hall which prevents from any substantial change in the area of the forestage. For this reason it is important to investigate the effectiveness of such limited interventions in the pit, and this is done here by a detailed study of the effects on balance of some major changes of the orchestra pit only.