Auxiliary equipments: how they can affect hall's acoustical quality
Alessandro Cocchi, Giovanni Semprini and Ryota Shimokurao

Built spaces devoted to musical performances, like Auditoria, Opera Houses, and in general Theatres, were once designed with criteria derived chiefly from experience and only sometime from acoustical considerations about shape and materials: this happened in particular in Italy in seventeen and eighteen century. For instance, Richard Wagner designed the theatre in Bayroit based on musical considerations more than on physical considerations. In nineteen century Sabine began to consider the reverberation time as a mean suggestion to architects for a good listening quality, but only in the second half of the century other researchers found many acoustical parameters affecting the acoustical quality of an Opera House or a Concert Hall. Now it is possible, and in general requested, to design also multipurpose halls with acoustical instructions that allow us to avoid acoustical problems occurred in the past.
In any case noise coming from outside must be avoided, but nobody takes into consideration noise generated from machineries that are now more and more utilized for scenic effects and, during trials, for the contemporaneous utilization of bordering spaces: this paper will deal with this problem, showing in particular some recent example compared with the noise levels of a musical performance

Key words: opera house, concert hall, acoustical quality, noise level