Acoustic design of a long shape multipurpose and divisible hall

An huge industrial complex in Milan, constituted by many communicating buildings which cover an area of 14.000 square meters, is going to be transformed in a cultural centre dedicated to music, theatre and art expositions. The main hall is a long parallelepiped space (hall 1- dimensions: 130m x 19m x 22m) covered by a shed structure. The project previews that the hall will be divided in two “theatre style” halls (hall 2 - dimensions: 70m x 19m x 22m; hall 3 – dimensions: 50m x 19m x 22m), with sloped seating obtained by means of hydraulic platforms and, in particular conditions, like rock concerts or exhibitions the partition walls will be removed, the platforms will be led down and the hall will be used as single ambient. Hall 2 and mostly hall 1 are characterised by a very long shape, which causes problems connected with direct sound power and correct diffusion of sound density. A system of reflectors arranged over the public has been designed to reinforce the contribution of early reflections and to reduce virtually the volume of the halls in different configurations. The architectural acoustic methods have been integrated by electronic tools and a public address system, which permit to reach all listeners with a suitable dose of direct sound, elaborated in such a way as to create different virtual halls. This system allows to reach two important goal: the acoustic correction of an environment whose geometrical characteristics aren’t compatible with acoustics qualifications and an high flexibility in room use in accordance with customer requests.