at the Symphony Hall Designed by
Skidmore, Owings & Merrill and
Pietro Belluschi along with acoustical consultants
Bolt, Beranek and Newman, its modern design is visually elegant both inside and out. A "cloud" of movable convex acrylic reflecting panels over the stage enables the acoustic space to be adjusted to suit the size of the orchestra and audience, while adjustable fabric banners around the auditorium can alter the
reverberation time from approximately one to two-and-one-half seconds. Architects created acoustic isolation of the performance space by constructing a building within a building. The outer building uses one inch thick structural glass as a curtain wall, with the next structural wall forming the back wall of the lobby spaces. Passing through a door leads to a hallway, bounded on one side by the lobby wall and on the other by the structural wall of the inner building. This continuous hallway acts as an acoustical isolator and is surfaced with sound absorbing material. However, the hall's large volume and
seating capacity initially resulted in less than ideal results.
Kirkegaard Associates completed acoustical renovations in 1992 at a cost of $10 million which resulted in substantial improvement. The modifications included: narrowing and shaping the walls above the stage to reduce the volume of space and increase useful reflections, replacing the cloud of reflector discs with a more effective array of curved rectangular panels covering a larger area and now computer adjustable, moving the walls of the floor-level seating inward to make the audience area narrower and more rectangular, adding aisles to replace the former continental seating, adding diffusing elements in various parts of the hall, and increasing the "rake" of the floor seating to provide better sightlines. In addition, the firm installed risers on the stage allowing musicians to both see and hear each other better. These and other improvements enhanced not only the acoustics but also the hall's beauty. ==Fratelli Ruffatti concert organ==