Excellent acoustics and a low RT? A case study of the recent renovation of the Kennedy Center Concert Hall, Washington, DC

In October 1997, the renovated Concert Hall at the Kennedy Center reopened to critical acclaim. The hall is designed on the shoebox model, but with an audience of 2759 and a volume of 250 cubic feet per person, its occupied midfrequency reverberation time was below the 2.0 s that is now considered fundamental to acoustical excellence. The musicians were also having difficulties hearing on stage. The acoustic redesign involved rebuilding the stage with reshaped walls, an acoustical canopy, resonant floor, orchestra risers, seating at stage sides and rear, and refurbished organ. Parterrre walls were added at orchestra level to increase side reflections. Since the ceiling could not be raised, reverberation was enhanced by building small reverberation chambers beside the stage and reducing seat count. Removing parts of the upper side balconies created an area near the stage where the sound field could develop without audience absorption. Changes also included echo control, new seats, and new stage HVAC system...