By Steve Titus, B.A.Sc., P.Eng., and Kiyoshi Kuroiwa, B.A.Sc., P.Eng.
The Toronto Centre for the Arts (TCA) was originally built to offer a mix of smaller theatres, a recital hall, and one main stage for various performing arts presentations. This array allowed both the production companies and community groups to offer a range of shows to patrons. In the beginning, the main stage hosted major performing productions under the management of Livent Corporation, which filled the theatre on a regular basis.
After Livent ceased operating in 1998, the centre became the home of Dancap Productions, with successful runs of shows like My Fair Lady and Jersey Boys in the facility’s largest theatre. When the curtain fell on Dancap, the larger main stage sat mostly vacant while change in the surrounding community increased the demand for smaller theatre space.
Rather than allow the larger space to sit vacant, the decision was made to split the main stage into two smaller theatres. The two new theatres would better serve the community and be easier to fill. Led by architecture firm Diamond Schmitt Architects, renovations began in 2014 to divide the 1800-seat main stage into two: the Greenwin Theatre (with seating for 296) and the Lyric Theatre (with seating for 576).
Image © Aerocoustics Engineering
The project team was given one major limitation: the Toronto Centre for the Arts wanted to keep the original shell intact so the theatre could be returned to its original form if change was demanded again and a larger theatre was needed. Creating the two theatres at TCA within the existing shell of the original main stage was a first for all parties involved, and would require innovative thinking on a tight budget. From a design standpoint, this was no small feat—particularly when it came to acoustics.
In a performing arts centre, acoustics are integral. Placing two theatres within the confines of the main stage without being able to physically split the building posed numerous acoustical challenges. Not physically separating the theatres means there is always a path for noise and sound to transfer from one to another. A similar project was completed at the Queen Elizabeth Theatre in Vancouver in 2006—however, the two theatres in that building were structurally separated during the renovation process. This allowed for a simpler acoustical solution in providing adequate separation between the venues, but the structural challenges and expense involved in physically separating the existing venue were not viable within TCA’s budget constraints.
Primary considerations
For plays and performances in the space, optimizing speech intelligibility was a key goal. To accomplish this, the team focused on the following design parameters and set targets accordingly.
1. Distinctness
A technical indicator of speech intelligibility, distinctness (D50) is defined by the amount of energy arriving at a given position within the first 50 milliseconds of the direct sound compared to the overall sound energy. The design target is > 50 per cent. Speech intelligibility can be optimized in a room by ensuring low background noise and increasing the D50 (ensuring more early energy arrives at the listener position).
