Tom Patterson theatre’s unique acoustical considerations

Photo by Scott Norsworthy

By Payam Ashtiani, P.Eng., and Doron Meinhard, B.Arch.

Along the banks of the picturesque Avon River in Stratford, Ontario, stands a significant new addition to the Canadian cultural landscape. Named for the festival’s founder, the Tom Patterson Theatre (TPT) is the Stratford Festival’s first new performance space in 20 years. Organizers had planned to dedicate it in 2020 to coincide with the 100th anniversary of Patterson’s birth; however, the pandemic delayed the tribute, and it is now slated to open in time for the 2022 season.

The $72-million project provides a state-of-the-art theatrical experience and replaces a similarly named venue in the same location. Originally constructed within a repurposed curling rink in the 1960s, the previous theatre had cramped seating, limited backstage areas, no space for patrons to mingle before and after the show, and was showing its age.

The new theatre is in many ways its opposite, designed not only as an attractor, and described by The Globe and Mail as having “some of the most beautifully detailed and well-sited public rooms in the country,” but it is also acoustically magnificent.

The horseshoe-shaped auditorium is the jewel set among an array of program spaces that are enclosed by a shimmering curvilinear glass and bronze veil. This organic shape blends into the riverside garden landscape and dissolves the line between indoors and out. The lobby, cafe, members’ lounge, education lab, and a secondary performance space called Lazaridis Hall are all light-filled spaces that face the landscape and river.

Design development of the Tom Patterson Theatre (TPT), a $72-million state-of-the-art venue. Image courtesy Hariri Pontarini Architects

Redesigning the new theatre

Throughout the building, acoustics were a top priority for the festival and its artistic director, Antoni Cimolino. The festival had tried to improve the acoustics in the original theatre, but mechanical noise, lights, and dimmers were an issue.

The new theatre recognized that being able to create moments of silence on stage could bring ‘magic’ to a performance.

The new auditorium is reminiscent of the original room in one respect: the innovative elongated thrust stage of the former TPT has been lovingly replicated and surrounded now by 615 seats in the three-quarter configuration. This unique performance space provides actors with runway-like access into the audience chamber. With only eight rows of seating on each side of the stage, the experience is immersive—with a more intimate connection between performer and audience than in traditional proscenium auditoriums.

With today’s focus on accessibility, the new auditorium is wider and longer than its predecessor and posed significant acoustical challenges. While it brings the audience closer, the acoustics of thrust stages are complicated by an actor facing away from large parts of the audience about half the time. In theatre, speech intelligibility is critical. The possibility of a performer facing away from the audience meant a considerable effort was needed to ensure a base level of speech intelligibility no matter where an actor was positioned. Speech intelligibility is affected by the ambient noise level in the room, and the complex reflection patterns of sound as it travels from the speaker to the listener.

The challenge was to deliver clear, intelligible speech to a location well behind the actor’s back—putting extra pressure on the acoustic performance of the space. While there is a sound system, the priority for the space is for unamplified spoken word, and its ability to reach every patron clearly—particularly when actors are at the other end of the thrust stage and facing away from the audience.

The new auditorium is reminiscent of the original room. The innovative elongated thrust stage of the former Tom Patterson Theatre (TPT) has been lovingly replicated and surrounded now by 615 seats in the three-quarter configuration. Photo by doublespace photography

First, the ambient noise level of the wood-lined room was designed to be quiet enough to allow for sounds to be heard clearly before fading into the background. This involves ensuring the noise from HVAC and other building systems were adequately controlled. The theatre is equipped with state-of-the-art, silent light-emitting diode (LED) lights to avoid any additional sound.

Second, the pattern of reflections had to be carefully designed. For good speech intelligibility, more acoustic energy would have to arrive at the listener in the first 50 milliseconds of sound arrival than after 50 milliseconds. This was achieved by approaching the challenge at two levels: macro and micro. At the macro level, the overall surface materials in the space were optimized to reduce the reverberation and minimize the sound that would linger past 50 milliseconds.

At the micro level, angled reflectors were designed and placed beneath each of the three catwalks above the stage to create a shorter path for reflected sound to reach the audience. Since the distance from the actor to the ceiling to the audience was too long, the reflectors intercepted the sound much sooner and reflected it back. The shape of the reflective surfaces was designed to direct early sound (<50 milliseconds) to the audience locations that needed it the most: behind the actor. If the geometry allows for those reflections to arrive in time, speech intelligibility is enhanced. Even with the actor at one end of the catwalk and facing away, this ensured an audience member on the other side would have a high level of speech intelligibility. Many design iterations for these reflectors were tested in a state-of-the-art sound lab to validate any subjective impressions of what the acoustic models and scientific values would be like to experience.

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