The Rose Theatre Brampton in Ontario. Left: Shop testing of one of the 5,000 rubber pads placed under the structure to isolate it from train noise and vibration. John Swallow / Thornton Tomasetti. Right: Exterior view of the theater. Courtesy Jak Phreak / Wikipedia.
We provided acoustical consulting for the Rose Theatre Brampton, a 65,000-square-foot arts center that features an 870-seat main hall, a studio theater, a double-height lobby and a dramatic entrance rotunda. The multipurpose venue hosts theater, musicals, concerts, films, dance and corporate events. The structure was built atop an existing parking garage on a site only 20 meters from an active freight rail line.
Optimizing Auditorium Acoustics
The Rose’s horseshoe-shaped main hall includes a single shallow balcony designed for excellent sight lines and acoustic properties. Our design placed a priority on creating a space where the sound is intimate, warm, clear and enveloping, with excellent uniformity of sound distribution and reverberant characteristics. Each patron can clearly hear music and voice from the stage without amplification.
To achieve these effects, we controlled background sound levels to very low levels and placed sound-reflecting panels around the proscenium, side and back walls. Some of these panels reflect sound – from both the stage and the orchestra pit ─ to all areas of the audience.
Retractable curtains in both the main hall and studio theater provide variable acoustics: reverberation characteristics can be tuned for different performances, to a “dry” hall for speech and solo instruments or a “livelier” hall for music and musical theatre.
Noise and Vibration Control for Freight Trains
Freight trains on the nearby railway generate extensive air-borne noise and ground-borne vibrations that were perceptible at the site. Because the theater was built on top of an operational parking structure, it had to be supported on a transfer grid to distribute building loads to the garage’s existing columns. This ruled out the usual room-within-a-room option for blocking air-borne noise and posed a significant acoustical engineering challenge.
We developed a “floating” shell that envelopes the entire building to control exterior noise to the interior objection of RC 20. Exterior concrete pre-cast panels are resiliently supported and resiliently connected back to the building, while the entire roof slab is vibration-isolated from the structure, controlling train noise to meet the interior design objective.
To isolate the Rose from ground-borne vibration, we devised a system that placed 5,000 300-millimeter-thick rubber pads underneath the transfer grid to isolate the entire building. Measured vibration levels (and the noise radiated by vibrating surfaces) were controlled to well within the design objective.
Mechanical Noise Considerations
Building envelope considerations limited available space for mechanical equipment, forcing mechanical rooms to be adjacent to the performance spaces. Moving all stage HVAC above the stage house reduced noise, simplified ducting of supply and return and made the HVAC layout more efficient. High-quality duct silencers and mechanical-equipment isolation provided additional noise control for the stage HVAC and for two additional mechanical rooms, one on either side of the structure, that supply the rest of the building.
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