Meeting Review, September 15, 2009
By: Scott Pfeiffer
On September 15, 2009 the AES Chicago Section met at Shure Incorporatedís corporate headquarters to hear Scott Pfeiffer talk about the design of the 143 seat 4000 square foot S.N. Shure Theater.
Mr. Pfeiffer is one of the principals at Threshold Acoustics LLC and was the acoustic consultant for the S.N. Shure Theater project.
The S.N. Shure Theater is a multifunction venue that has to accommodate audio and video presentations, product demonstrations, and live music performances. Apart from the challenge of designing a space for all of these functions, the theater had to be designed into the existing empty auditorium space without modifying the outside walls of the space, all without disturbing the Shure employees working around and above the site. To add to the challenges of the task, all of the mechanical systems for the headquarters building surrounded the space allocated for the theater.
Mr. Pfeiffer began the meeting by having a live jazz trio play to demonstrate the roomís natural acoustics and the reinforcement system performance. He then began his presentation by explaining that for the reasons listed above; this project was like building a ship in a bottle because both required the designer to fit within a predefined envelope of space, and a lot of patience.
Scott explained that the goal for the space was RC20, and that they were starting with a space that was RC57 before the work began. In the end they did achieve this goal with all mechanical systems operating but not without a lot of work along the way.
Traditional finish of room treatment such as perforated metal or curtains were out of the question, since the customer wanted a wood room to contrast with the glass and metal structure of the atrium around the theater. This requirement led to a picket fence type of treatment along the walls made of laminated slats. The slats are angled towards the stage with differing angle bevels on the leading and trailing edges of the slats. The proper pitch, spacing, and bevel angles were determined through research with a prototype panel that allowed for the rotation and variable spacing of the slats. In the end a progressive spacing was used that met both the acoustic needs, and architectural needs that a random spacing would not.
Since the outside walls of the room were not to be altered, a unique solution had to be envisioned where the mass of the wall would be interior to the room not exterior. This solution required both suspended wall sections and a floating riser floor to achieve the appropriate isolation. A notch filter at the resonant frequency of the slab ceiling, along with varied absorption on the ceiling, had to be implemented to prevent the performances in the space from affecting the people working in the office space on the floor above. Additionally a custom made venting system had to be devised that would reduce the significant noise entering the room through the HVAC ducts.
Mr. Pfeiffer concluded his presentation with measurements of the room which showed that they had exceeded their initial goals, and gave a demonstration of the roomís audio video system.