How to Tame Reverberant Rooms

Controlling ambient sound has taken on new importance, so here are some tips and techniques for integrators.>

Dan Daley
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To overcome this, custom line arrays were permanently installed in six to eight locations, depending upon the boundary parameters of an event. All the arrays are calibrated to act in a distributed system manner, directing the sound into the center of the space, away from the reflective surfaces, and doing so at lower volumes, which produces less energy and thus less potential for reflections.

To evenly cover the space, one or two line arrays usually end up being located on the wall behind the stage. Under other circumstances, this would be inviting feedback, since stage microphones would be pointed toward that back wall. However, in an example of how technology helps overcome acoustical issues, DSP on a Peavey Mediamatrix NION system controller is used to precisely dial out feedback via adjustments to parametric equalization and notch filtering.

“It helps that the nature of line arrays are not subject to the same level of feedback sensitivity as more traditional PA components, because the line array’s energy is dispersed more widely in a given horizontal plane,” says Haas, referring to what’s known as the line array’s “Q” value.

Interestingly, Haas is employing a similar solution in a corporate headquarters atrium project in Cleveland but where two separate sound reinforcement systems are being used: a series of localized small systems permanently installed in the atrium to deliver sound for a multimedia experience, and a large distributed system of line arrays that will be brought in for major corporate speeches or social events. In that case, the integrator on the project will be programming the system control for macros that recognize when two separate systems are simultaneously in use, adjusting EQ and time delays on both systems accordingly.

In Haas’ experience, audio, acoustics and architecture are inextricably tied together, and occasionally at odds with each other, particularly when aesthetics is at issue. That triumvirate has found some reconciliation with the use of a relatively new subsector of products: the compact line array, in which the line array design has adapted itself to smaller and smaller venues in the last three to four years. With ubiquity and this reduced size has come more and more choices for systems integrators. These seemingly reverse-evolutionary line array column products have created a new market category in the last couple of years, including Bose’s MA-12 and Renkus-Heinz’s ICONYX.

“The compact line arrays tend to integrate better into certain types of architectural designs, more so than hanging arrays,” says Haas, because they can conform to the lines of the space rather than simply be suspended by it, such as being attached to vertical columns or even to curved architectural elements, and camouflaged by being painted in a similar hue.

“We’re finding that we can use a column-type array with time-aligned, integrated subwoofers in about 90 percent of atrium-type installations,” Haas estimates. In fact, for the Cleveland project, Haas worked closely with the systems integrator to develop a custom lift, based on ones used to raise and lower screens into and out of furniture in high-end residential installations, out of the floor when needed, perhaps the ultimate camouflage.

“The goal is to find the solution that works acoustically, technically and architecturally for the client,” he says. “We have to work together to accomplish that.”

Bring the Noise

Joel Lewitz agrees, adding that, “We have to always be aware that it’s the relationship between the acoustical design, the sound system design, the space configuration and the client’s needs and ex
pectations that will result in the client’s satisfaction.” Lewitz, a principal in Rosen Goldberg Der & Lewitz, Inc. in the Bay Area, notes that not every project is predictable. For Maples Pavilion, home to Stanford University’s men’s and women’s basketball teams, the client wanted intelligibility but not at the expense of noise – the kind of noise that home teams in all sports venues want to hear behind them.

“You need a substantial level of intelligibility but not at the expense of making it too quiet, which can diminish the fan experience,” he explains. “We had to model it carefully so as not to let reverberation interfere with intelligibility but at the same time not deaden the room so much as to impact the excitement that the noise can generate.”

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