Polished Marble, Glass and Public Announcements

East of Maastricht, near where Germany, Belgium and the Netherlands share a common border, is the Dutch city of Heerlen. A commercial center since Roman times, Heerlen has become a publishing center: the Wall Street Journal publishes its European edition here. Like many European cities, Heerlen is a blend of old (a 12^th Century church), recent (Frits Peutz' Glass Palace) and ultra-modern architecture. The Parkstad Limburg theater complex, which includes two auditoriums and a 633-seat concert hall, is a stunning example. The entire complex was recently remodeled and updated from the inside out. New sound, lighting and staging systems were installed and the public areas of the building were completely remodeled.

The main hall's foyer is the architectural centerpiece of the complex. Two stories high, with a floor-to-ceiling window wall and marble-clad interior walls, it's vast, visually stunning—and highly reverberant, an aspect that until recently presented an impossible challenge for sound system designers. Before shows and during the intervals, more than a thousand people can be seen—and heard—mingling in the foyer. With the impeccably polished surfaces creating a giant echo chamber, the buzz of conversation rapidly escalates to a dull roar. However, the acoustical difficulties don't lessen the need for intelligible public address announcements to herald the start of the second half.

"In dealing with this central but acoustically very difficult space," says the theatre's technical manager, Rocco Malherbe, "we needed the spoken voice to be totally intelligible everywhere. But we also wanted an audio solution that could handle music properly, including occasional small concerts."

TM Audio, part of the Ampco Flashlight Group, found that solution in a pair of Iconyx IC24 Digitally Steered Array Systems from U.S. manufacturer Renkus-Heinz. The Iconyx arrays represent a new class of loudspeaker: they take advantage of recent advances in amplifier and digital signal processor (DSP) technology to control sound. Iconyx arrays are assembled from identical modules: three of them form an IC24. Each module contains eight co-axial loudspeakers, an eight-channel digital amplifier and eight channels of DSP. With a dedicated amplifier and processor for each speaker, the array can be configured to radiate one or more shallow beams of sound. The beams can be as narrow as 5° in the vertical plane and can be tilted up or down while the array's enclosure remains flush to the wall. The acoustic center of the beam (or beams) can be raised or lowered without moving the enclosure.

Digitally Steered Array technology provides a number of important sonic benefits in reverberant spaces like the Parkstad Limburg Theater foyer. More sound is aimed directly at the listeners, while less is free to bounce off the walls and ceilings. This increases the "direct-to-reverberant ratio," one of the key factors that allows listeners to identify consonants, and thereby distinguish words like "seats" from others, such as "beets," that contain similar vowel sounds.

Not only are digitally steered arrays like Iconyx more precise than older technologies such as large acoustical horns, they are much smaller. The IC24 arrays installed at Heerlen are 9 feet, 3.5 inches (2. 83 m) tall but only 6 inches (15.3 cm) wide and 7 inches (17.8 cm) deep. Because they can be mounted flush to walls or columns while aiming sound beams upward or downward to wherever people are standing or sitting, Iconyx arrays have minimal visual impact on the architecture. Finished in white to match the supporting walls, the two IC24s installed at the Parkstad Limburg Theater easily meet the architect's requirements for virtual invisibility in this striking open space.

Digital technology gives the tall, slender Iconyx arrays powerful, flexible control of sound. Careful attention to fundamentals of acoustic design has made sure that the sound is enjoyable and natural whether reproducing the spoken word or music. The high-performance co-axial loudspeakers have frequency response comparable to a high-quality home theater speaker. As in a home theater, subwoofers can add extreme low end impact if that's desirable, but the arrays are listenable without additional bass support.

TM Audio worked with the architects and project manager Malherbe to determine the mounting locations for the two Iconyx IC24 arrays. Next, they created a section view of the theater foyer in BeamWare, a Windows application that is used to design Iconyx arrays. The process is easy and intuitive, thanks to a well-design graphical user interface that hides complex mathematical calculations from the user. Once the Iconyx arrays are placed in a virtual space, the designer can define and aim the virtual sound beams by clicking the dragging the mouse. A display at the bottom of the window shows the predicted results—when they're satisfactory, the project is saved so that DSP settings can be uploaded to the Iconyx arrays at the job site.

The physical installation demands some expertise and the use of specialized tools such as laser levels and aiming devices: because of its highly precise control of sound, Iconyx demands comparable precision in the way it is mounted and aimed. Setting up the 24 DSPs in an IC24 array is the easiest part: just connect a computer and transfer information to the onboard firmware.

The new technology inside Iconyx has proven to be one of the most successful additions to a theater that strove for excellence in every aspect of its top-to-bottom renovation. "It was a key objective," Malherbe reports, "to create a theatre complex that can stage all the shows that are on the road in Holland—and be able to program anything anybody wants right here. We chose Iconyx specifically for its dispersion characteristics, its musicality and low architectural profile, and it's an excellent solution."