Sounding Off

“In my next life,” says Richard Olcott, FAIA, a partner at Ennead Architects, “I want to come back as the acoustician. The acoustician always gets his way.”

Projected on the wall in front of Olcott in his Lower Manhattan office are diagrams that appear to be CT scans. They are plans for a new concert hall now being built at Stanford University, and they have been marked up—electronically—by acoustical consultant Yasuhisa Toyota. In the course of designing the concert hall, Olcott says, he went through some 50 iterations, sending each (in the form of a Rhino model) to Toyota, who used proprietary software to determine how the room would sound.

Toyota, who prefers to keep his process secret, says only that the software has improved so dramatically in recent years that “until the last 10 years, we didn’t do a very good job.” He calls his earlier work “very primitive.”

But the use of sophisticated modeling software—including nonproprietary programs used by other firms such as Connecticut-based Akustiks and Kirkegaard Associates of Chicago and Boulder—means that the process of designing spaces where sound is important is largely data-driven. That means architects are likely to have less control of the overall design process than they might like. Still, the best consultants help apply data to realize the architect’s vision. “Yasu never tells you what to do,” Olcott says. “He looks at what you’ve done, and tells you how it’s working.”For Stanford, Olcott designed an oval hall with 844 seats, arranged in a vineyard style (that is, surrounding the stage and divided into groupings by low walls). Those walls closest to the musicians bounce sound back to them, which is why, Olcott learned, they need to rise from the stage at right angles, and reach a height of at least three feet. Other “vineyard walls” bounce sound around more generally, creating pleasing reverberation in the hall. “The idea,” Olcott says, “is that you should be hearing sounds coming from more than one direction—that’s what gives it the richness.”

But the oval design posed a problem: “Concave shapes concentrate sounds; you need convex shapes to disperse it,” Olcott says, explaining why he festooned the room with giant sails—actually panels of fiber-reinforced concrete, providing the necessary convex-ness. And what would those sails be covered in? “Yasu wants every surface to have a degree of bumpiness,” Olcott says, explaining that the bumpiness adds to the richness of the sound as it moves through the room.

And yet the bumps and ridges shouldn’t repeat at fixed intervals—which can cause echoes at particular frequencies. Olcott, taking off from a drawing by artist Robert Mangold, devised a random pattern of ridges, which were cut into the wall and ceiling panels (of fiber-reinforced concrete) by Kreysler & Associates of American Canyon, Calif., on a vast computer-numerical-control router. For architects, chance is just another way that acoustical consultants have influenced their designs.

Avoiding echoes was also a goal at Temple Beth Elohim, in Wellesley, Mass., where Kirkegaard Associates was the acoustical consultant. William Rawn, FAIA, the Boston architect, had designed a square sanctuary designed to take advantage of the woodland views—two of its four walls, nearly 70 feet long and 40 feet high, are glass. The effect is dramatic, but the danger “was that the sound would bounce back and forth” between the glass and other smooth surfaces, project manager Mark Penz says.

The solution was to ensure that parts of the interior walls were angled slightly. Other parts were covered in panels, from Akustik & Raum AG, consisting of a perforated wood veneer over absorptive backing.

Penz said that he looked at dozens of materials before deciding on the company’s Makustik panels (his options multiplied, he says, when construction costs declined after the financial crash in 2008). “When you’re right up against it, you can see the perforations, but from everywhere else it looks like wood,” he says. The sound system, also designed by Kirkegaard, uses speakers set into wooden screens, an aesthetic choice that is consistent with the building’s religious purpose. “You don’t want to be worshiping a loudspeaker,” Penz says. The speakers were also designed to project sound down, toward the congregation, rather than up to the ceiling, where it could get lost, Penz says.

At both the Bing Concert Hall and Temple Beth Elohim, the goal was to please large crowds. But the DiMenna Center for Classical Music, the Manhattan home of the Orchestra of St. Luke’s, posed a different acoustical problem: DiMenna is where the 37-year-old orchestra rehearses. As it was a rehearsal space without a full auditorium, there was a danger that there wouldn’t be enough distance for sound to travel before bouncing back at the musicians. For that reason, rehearsal spaces, says Russell Todd, a partner in the Connecticut consulting firm Akustiks, are always in danger of being too loud.

But at the same time Todd was making sure that the musicians could hear themselves, he had to make sure they couldn’t hear noise from outside—a danger given that the space is near the entrance to the Lincoln Tunnel. Luckily, they had a good starting point: the room, a former theater, was essentially a concrete bunker, and “heavy concrete construction is good for sound isolation,” Todd says. Within the existing concrete box, Akustiks and H3 Hugh Hardy Collaboration Architects designed a second concrete box that floats. The floor was a particular challenge: A new slab was poured atop the old one, then jacked up about 2 inches, leaving room for metal and neoprene springs between the layers. The springs dampen vibration from outside, with the metal ones handling the lower and the neoprene ones attenuating the higher frequencies, Todd says.

But what about the sound inside the room? The main determinant of how the room would sound—and look—were the four walls, which are made of masonry “hard cap” decorated with hundreds of vertical wood slats. The spacing of the slats was randomized, just like the grooves in the wall and ceiling panels at the Stanford concert hall and the wooden screens at Temple Beth Elohim. Behind the slats are velour drapes that can be raised or lowered, for additional sound dampening.

Overhead, the DiMenna room features a large skylight—making it a pleasant place for musicians to spend long hours rehearsing. But with a skylight, there was a danger of street noise leaking, and of sound from inside bouncing back too sharply. The first problem was solved by building the skylight out of two layers of glass, separated by 4 feet; the second by lining the skylight “walls” in acoustical panels.

In the end, the similarities between a rehearsal space and an actual concert hall outweigh the differences. “Musicians are the most important people in the room,” Olcott says of his Bing Concert Hall, scheduled to open in summer 2012. “You want it to sound good to them.” He adds: “You want them to say to other musicians, ‘Have you played at Stanford yet?’ ”