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TAMING OUR LADIES OF ETERNAL REVERB
 


NotreDame du Cap Basilica, Trois Rivières, Québec


The Oratory of St Joseph, Montreal

Canada possesses some of the world’s largest houses of worship – and Québec-based integrator Siscom says it has finally discovered the answer to the similarly giant-sized acoustic chalenges they pose.

Acousticians call them, affectionately, ‘Our Ladies of Eternal Reverb’ – the giant basilicas of the Catholic Church, ornate, historic buildings of such cavernous size that the reflected acoustic energy within their walls often makes intelligible vocal communication at over 25 feet distance all but impossible.

Two of Canada’s largest are the Oratory of St Joseph in Montreal, and the Notre-Dame-du-Cap Basilica at Trois Rivières, also in Québec. Both share many of the basilica’s typical architectural characteristics – dizzyingly high ceilings, stone columns and hard surfaces – a combination born of very different historical requirements that adds up, in today’s communications language, to long reverberation times and poor speech intelligibility.

Founded in 1979 by sound designer and acoustician Jean Giroux, integrator Siscom has installed sound systems in more then 350 churches in the last 25 years. The firm specialises in churches and what it describes as ‘acoustically challenging spaces’ and Giroux himself has led long-term audio projects in both the Oratory and Notre-Dame-du-Cap Basilica. “The problem for the voice in a basilica is the sound of the organ: they are antagonists,” he begins. “The resonance of the organ profits from the reverberating field, but the intelligibility of the word is compromised in a reverberating medium. You can’t use acoustic treatment because of the harmful impact that that would have on the resonance of the organ – it’s out of the question to decrease reverberation times; we have to work with this phenomenon and find other solutions to improve the intelligibility of the spoken word.

Siscom had been waiting since we began in 1979 for a real solution for these highly reverberant spaces we work with. Although we’ve seen developments in loudspeakers, crossovers, equalizers and DSP-based processors and measurement tools, combining DSP and computer capability with a high quality column speaker seemed like the way to go. Until recently column loudspeakers lacked the ability to control the sound in large, reverberant spaces – but we knew that technology was going to change that.”


In 2004, he and Siscom installation manager Hugues Dion saw a prototype of the ICONYX. “We immediately saw it as a promising avenue,” he says, “it provided the beam-steering capability we required and it was designed for music as well as speech, which was a very useful addition to the overall idea.” After Giroux heard the prototype ICONYX, he called Father Léo-Paul Nobert at the Notre-Dame-du-Cap Basilica. Designed by architect Adrien Dufresne, its dome is 125 feet high and the seating comfortably accommodates 1660 people. The original sound system comprised 26 column loudspeakers distributed in the seating.

EASE analysis of the Siscom team’s initial proposals confirmed the ideal location for a single loudspeaker and for the likely final solution of two units. Working with Renkus-Heinz Beamware software to set the aiming point, throw distance and lobe center, an IC24 was set up and ready in half an hour. “Walking the room with Father Nobert and head technician Benoit Marchand,” recalls Giroux, “everybody could feel the elation of the team to have finally found a solution for this challenging room. Several STI measurements made throughout the room proved that what we believed was true: the intelligibility was amazing.” The team finally settled on a pair of IC32s, which replace a large system of loudspeakers, amplifiers, crossovers, EQs, racks and cabling – and perform far better.

THE TAMING OF THE ORATORY

The Oratory of St Joseph Basilica, inaugurated in 1955, has a capacity of 10,000 people, measures 344 feet long by 255 feet wide, has walls of concrete and granite, a quartzite floor and an 85ft wide, 200ft tall dome. Its 3.4 million cubic feet space has an RT of 7.3 seconds, rising to 9 seconds at 500 Hz. Siscom’s audio system features networked zones that include the main sanctuary itself, the crypt, in daily use for services, and processions that move from the crypt via an external vault to the sanctuary.

The main sanctuary’s original distributed system of 40 horns was replaced with a greatly simplified system of just two ICONYX IC32 arrays and two IC16s. The result, says Jean Giroux, tames a previously impossible space for vocal intelligibility, without compromising the acoustics or aesthetic qualities of the basilica. “For so many years we’d watched manufacturers of loudspeakers improve their products, yet this kind of space remained unsolvable,” he says. “But ICONYX has finally made it happen in a remarkable way. It’s a major change of direction for us as integrators, too. Higher performances can be achieved with less equipment, less wiring and shorter installation time. You could say the technology we waited so long for is finally available.”


The Oratory of St Joseph, Montreal

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