Controlling reverberations without minimizing
In Minnesota, where hockey rules, there's a tradition at both the pro and college levels of loud fan participation. It's believed that loud arenas help produce a home ice advantage, something the University of Minnesota didn't want to give up. "The old arena was a converted field house, which was really loud," says Scott Ellison, Mariucci's program manager. "We wanted to bring the same level of crowd noise across the street to the new arena."
Sound consultants tried to convince the university athletic department to go with the acoustical treatment. "They gave us demonstrations of what treating the ceiling would do," recalls Ellison, "but it actually worked against their cause. The sound was better, but what really struck us was that the crowd response sounded so dull. We knew that once we put the treatment in, it would be nearly impossible to remove it if we didn't like the results. We decided against it."
At which point, the consultants as well as the university's internal A/V specialist agreed that there was no point in spending money on a good sound system that wouldn't be appreciated. The new $20 million, 9,300-seat arena received repainted loudspeakers from the university's old football stadium.
Missing the calls
"After the first season," says Ellison, "we resigned ourselves to giving up the home ice crowd advantage." The university quickly made available an emergency $150,000 for the necessary acoustical treatment.
Then Ellison talked to Bose. EMI, a Minneapolis Bose dealer, brought in Phil Nelson, a Bose sound design engineer. Nelson suggested that the money earmarked for acoustic treatment could possibly be better spent. "There were two problems with the acoustical treatment approach," says Nelson. "One, they would lose the loud crowd level; and two, once the treatment was installed, they'd be able to hear their old sound system. I told them they weren't going to like it." Nelson said there might be a way to improve sound quality, and in particular speech intelligibility, while retaining the loud crowd levels. "We told them that we didn't know for sure whether it could be done," recalls Ken Jacob, chief engineer of the Bose Acoustic Research Group, "but we would find out."
Maintaining excitement and intelligibility
In large spaces such as arenas, sound waves travel long distances from their source (a loudspeaker or a shouting fan) until they bounce off obstructing surfaces, such as walls or the ceiling. In small rooms, like living rooms, reflected sound comes back so quickly that the ear doesn't distinguish it from the original soundin fact, reflection adds to audio quality by creating rounder, warmer sound. In an arena, however, the sound takes long enough to reflect back that it may be distinguishable as an echo. In addition, reverberations (sound waves continuing to bounce back and forth while only gradually deteriorating) can muddy other sounds.
The Bose solution used four carefully positioned clusters of Panaray LT (for Long Throw) 4402® and 502®B speakers. The Panaray LT speaker projects sound in very narrow beams onto the audience. Outside the perimeter of each beam, acoustic energy falls off very quickly. This increases the amount of sound received directly by the listener's ear and keeps sound waves from reflecting off walls and other surfaces. The unique Panaray speaker design also minimizes overlaps between sound signals from different speakers. Overlaps can create hot spots, where sound levels are painful, or dead spots, where you have to strain to hear.
Defying conventional wisdom
As it turned out, Ellison didn't have to go on trust. Bose offered to let him hear what the Bose system would sound like before anything was installed. In a private Bose suite at the nearby International Association of Auditorium Managers' (IAAM) annual conference, Ken Jacob gave Ellison the opportunity to be one of the first to experience the Bose Auditioner® audio demonstrator, a technology that could create an image of the sound of the proposed system before installation in Mariucci. "It was amazing," recalls Ellison, "to sit in this hotel room and hear my arena. I heard it empty, half full, and with a full house. They even showed me what it would sound like in a particular seat."
In fact, the Bose team took Ellison on a complete tour of the arena, letting him hear sound in many different seats. "We were able to provide 75%-80% of the seats with very high speech intelligibility," says Nelson, "while significantly improving intelligibility in the remainder. And at a price of just over half of what they would have spent on acoustical treatment."
Ellison could hardly believe his ears. He called his boss, Mark Deinhart, Senior Associate Director of Athletics, and asked him to come over and listen for himself. But when Deinhart arrived, he heard even more: Bose told him that the installed system would sound as good as the simulationand Bose would guarantee the sound. In fact, they could even leave the existing system in place and compare the two. If they weren't completely satisfied, Bose would remove the new system at no cost to the university.
"With that kind of guarantee," says Ellison, "there was absolutely no risk to the university. We were able to get the deal approved very quickly."
The system was installed in less than six weeks. Working from midnight to 7 AM, the EMI team managed to complete the installation on schedule without disrupting ongoing sports activities. The debut was a Friday night hockey game in early October 1994.
Achieving the goal
The following Monday morning, the university A/V expert who had argued most strongly that Mariucci's sound couldn't be improved without acoustical treatment, walked into Ellison's office and said, "I've got to hand it to you. You stuck your neck out and you were right. It worked."