Proper Systems Essential at 9/11 Memorial Events

The Shanksville, Penn., 9/11 memorial was held in a field near the crash site of Flight 93. Pittsburgh-based Northern Sound & Light used M2D Compact Curvilinear Array Loudspeakers, as seen at stage right next to a television cameraman.

The tragic events of Sept. 11, 2001, are certain to be memorialized in different ways and at different times in the future. No single day of ceremony, however, is likely to be more powerful than the first anniversary of those tragic events. On Sept. 11, 2002, moving memorial services were held in the Pennsylvania field where Flight 93 crashed, and in Washington, D.C., on the National Mall, close to the Pentagon.

The Pennsylvania location was not a traditional venue, and a huge crowd attended the Washington D.C. event, so both ceremonies posed audio challenges. In particular, the selection and use of loudspeaker arrays for the two events illustrate some recent advances in the audio field. Following is a look at the loudspeaker solutions used at the two locations and some expert opinions from principals involved with both events on the direction of such technology.


The Pennsylvania event was produced by Northern Sound & Light, a Pittsburgh-based company that has been in business since 1990. SRO spoke with company president Steve Raslevich Jr. about the event.

“Needless to say, producing the 9/11 memorial was unlike any job we've ever done,” says Raslevich. “It was really more of a mission than a job. The project was organized by the Somerset County Commissioners. Although they were getting offers of help from all over the world, this group wanted to restrict the vendors to Western Pennsylvania people. The event was being produced, after all, to give comfort to the families, not to get great notices from the press.”

As it turned out, the audio portion of the event was greatly impacted by weather-related problems. “The morning of the event, we were starting to place orchestral mics when an absolutely horrific wind swept through the area,” says Raslevich. “It seemed like a scene out of The Wizard Of Oz. I really thought that everything — chairs, music stands, mics — would fly off the stage and never be seen again. Chairs were actually blowing away. By the time the event got started, the wind had died down a bit, but not much. We high passed [filtered] the signals to remove as much of the wind from our broadcast as possible, but there's only so much high-pass you can apply before you start to cut into the body of the signal, so some of the wind sound had to make it on-air.”

Northern Sound & Light used Countryman mics for the podium and Shore and Sennheister mics for the Johnstown Symphony Orchestra, an ensemble based close to the Shanksville site. Northern Sound & Light had provided audio services for the Johnstown Symphony in the past. But for this event, the company provided more than just audio support.

“We put together a detailed CAD design of what the layout would look like, down to the placement of each chair,” Rasvelich says. “We donated these design services, and then we were hired to handle the lighting, staging, and audio. We also donated one of our mobile stages as a press platform.”

Other audio performances at the event included selections by the 2nd Marine Aircraft Wing Band, stationed in Cherry Point, N.C., and brief speeches made by former-Pennsylvania Governor Mark Schweiker, Homeland Security Chief and former-Pennslyvania Governor Tom Ridge, and Sandy Dahl, the wife of Flight 92's pilot.

The emotional intensity surrounding the event forced Raslevich's crew to play catch-up as the day approached. “It was very difficult,” Raslevich says. “This was a fairly large event that was being coordinated by a group that had every good intention but no experience in putting on an event the size of this one, which was expected to be held before a crowd of about 20,000 people. Simple questions, like ‘Where do the chairs go?’ were not thought through ahead of time.”

The Meyer Sound M2D Compact Curvilinear Array Loudspeaker system produced the proper sound for the memorial event.

Northern Sound & Light ended up assuming responsibility for the staging of the event. “We were setting up the decking, placing mics, focusing lights, setting up the speaker array, with very little time,” Raslevich recalls. “For example, we couldn't wire the stage until the chairs were delivered, and they were very late in arriving. But it really was an honor for us to take our experience and help put this day together for the families.”

On-site sound was delivered through a Meyer Sound M2D Compact Curvilinear Array Loudspeaker system. After a friend recommended the Meyer Sound system to Raslevich, Northern Sound & Light purchased one in July 2002. “Up until this year, we'd been using our own proprietary cabinets for front-of-house,” says Raslevich. “That was working fine, but we had made the decision to go for a name-brand box this year. The M2D arrived at our facility just a few days before a major event we were producing. Literally half the rig was taken to the job site in its original packaging — everything snaps into place in minutes. We had to tweak the time alignment, but that was all. The system sounded like a million bucks.”

Designed for mid-size applications that require tight vertical-pattern control with long throw, the M2D Compact Curvilinear Array Loudspeaker uses a complex crossover design. At the lowest frequencies, both 10in. cone drivers combine to reproduce powerful, coherent bass. In the mid-frequencies, the crossover feeds only one of the two drivers. This technique eliminates interference between the drivers that would otherwise occur at shorter wavelengths and maintains optimal polar and frequency response characteristics. The M2D-Sub compact subwoofer extends the system power bandwidth and frequency response down to 35Hz.

The system worked smoothly in the Pennsylvania field during the memorial event. “We were honored to work on the 9/11 event,” says Raslevich. “As Pennsylvanians, we were hit hard by the events of the day. Having the opportunity to help produce a memorial intended to honor the victims and their families was an experience none of us at Northern Sound & Light will ever forget.”

Washington D.C.

The nation's capital was having its own day of remembrance near the Pentagon. Metro Events, an event-production company based in the Washington, D.C., area, was asked to produce the memorial event, held in the open-air Sylvan Theatre, located on the grounds of the Washington Monument. Thousands of people attended the event, which featured several speakers and performances.

For Metro Events president Les Slaybough, helping the airline professionals in attendance pay respects to victims of the disaster made this one of the more meaningful projects with which the company has been involved. “We've done a lot of high-profile events in this town over the years, but this was something the public could really relate to, even more than some of the First Amendment free-speech rallies that we often help produce at the nation's capital,” Slaybough says. “It was a very moving event, both uplifting and depressing at different points, but it was definitely a morale builder for the airline workers. It felt good to be a part of it.”

Metro Events used eight SPL-td1 loudspeakers from Sound Physics Labs. The loudspeakers worked well for the windy conditions on the day of the memorial. “One of the nice things about the [SPL-td1] box, in a windy environment like we had that day,” says Slaybough, “is that we can contour the box with a Brooks Sirens mini drive that can take care of the problems the wind generates by blowing across the microphones.”

Front-of-house view of the audio setup created by Northern Sound & Light.

Boundary compliancy may not be the Holy Grail, but it is one of the most important aspects of contemporary speaker design. Slaybough is very impressed with this aspect of the SPL-td1 array. “The sound from the speakers doesn't overlap, like in traditional arrays,” he says. “With their tight pattern, you can place them side by side, and they don't overlap but stay nice and smooth across the whole area. They hold the pattern and project forever, which is especially good in an outdoor environment. And it almost doesn't matter where you are in the audio field — whether it's 10ft. or 300ft. back — the sound is smooth and clear and the fidelity is unreal.”

Designed by Thomas Danley, director of acoustical physics applications at Sound Physics Labs, the SPL-td1 employs newly patented technology that combines the outputs from multiple drivers to drive a single horn, allowing each driver to operate in its own frequency range. According to Brad Skuran, president of Sound Physics Lab, the result is a flat-frequency response that is automatically time-phase correct. Skuran also credits the Unity Summation Aperture design element of the SPL-td1 as a major reason for its success at events like the Pentagon memorial.

Elevated standards in home-theater design have raised the bar for all audio applications, including venue production. “Advances in the last 20 years have brought the level of audio fidelity in live venue performances to a very high level,” says Slaybough. “Ninety percent of event attendees are not audio engineers. They don't understand what's going on behind the scenes — they normally don't have any knowledge of physics and acoustics, and they really don't care. But they are aware of what does and doesn't sound natural to them. Delivering natural and even audio coverage to a large amount of people in any given area is always a huge challenge, and I think the SPL-td1 [system] is perfect for this job. Its boundary-compliant design allows you to deliver audio to all spectators in the audio field.”

Airline professionals pay their respects to victims of the 9/11 tragedy at the Washington D.C. memorial event.

Audio experts, including Slaybough, are enthusiastic about these developments because they offer hope that event speakers might someday catch up to the rapid — usually digital — advances in other portions of the audio world. Speakers remain the wild card in this equation, particularly because real-world factors routinely intrude on their performance. Awkward design spaces, difficult climate circumstances, and the inherent problems associated with attempting to design speakers that will throw identical audio patterns to thousands of people make the evolution of speaker arrays a vexing challenge. Event producers are clearly pleased with the performance of some recent entries into this field, as the use of such technology during the two 9/11 memorials clearly demonstrates.

Gary Eskow is a composer and journalist who lives in Central New Jersey. Email at