Audio Technology Redefining Art
Wireless innovation to support a first of it's kind live theatrical production at LA's Union Station

January 20, 2014, by Ken DeLoria


Theatrical productions have been staged in many forms and venues over the years, ranging from traditional proscenium arch theatres to outdoor Shakespearian-inclined stages, from theaters-in-the-round to “black boxes,” and plenty more.

But I recently checked out something altogether different, a new avant-garde opera production entitled Invisible Cities that was staged inside the general transit area of Union Station in downtown Los Angeles.

The show, which ran twice nightly for about a month late last year, was the result of a cooperative effort among production company The Industry, the Los Angeles Dance Project, and Sennheiser, which worked closely with rental company Bexel ASG. The latter pair comprised the technical pivot point in this ambitious project, providing a transformation from initial concept into working reality of what was billed as the first “headphone” opera.

Putting It Together
The concept is radical and challenging. The staging of the Invisible Cities is based on the cast moving throughout the train station during the performance, while the audience members follow them as they wish. But first you have to find them…and that’s not easy.

Artistic director Yuval Sharon instructing the wireless-equipped cast at a dress rehearsal.

The opera is based on a 1972 novel by Italo Calvino. The narrative, accompanied by a musical score from an 11-piece live orchestra located in a remote room, took audience members on a multi-sensory journey throughout the terminal as the lead character, legendary traveler Marco Polo, described his quests to Emperor Kublai Khan.

Yuval Sharon is the artistic director who conceived of this work and brought it to life. When we spoke, he expressed a profound desire to blend everyday life with artistic expression. He talked about how the headphone experience would bring a new element into play. Initially, he was not fully convinced that headphones were the key so he explored, perhaps in the same vein as Marco Polo, and came up with a means of delivering this all-new form of theatrical content.

The Sennheiser- and Neumann-miked orchestra performing in a remote room.

Advanced wireless technology played a huge role in bringing the production to life. There were no loudspeakers; the audio was delivered to the audience via Sennheiser model HDR-120 wireless consumer headphones, and to the performers via Sennheiser 2000 series IEM systems, which handled in-ear monitoring duties for each of the singers and dancers, helping ensure their performances were in lock step with the musical score.

The EK 2000 IEM receivers, IE 8 earbuds and SR 2050 IEM twin transmitters were accompanied by a complex antenna system. Seventeen antennas for wireless mics, IEM and headphones were allocated among four concentrated locations throughout the station to achieve seamless RF coverage for both the performers and audience members.

Depending on the zone, model A 2003-UHF passive directional antennas were deployed with A 5000-CP circularly polarized antennas, effectively minimizing signal strength variations while eliminating multipath issues.

The “technology star” of Invisible Cities was the Sennheiser Digital 9000 wireless mic system, which delivered eight channels of uncompressed, artifact-free audio throughout the facility and captured the nuances of the libretto. The components of the Digital 9000 system included the EM 9046 digital receiver, SK 9000 beltpack transmitters and MKE 1 clip-on mics.

A fully digital transmission system, the 24-bit/96 kHz analog-to-digital conversion takes place in the transmitters. The clarity and sonic quality of the system was excellent, virtually identical to listening to wired mics in a studio control room, and it delivered rock-solid wireless performance in the notoriously tough RF environment that exists in downtown LA.

One of the four wireless antenna stations.

Sound designer Martin Gimenez specified a diverse collection of Sennheiser evolution mics to capture the orchestra’s brass and percussion as well as overall room ambience. For woodwinds and strings, including a harp, he called for several Neumann KM 184 small-diaphragm condensers, and for piano, selected a pair of Neumann U 87 Ai large-diaphragm condensers.

“Between the sonic immediacy of the headphone concept and Christopher Cerrone’s haunting orchestration, sonic transparency was paramount on our minds,” Gimenez says. “Having access to the entire range of Neumann and Sennheiser microphones proved vital and necessary in order to convey the amount of detail to each and every audience member.”

How It Works
Union Station is a busy, fully working transit station that host upwards of 30,000 passengers per day. And like it or not, for a month or so, the thousands of people who used the station were a part of the production, if only for a moment or two, as they made their way through the building. Most were completely unaware of what was taking place around them.

An actor outfitted with Sennheiser mic
and IEM.

I attended a dress rehearsal of Invisible Cities prior to its official opening. The concept could be called something like a “moveable production.” With your ticket comes the pair of Sennheiser wireless headphones. You put them on and wait for something to happen, perhaps feeling a little odd that you’re wearing a conspicuous over-the-ear set of headphones in a public place. But there are others around you with the same headgear—each performance accommodates 150 to 200 theatre-goers.

The cast members blend in with the travelers, especially at the beginning of the performance when they first appear, wearing ordinary street clothes. Then, out of nowhere, you hear a musical passage from the orchestra playing in a real room that’s hundreds of feet away. The sound grows in intensity, then diminishes, and then takes flight in various musical modalities. It’s an overture. This is the start of the experience.

Now a solo voice appears in your headphones, and you’re eager to see where it might be coming from. It’s by no means obvious. There’s a lot of space around you. You see a bustle in the crowd of your fellow headphone wearers, so you follow them for a while. Do they know where they’re going? Are they just guessing? Before too long you find the source of the voice. It’s a man in a wheelchair singing a poignant passage in operatic style, backed by the invisible orchestra.

Soon he is joined by another voice, a man dressed in typical transit station clothing, and wearing a shabby backpack. Again, it takes a while to realize where the second voice is coming from and who might be the vocalist. You visually explore the area and it’s very hard to separate the legitimate passengers in this rail terminal from those who might be cast members. The search is on for the tell-tale IEMs and headset mics, but both are well disguised. If you don’t have a close-up view of the performer, you cannot be sure if he/she is in the cast…or just a passenger wandering by.

The first actors have drifted away and new voices appear. Dancers augment the vocalists. Some are pushing brooms, wearing maintenance staff jump-suits. Others are exotic women in beautiful all-white gowns. They begin to appear in and around the large interconnected halls and the outside garden areas of the train terminal. Who do you follow? Where should your attention be directed?

The audience on headphones surrounding a facet of the performance.

And this is exactly what the producers want you to experience. A highly interactive event, that while scripted and choreographed, becomes a personal experience depending on what catches your attention, and what you decide to do about it. How you determine where you will focus on the different activities that are going on all around you is what makes it unique to each audience member.

Behind It All
The show could not be held without the foundational technology. The folks at Bexel, a company that is accomplished in serving complicated events, closed the loop between top-quality products and the successful deployment of them.

The wireless antenna cables were one of the numerous challenges of the project. They were routed to equipment racks in the control room where the Managed Antenna System components were located. MAS-500 Series equipment, which Bexel manufactures, was used to combine or distribute the various signals as needed. The use of ultra low-loss cables was impractical due to the public space issues, so the tech team had to be creative with amplification and signal routing to deliver the maximum allowable energy to each transmitting antenna and provide the cleanest signal possible for the wireless mic receivers.

“While the science is well known, and one in which Bexel has much experience, we had to apply our knowledge and expertise to an environment that required more than our customary methods,” states Andrew McHaddad, chief engineer for Bexel. “The greatest challenge was working in a public space with such a large, long-term installation. Cables and antennas had to be set up and torn down before and after each night’s performances, risking misconnected cables, incorrectly aimed antennas, and damage to cables due to pedestrian traffic or other forms of stress. The show’s audio department embraced these challenges with great professionalism and skill.”

Senior technical editor Ken DeLoria has mixed innumerable shows and tuned hundreds of sound systems with an emphasis on taming difficult acoustical environments, and he’s also the founder and former owner of Apogee Sound, which developed the TEC Award-winning AE-9 loudspeaker.

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Audio Technology Redefining Art