Fontana's recent work Speeds of Time involved positioning microphones and accelerometers (vibration sensors) in the clockworks of London's Big Ben, and playing the sound back from loudspeakers in a corridor of the Palace of Westminster below. Sound Island used hydrophones (underwater microphones) to gather sounds at the beach in Normandy, France, which were reproduced from speakers hung on the Arc de Triomphe in Paris.
As well as clocks and beaches, Fontana has long had an artistic affinity for bridges, treating these spans as giant stringed instruments. He has based past works on sounds generated by his beloved Golden Gate Bridge as well as New York's famed Brooklyn Bridge. His latest creation, Harmonic Bridge, taps into the resonances surging through the Millennium Bridge across the Thames River in London. Sounds that, at most, stay at the edge of people's consciousness are captured by accelerometers attached to the suspension cables, dynamically mixed by a programmable DSP device, then reproduced in two nearby public spaces: the vast Turbine Hall of the Tate Modern and the nearby Southwark Station of the London Underground.
Fontana has unusual requirements for loudspeakers. Meyer Sound's MM-4 miniature wide range loudspeaker, now a popular installation product, was created to meet Fontana's requirements for a work celebrating a new tramway in Lyon, France.
With assistance from global consulting and design firm Arup, who built the Millennium Bridge bridge, Fontana made some preliminary recordings of the bridge and then arranged a demonstration using an acoustic simulation of the Turbine Hall. Ben Borthwick, an assistant curator at the Tate Modern, was enthused by the proposal, although contractual restrictions prevented the museum from commissioning the work internally. At that point, the London Underground's Platform for Art program stepped forward to assume primary responsibility for organising and administering the project. "The people with 'Platform For Art' were the key in facilitating 'Harmonic Bridge,'" says Fontana. "It would not have happened without their involvement."
Engineers from Arup supervised the attachment of accelerometers that would remain in place throughout the exhibition. Resembling spark plugs, these devices make live transmissions of eight discrete sounds to the Tate Modern and also - after down-mixing from eight-channel surround to stereo - to Southwark Station via a dedicated digital telephone connection.
Inside the Tate Modern, sound installation and system calibration were entrusted to Autograph Sound Recording, a London-based company. To reproduce the full-range sounds of the bridge, Autograph engineers Lee Dennison and Scott George selected Meyer Sound MSL-2A high-power loudspeakers.
"We chose the MSL-2As for this project because of the varying dynamic range of the source signal and the sheer volume of the Turbine Hall," says George. "The system needed to excite the entire space while still maintaining the subtle nuances of the bridge. Also, the wide angle of dispersion meant the full coverage of the space could be achieved with fewer speaker boxes."
The MSL-2As are mounted two per side on girders and handrails above a rectangular space. A pair of legacy USW-1 subwoofers reproduces the deep bass hums and groans of the bridge.
"The range of sounds you hear is quite remarkable," says Borthwick. "Over time, you slowly decode the language of the bridge as you notice how sounds relate to the wind, the foot traffic on t
