"What Bill Fontana has achieved is a truly hybrid and reactive sculpture of sound in time," says Rudolf Frieling, SFMOMA curator of media arts. "Crossing the bridge on the fifth floor activates a complex work in which the invisible structures of the architecture play as large a role as the random movements of visitors. It is a unique SFMOMA sound."
Nearly invisible, the MM-4XP loudspeakers are nested discreetly inside eight of the 254 small ventilation 'portholes' across one side of the curving wall. To generate source sounds, Fontana placed ten vibration sensors (accelerometers) on the building's rooftop heating and cooling pipes, as well as on the truss pedestrian bridge across the open atrium and on a nearby wooden floor.
"What I'm creating here is a dimensional shift using sound," explains Fontana. "The MM-4XPs are fading in and out in waves, filling the space, but with the signals slightly offset in time so it creates the illusion of the space expanding into a larger volume."
The MM-4XP loudspeakers work in conjunction with four ultrasonic emitters, each mounted on pan-tilt heads of the type normally used for moveable stage lighting. The emitters modulate ultrasonic signals to create limited bandwidth, extremely directional sounds that stream straight out like water from a high-pressure hose. Programmed to be in constant motion with assistance from Shane Myrbeck of Arup Acoustics, the emitters usually "splash" off surrounding walls but sometimes pass across visitors on the pedestrian bridge with startling effect.
"The ultrasonic emitters create interesting spatial sensations," observes Fontana, "but when the Meyers come in, they expand the space with a depth and richness the emitters don't have."
Organised by Rudolf Frieling, Sonic Shadows debuted on 20 November and will run through 16 October, 2011.
(Jim Evans)
