Performance, two performer's wearing ultrasonic speakers masks.
The unique characteristics of the ultrasonic speakers technology allow the sound to be transmitted in a narrow directional beam, and for the sound to be reflected from the architecture of the space, highlighting the unique features of the surrounding.
Ultra-Sonic-Face is a performance piece in which the speaker is worn on the face by the performer as a mask, cultivating a new sense of space based on auditory perception. The unique qualities of the performance, based on ultrasonic speaker technology, separate the sound source and the sound which circumvents our familiarity with natural laws and allows the audience to soak in doubt.
Performed w\ thingyi jiang Sound processing by Valentine kellein. Part of the group exhibition of ArtScience in Het Hem
Het HEM Art center, Zaandam, NL
directional speaker \parametric speaker\ultrasonic speaker allows to create narrow beam of sound in the space and to direct the sound to a specific person or to create reflection of sound from a specific object in the space. If, for example, a standard speaker acts as a light bulb, the sound scatters in every direction, the directional speaker is like a laser, the sound moves straight and is reflected when it hits objects in space. Using this method, it is possible to create a spatial sound, without using a complex sound system. Furthermore, contemporary sound technologies that are accessible to the public do not make it possible to really move sound. These create, through complicated calculations, the illusion that the sound comes from a different source than it actually come from.
The principle on which the speaker works is sound from ultrasound. By using transducers arrays, the resonance frequency of the transducers used is 40Khz, the sound is broadcasted on a carrier wave of 40Khz using AM modulation, colliding with a non-linear medium like air or object creates a phenomenon of demodulation that makes the sound hearable.
"This comes in contrast with the intuitive tendency to get closer to the source of sound, to our fellow viewers, to unite and to share our mutual experiences. The dissonance that arises through the work exists but is made more evident through the individual perception of sound"
The modern directional speaker began with Joe Pompei at the MIT Media Lab. Large parts of his 2002 PhD thesis go straight over my head, however there is a lot of good information in there, including a summary of previous research into directional speakers (spoiler: the military did a lot of work with sonar), and a human-readable summary of the math.
Pompei combines two ideas to produce a directional speaker. First, sound waves are directional if the width of the wavefront is much larger than the wavelength. Middle-C (262-ish Hz) has a wavelength of 1.32m, so if a speaker were, say 10m wide, you might be able to get a directional wavefront from it. Ultrasonics however have much smaller wavelength - about 8mm at 40kHz - so reasonably sized speakers will produce a directional wave front.
Second, ultrasonic sound waves will demodulate in air. The resulting audible sound is much quieter than the ultrasound that generates it.
As part of my practice I use this speaker as a mask on my face, this allows me not only to fully control where the sound will come from in space, but also to hear the space itself without seeing it. When the speaker is directed at a wall, one can hear the reflection coming from the wall and place the wall in space...it gives the power of sight without any need for light. The same technic that allows bats to navigate in pitch-black spaces. I perform with this set up on two different occasions: “poly ability”(2021) multiply media performances, in collaboration with Leon Robbi and Tingyi Jiang made during two weeks residency program in cloud dance lab, in “Sculpt” (2021) with Tingyi Jiang in the exhibition Nature Melancholy of the Anthropocene and in HET-HEM "Ultrasonic face"(2022) with Tingyi Jiang and Valentin Kline. Some questions that led me through the process of building the speaker and working with it were, what is the shadow of sound...
The directed speaker system that I constructed allows to isolate the viewer from fellow viewers - an act that creates a cut in the communal experience of a mutual destiny. After the viewer is exposed to the contents that are broadcasted by the directed broadcast I expect that the viewers will involve others in their experience. I expect that through sharing the experience with others, an alienation will arise based on the dissonance of the difference between viewer’s experiences.