IN SITU: Sonic Greenhouse is a large-scale audio-architectural installation that took place in September and October 2016 at the historic Winter Garden Greenhouse in Helsinki, Finland, and was experienced by approximately six thousand visitors. The piece transformed the entire glass structure of the greenhouse into a multichannel sound object or a macro-scale musical instrument.
Seventy structure-borne sound drivers — or vibration speakers — were used to transfer audio vibrations into the building’s glass panels, transforming them into loudspeakers. The idea was to drive sound all over the greenhouse's structure, creating an immersive ‘sound-dome’ in which unique aural impressions could be designed via custom spatialisation software.
The work brings together an original combination of sound and architecture with the larger issues related to the theme of ‘greenhouse’, such as environmental issues and the poetics of connection/separation inherent to a glass structure. The greenhouse metaphor was developed out of the compositional and spatialisation strategies involved in the piece, as well as in the establishment of a weather data feed into the installation’s generative sound engine.
The Helsinki Winter Garden comprises three different spaces: a) the central Palm Room (surface 280 square meters), b) the eastern wing’s Cactus Room (200 square meters) and c) the western wing’s social space (170 square meters).
In the Palm Room (a), acoustics are very reverberant and cathedral-like, and the space is filled with luxuriant vegetation. The sound work was designed to respond to this grandeur with full-spectrum and dynamic sonic constructions involving precisely rendered movements of sound within the glass structure. The Cactus Room (b) is very silent and intimate. In accordance, the sound was designed to occupy the space with precise, intricate sounds which draw the visitor’s attention to details and silent contemplation. The social space (c) was left as a relaxation space, convenient for discussion and studying printed documentation about the work.
Sonic Greenhouse was designed in intimate connection to the given space in order to foster integration into its physical structures, plant and human life, acoustics, and spatial poetics. An initial period of sensorial research was completed during multiple site visits in a period spanning over a year. This research observed how the staff and visitors behave in the space and how the building reacts to different weather conditions. These observations had a decisive effect on the design of the piece, which had to take into account high humidity levels, leakages, and regular activities such as watering the plants. The visits also served to familiarise ourselves with the acoustic specificities of the site.
The work stems from both artistic and technological research, aiming for fertile dialogue between the two. The technical research involved testing a large-scale structure-borne sound diffusion system directly on the structure of a building. We had no precedent knowledge of how such a system would sound and how it could be used to produce effective spatial aural impressions. On the artistic side, our research questions related to finding the optimal compositional strategies for a site-specific work in a large space with defined architecture, luxuriant plant life, social behaviour and interaction, abounding with multisensory stimuli.
Sonic Greenhouse implemented a sound diffusion system in two of the Winter Garden’s three rooms. A 50-channel system was built in the Palm Room and another, independent system with 20 channels was built in the Cactus Room. Two different types of audio transducers were used: structure-borne sound drivers attached on both the building’s glass walls and custom-made suspended plexiglass panels, and small cone loudspeakers enclosed in glass jars placed on the ground amidst the vegetation. Sound diffusion via structure-borne sound drivers was an aesthetic starting point for the entire piece. These drivers are able to transform a rigid surface into a full-range speaker with minimum visual impact. This combination of drivers and glass panel is acoustically ideal for creating large-scale soundscape-oriented aural impressions. The panels act as flat panel dipole speakers, providing a larger and more diffuse acoustic image than a more directive cone speaker. In this sense, diffuse sound emanating from glass panels creates an aesthetic unity: the sound source is not easily located and it perceptually blends into the glass, its transparency, and the surrounding landscape. The cone loudspeakers were designed to provide a spatial counterpoint to the wall and ceiling transducers, as well as to create a symbolic visual element: a speaker enclosed in glass replicates the greenhouse in miniature scale. In a sense, the speaker place in jars work as a metaphor for the whole installation.
After the sensorial exploration of Talvipuutarha, the initial sonic vision involved gamelan-type sounds and non-tempered scales. Intuitively, we felt that the glass and metal structure would resonate and shimmer with inharmonic, broad-spectrum, and complex sounds.
Based on this intuition, a large amount of initial sound material was then recorded with the percussionist Petteri Kippo at the studios of University of the Arts’ Sibelius Academy. The Sibelius Academy’s percussion collection was used, concentrating on metal, glass, and ceramic instruments. A total of three hours' of sound material was recorded. The above photos depict Petteri Kippo in the recording studio. Close mic’ing techniques were used in order to ‘zoom’ into the sound and retrieve as much detail as possible. The Talvipuutarha greenhouse acoustics are very reverberant and may cause a loss of detail in sound. It was thus very important for us to have high precision sound material to start with.
The resulting sound bank served as a basis for the composition, each composer employing his own set of techniques and software. A difference in approach was noted here: O. Lähdeoja used multitrack techniques to formulate a tape-music inspired approach to sound composition and spatialisation, whereas J. Moreno used spatial engines in order to move sound events within the space.
The final diffusion engine was made with two computers running max/MSP — one for each room with sound (Talvipuutarha’s third room was left without sound in order to preserve a social space for the visitors). In the Palm Room, the engine was programmed to create a generative mix between Lähdeoja’s and Moreno’s compositional materials, interweaving both composers into a continuous, ever-changing texture. In the Cactus Room, the approach was entirely generative, based on granular synthesis and partly controlled by external weather data.
Sonic Greenhouse was a collaborative work by two composers of electronic music, Otso Lähdeoja and Josué Moreno. The process was completed in parallel and in dialogue, with no specific personal tasks assigned. The resulting audio-architectural installation should therefore be considered a duet. Daniel Malpica joined as a graphic designer, creating a distinct visual character for the piece’s communicated look. For the present research catalogue, we decided to expand the initial graphic design into the RC’s rich-media environment, in line with the piece’s initial graphic look.
- Building as instrument:
David Byrne, Playing the Building
<http://journal.davidbyrne.com/explore/playing-the-building>.
Nicolas Maigret and Nicolas Montgermont, The Resonant Architecture Project <http://resonantarchitecture.com>.
- Sonic Weather:
Rodolphe Alexis, Mille et une Orchidées
<http://www.mnhn.fr/fr/visitez/agenda/expositions/mille-orchidees>.
Janet Cardiff, The Forty Part Motet (2001)
<http://www.cardiffmiller.com/artworks/inst/motet.html>.
- Glass and Sound:
Baudon Oosterlynck's listening instruments
<http://www.art-in-society.de/AS11/BO/B.O.in.Stavelot.html>.
- Spatial Sound Sculptures:
Christina Kubisch