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T V Í S Ö N G U R
Acoustic Modelling  March 2017

Background                                                                                   Icelandic TV report featuring this work (at 0:45)

Opened to the public in 2012 and situated in the mountains above Seydisfjordur, north east Iceland, Tvísöngur is a sound sculpture designed by German artist Lukas Kuhne. Constructed entirely of smooth unpainted concrete at 100mm thick throughout, it consists of five interconnected domes - nicknamed "Fa", "La", "Si", "Do" and "Mi" in order of decreasing size. Each dome’s distinct size produces an individual resonant frequency corresponding to a tone in traditional Icelandic five-part harmony.

 

Rounded archway openings built into the walls of each dome allow visitors to enter the structure and experience the unique acoustical characteristics of the space. These arched openings also act as Helmholtz resonators, as wind blowing in off the cliffs rushes into and across the openings, the air within the structure resonates. Nicknamed the ‘singing concrete’, Tvísöngur was designed for several voices in order to preserve Iceland’s musical heritage, which was one of the first and now only surviving forms of improvised polyphonic chants in Europe.

 

In collaboration with the artist Lukas Kühne, using ODEON acoustic simulation software, an acoustic model replica of the structure was built in order to visualise how sound propagates through the structure, investigate how certain frequencies are resonated by each individual dome, and produce simulated impulse responses to create auralizations.

Source / Receiver Positioning

One source and one receiver was positioned at the central vertex of each of the five domes at 1.5m in height. Those within the structure would most likely experience the acoustic conditions from a standing position as there is no seating, therefore a source/receiver height of 1.5m was most suitable. The only exception being dome 'Mi' which, due to its lower ceiling height, was lowered to 1.2m in order to be a satisfactory distance from wall boundaries in accordance with guidelines set out by ISO 3382. For each source, a receiver position was located in each of the remaining 4 domes. A total of 20 impulse responses were therefore rendered (5 sources x 4 receivers). The HRTF's used for binaural impulse response rendering were from the ODEON database, Subject_021Res10deg (Algazi, 2001). Please see images below for more detailed source/receiver positioning.

Auralisations

Audio Example 1 - Flamenco Guitar

Source Position 2 (Dome La), Receiver Position 4 (Dome Do)

Anechoic recording "Flamenco 1" from TH Köln, Laboratory for Acoustics, Audio Technology

and Audio Signal Processing. Creative Commons Licence, Available to download here.

Audio Example 2 - Cello

Source Position 1 (Dome Fa), Receiver Position 4 (Dome Do)

Anechoic recording "Cello" from Illinois Institute of Technology by Ralph T. Muehleisen, 

licenced under a Creative Commons - Non Commercial 2.5. Available to download here.

Audio Example 3 - Female Soloist, Guitar and Choir

Source Position 3 (Dome Si), Receiver Position 1 (Dome Fa)

Anechoic recording "Iphigenia" from the ERATO Project, Il Gruppo di Ricerca in Acustica 

(The Acoustic Research Group) University of Ferrara. Available to download here.

Sound Propagation Visualisations

Billiard ball sound propagation animations demonstrating the behaviour of sound travel within the structure. Animations created using Odeon Acoustic Simulation Software. Source Position 1 (Dome Fa) displayed at the top of this page.

Source Position 2 (Dome La)

Source Position 3 (Dome Si)

Source Position 4 (Dome Do)

Source Position 5 (Dome Mi)

Information

With thanks to the artist Lukas Kuhne for providing the detailed plans to make this project possible. For more detailed numerical data, please see The Open Air Library, where you can upload your own anechoic recordings and hear them auralised in Tvísöngur.

Flamenco Guitar - Tvisongur Auralisation
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Flamenco Guitar - Anechoic Recording
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Female Soloist, Guitar and Choir - Anechoic Recording
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Female Soloist, Guitar and Choir - Tvisongur Auralisation
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Cello - Anechoic Recording
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Cello - Tvisongur Auralisation
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Sketchup Model
"Tvisongur" by Navin Rajagopalan (Flickr) Available here