Acoustic Modelling : Tvísöngur

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.












Information

With thanks to the architect 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
00:00 / 00:00
Flamenco Guitar - Anechoic Recording
00:00 / 00:00
Female Soloist, Guitar and Choir - Anechoic Recording
00:00 / 00:00
Female Soloist, Guitar and Choir - Tvisongur Auralisation
00:00 / 00:00
Cello - Anechoic Recording
00:00 / 00:00
Cello - Tvisongur Auralisation
00:00 / 00:00
Sketchup Model