ODEON Room Acoustic Modelling of an Open Plan School Design

ODEON, the room acoustics modeling and auralisation PC software, can model the acoustics in rooms and spaces from their geometries and surface properties. Powerful yet easy to use, ODEON is equally at home in simple and complex applications and is used to verify the acoustics in enclosed spaces even before the first brick is laid or remodeling started.

Ørestad school is the first school to be built specifically to fulfill the intentions of the Danish school reform of 2005. The school was built to a totally new concept, with no traditional classrooms, but four 'study zones' instead, one on each of four floors linked by a broad, spiral staircase. As such, sound can reverberate not only around each floor, but also between them.

The school was designed on the basis of the designer’s conviction that architecture encourages movement, and those open, flexible spaces, which permit a greater degree of interaction, give a better environment for working and learning. The staircase is the central element, where movement will naturally occur and there will be a lot of commotion; but the further away from the centre you go, the greater the tranquility and the chance to settle down and work.

Shortly after Ørestad school was opened, a somewhat surprised architecture critic wrote that even with several hundred students in the building, the expected "noise inferno" did not exist, and in fact the acoustics were actually very comfortable.

Acoustic modeling – a challenge
Odeon has been used as the spatial-acoustic modeling tool by many consultants and universities all over the world since the early 1990s. The job of performing acoustic simulations for the Ørestad school project was on the limit of what was technically possible in 2004 in several different ways.

ODEON uses a combination of "ray tracing" and "radiosity", in which all ray reflection points generate secondary sources. The sound which is “visible” from the recipient point is then collected. Using this method, sound simulation could be extended to all parts of the building model to which sound radiation could extend. A typical simulation involved 20,000 rays, each of which has a reverberation time equivalent to 2 seconds, which could generate around 3 million secondary sources. Using the computers available in 2004, simulation time was around 20 seconds for ray tracing and 50 seconds for calculating impulse response and acoustic parameters at a receiver point.

Auralisation – modeling of the subjective acoustic environment
The modeling was supplemented by examples of auralisation, including speech within the more enclosed teaching areas and audibility of loud music transmitted from the fully-enclosed rooms out to the open common areas. Particular auralisation of the noise from many people talking and eating in the canteen was made. Due to the canteen location in the open area on the ground floor just under the stairs, noise can spread via the central stairway to all five floors.

Auralisation allows subject evaluationof the aural environment

The results and auralisations were presented to the architects, engineers and school representatives, causing them to decide to use more sound absorbent materials.
Examples from this case study can be seen and heard on the Odeon website.

Conclusion – spatial-acoustic modeling takes on a new meaning
The example of Ørestad school is innovative on several levels: not only has the concept of "open plan school" been given a new meaning, as this may be the first time an open school can actually work - including acoustically; but also in relation to acoustic modeling and simulation, this project has paved the way for more general use of the terms "spatial-acoustic modeling" which can now also encompass multiple rooms and entire buildings.

Within the last couple of years, there have been innumerable examples of auralisation using the Odeon spatial-acoustic modeling program for similarly complicated projects, such as schools, office buildings, museums and shopping centers.

Contributor :- Jens Holger Rindel, ODEON A/S