The challenge
The main difficulty concerned the large student hall, which with 730 places had to be sufficiently sized with constraints of natural lighting met by large glazed sections in the outside walls and roof, while having a high ceiling to avoid a “closed in” feeling in such a large hall. All these parameters act against acoustic comfort.
This project was subject to French acoustic regulations dated 25 April 2003 concerning noise reduction in school buildings. The restaurant rooms and hall would need to comply with the following reverberation times (RT):
For restaurant rooms of less than 250 cu. m: 0.4 sec. ≤ RT ≤ 0.8 sec.
For restaurant rooms of more than 250 cu. m: RT ≤ 1.2 sec.
The solutions
In order to meet the acoustic requirements within the architectural constraints, the following four objectives were agreed:
- To divide the hall up into areas
- To select sound dampening materials
- To develop appropriate ceiling shapes and textures
- To reorganise spatial volums
With regard to the reorganisation of the spatial volumes
To ensure good acoustic comfort in the restaurant hall, we had to reduce the impact of the parallel glass surfaces (which were necessary to gain natural light in compliance with HEQ specifications), provide sound dampening as close as possible to the students and create much more private areas through spatial reorganisation. We therefore decided to install Texaa acoustic screens.
The technical design proposal was to implement Texaa rigid screens with melamine foam cores, which would significantly absorb sound in the frequency range of human speech. The screens have the added advantage of dampening sound on both sides, while contributing colour from a very wide palette of possibilities as well as volume. By arranging gaps between them, visibility would not be hampered.
Conclusion
When our acoustic screens were installed, measurements were carried out in the fully furnished restaurant rooms with source sounds in several locations in order to characterise the internal acoustics of the finished volumes. The reverberation times around 0.6 secs. all complied with the regulatory requirements.
