Laboratory Acoustical Testing of Wall System containing Expanded Polystyrene Foam
Test Objectives:
Measurement of airborne Sound Reduction Indices ( R ) of sample wall system in accordance with AS1191-2002 Acoustics – Method for Laboratory Measurement of Airborne Sound Transmission Loss of Building Elements.
Determination of Weighted Sound Reduction Indices ( R w ) and Spectrum Adaption Terms (C tr) in accordance with AS/NZS ISO 717.1.2004: Acoustics – Rating of sound insulation in buildings and of building elements – Airborne sound insulation.
Description of Test Specimens
| Side 1: | 6mm concrete render applied to 60mm thick expanded polystyrene foam. The polystyrene applied with sheet lengths vertical. Framing: 90mm timber studs at 450mm centres |
| Side 2: | 10mm Plasterboard applied with sheet lengths vertical. Joints no set, some visible gaps up to 8mm wide. Edges caulked with expanding polyurethane foam. |
Description of Test Facilities:
The tests were carried out in a purpose-designed transmission loss suite, comprising two adjoining reverberant rooms, designed in accordance with AS1191-1985.
Room construction:
solid concrete; independent construction for source and receiving rooms with separate foundations.
Room shape:
Rectangular parallel piped for both rooms; aspect ratios 1.6:1.3:1 for both rooms.
Room Volume:
Source room 100m3; receiving room 170m3 Average Absorption coefficient: less than 0.06 at all frequencies.
Diffusers:
Receiving room diffuser area 30.7m2 compared with largest surface (floor/ceiling) of 40m2;ratio 0.75.
Test Aperture:
3.16m x 3.16m (Nom). In this instance, craft wood jamb linings were fitted to the test aperture. These reduced the effective aperture area to 9.98m2.
Instrumentation
- Precision sound level meter, Rion NA-27 (S/N 00380650).
- Acoustical calibrator, Bruel & Kjaer type 4231 S/N 1897734.
- Sound source, custom made pink noise generator, 150W power amplifier and a stereo two-way loudspeaker system.
Test Procedures: Sound Source and Location
Broad band pink noise located in the rear trihedral corners of the source room.
Space and time average:
- Continuous moving path
- Repeated three times
- Path length approx 15m
- Averaging time 120 sec.
Equivalent Absorption:
Was determined by reverberation time measurement using the built-in software with the Rion NA-27 sound level meter. The sound source was used to excite the room. Two source locations were used each with tree microphone locations to comply with the Code.
Measurements Precision:
Each measurement was repeated three times. Repeatability was better than 1dB in every frequency band.
Test Results:
The test results are appended with a summary provided in Table 1 and complete 1/3 Octave data provided in Table 2.
Weighted Sound Reduction Index (rw)
6mm Render, 60mm ESP on 90mm timber studs at 450mm centres, with 10mm plasterboard (Plasterboard joints no set, edges caulked with expandable polyurethane foam)
