Manipulating Papua New Guinea Balsa by Design for Acoustic Absorption in the Built Environment

This study extends the knowledge of acoustic absorption properties of Papua New Guinea (PNG) balsa in three experimental stages for architectural applications in the built environment to improve the wellness of occupants. Stage one tested balsa as a stand-alone material in impedance tubes according to ISO 10534-2. The results indicated PNG balsa has low absorption properties across 100 to 5000 Hz in 1/3rd Octave-band centre frequencies. The largest arithmetic average of alpha (αSTAT) calculated was 0.20 from testing 25 mm thick end-grain balsa with a measured density of 87.5 kg/m3 (average of three discrete samples) and the lowest 0.05 from testing 50 mm thick perpendicular-grain balsa with a measured density of 112.5 kg/m3. Stage two tested balsa composite panels in a reverberation chamber according to AS ISO 354 and AS ISO 11654. The results highlighted the noise reduction coefficient and weighted sound absorption coefficient of two differently laminated composite panels was 0.75 and 0.80 αw and 0.75 and 0.75 αw respectively. Both composite panels had an identical perforated open area pattern and a type E-400 mount with an additional 100 mm insulation installed to the underside of the panel. The final stage, tested balsa composite panels in a commercial fit-out. The results presented an average reduction in reverberation time was 0.26 seconds, corresponding to an effective absorption coefficient of 0.47. This research concludes that well designed PNG balsa panels can provide a broad spectrum sound absorption, thus providing a comfortable acoustic environment for occupants.