Sound insulation measurements on a series of double plasterboard panels with various infills

The Influence of the Wall Cavity on the Transmission Loss of Wall Systems — Experimental Trends

“…Novak also noted the difficulty encountered with measuring the airflow resistance of the cellulose material due to the movements in the material. Finally, polystyrene was ranked as the worst material for the low frequency range as Mulholland's [14] observed that it hardly made any contribution to the STL and even performed worse than the empty cavity situation for part of this frequency range as shown in Figures 2 and 3.…”

“…Consequently, Loney [13] concluded that the thickness rather than the density of the material is a more reliable general indicator of a material's effect on the STL. Furthermore, Mulholland's [14] investigation showed how unreliable the use of the material's density as the only indicator of the materials effectiveness on the STL can be. Mulholland's [14] results presented in Figure 1 and Figure 2 showed that the lightweight double leaf gypsum plasterboard wall system with denser mineral-wool as an infill, produced higher STL than polyurethane or polystyrene as an infill in the 50 and 100 mm cavity: However, the polyurethane infill produced higher STL than the polystyrene even though the densities of both materials were the same (i.e.…”

“…The results shown in Figure 4 are for a 1/4 inch (6.35 mm ) plywood double leaf wall system with two 2 inch (50.8 mm) wooden studs at 2 ft (609.6 mm) centres. Mulholland [14] commented on these results and speculated that it is possible that complete filling of the cavity will not only dampen the cavity resonances, such as the mass spring mass resonance and the various standing waves, but it will also add a degree of damping to the panel resonances and the coincidence effect. On the other hand Quirt [11] viewed the complete filling of the cavity as causing a lateral shift in the STL for the lower frequencies, with the mass air mass resonance frequency shifting to a lower frequency in this case; Kurra [21] also observed this lateral shift in the mass air mass frequency.…”

“…Mulholland's [14] investigation showed that sound absorption material added to the wall cavity of the lightweight wall construction improved the STL of the system, but had no effect when heavy panels were used. Uris et al's [23] investigation showed how the properties of the wall panels influenced the effect of the sound absorption material placed within the wall cavity.…”

“…In the low frequency range polyethylene, glass-fibre and polyurethane are all ranked as performing equally well. Although Mulholland's [14] results showed that both mineralwool and polyurethane foam performed equally well and significantly better than polystyrene; Warnock's [12] and Quirt's [11] work showed that mineral-fibre didn't perform as well as glass-fibre and polyethylene in the low frequency range. Novak's [10] results showed that the higher density mineral-wool performed equally well when compared to the lower density mineral wool, glass-fibre and polyethylene/dacron; while Royar [8] observed that the STL with mineral-wool infill didn't improve much when the density was varied from 18 to 125 kg/m 3 Novak's [10] and Royar's [8] results with mineral-wool infills were different from Uris et al's [15] which showed that the low density mineral-fibre performed better than the high density material in the low frequency range.…”