Sound absorption and sound transmission loss of perforated corrugated board

Sound absorption capability and sound transmission loss of non-perforated and perforated triple A tri-wall corrugated board were estimated by a sound transfer function method. It was found that the cavity which had been formed by perforation behaved as a Helmholtz resonator, single frequency resonator. Mean sound absorption coefficients of non-perforated, and 1.01%, 1.77%, 3.78% and 7.48% of surface area perforated, corrugated board specimens were 0.36, 0.41, 0.41, 0.41 and 0.40, respectively. Especially, in case of 7.48% perforation area of three liner boards (surface and two inner liner boards) perforated all together, sound absorption value reached 100% in the frequency of 1.4 kHz. Mean of sound transmission loss of non-perforated, surface liner layer perforated, and three liner layers perforated board were 17,08 dB, 11.84 dB and 7.55 dB, respectively. The sound transmission loss of the perforated boards were lower than that of non-perforated one. The NRC (noise reduction coefficient) of the perforated corrugated board was about 0.35, which was higher than the NRC (0.3) of 1.1 cm thick commercial gypsum board, and therefore, this board could be used as a sound absorbing board.