An experimental study for multilayered building elements with a sub-study on the effect of finite-size test specimens

Sound transmission through multilayered building elements was investigated in this experimental study in which sound transmission losses were measured in 28 wall samples with various layer configurations including gypsum board, steel plates, vinyl damping material, glasswool, and airgap. ASTM E90-90 standard was used in the experiment that was conducted at the Riverbank Acoustical Laboratories within a study supported by a grant from IIT/IITRI. The effects of some physical parameters were investigated and comparisons were made in terms of frequency-dependent TL, Rw, and STC values. Test specimens of two sizes (10 m2 and 2.9 m2), were used to derive a size-effect correction which could be used in comparison of measured data and those to be calculated for infinite elements. It was found that the sound insulation values for small-size elements were higher at low frequencies than those of large-size elements, whereas they were lower at mid and high frequencies for both single- and multilayered elements. Statistical analysis indicated that the difference was significant and more emphasized for double gypsum walls with airgaps. Based on the experimental data, variations of transmission loss nd insulation values according to gap width and layer configuration are presented in comparative charts and the results are discussed.