1960 年 16 巻 4 号 p. 265-273
Transmission loss of single Partitions were measured in reverberant sound field for common building materials, for example plywood, glass, concrete block, etc. In arranging the transmission loss curves, mf, that means (mass per unit area)×(frequency), was taken as abscissa instead of f. Such an arrangement has clarified the relation between the measured transmission loss and the mass law. That is common to those homogeneous materials and consists of three regions as to mf. When mf<10^4kg/m^2・c/s, measured transmission loss is larger than the mass law by several decibels. 10^4<mf<10^5, transmission loss decreases on account of "coincidence effect". 10^5<mf, transmission loss curves recover from their minima, and agree with the mass law. As regards the coincidence effect, for the homogeneous materials, the agreement was found between the frequency at which the minimum of transmission loss occurs and Cremer's critical frequency f_c. In our study f_c was calculated by the static Young's modulus of material. Several kinds of sandwich structure panels have been treated in the same way as above-mentioned. The result of our study shows that the transmission loss of single partitions, either homogeneous or inhomogeneous plates, is roughly predicted by the mass law. In detail, however, the transmission loss characteristics are different depending on the kind of structures. The difference in dynamical property between structures can be pointed as one of the causes of them.