For sound absorption and sound transmission loss measurements, the existing international standards concern primarily building acoustics. The required measuring facilities are therefore very large and the corresponding surface areas of the samples are hardly comparable with the size of parts used in automobiles.
Such measurements are, however, of great importance for development, comparison and optimization of sound proofing materials. Consequently, although a very large number of small size devices have been proposed which are ingenious and useful when taken separately, each one gives results which are different from the others.
In this paper two devices will be presented. A small size reverberation room, which is a dimensional scale reduction 1:3 of a standardized room, is used for absorption measurements. A small emission room coupled with this small size reverberation room allows transmission loss measurements to be made. The surface area of the normal samples is 1.2 m2 for both devices and the results are comparable to those obtained according to the ISO Standards.
With regard to the efforts being made to standardize methods which are well adapted to automobile acoustics, it is suggested that these two devices could be taken into consideration.