In field measurements UNI EN ISO 140 application for large volume openspace rooms

The methodology for measurements in large room is not covered explicitly by the ISO 140 standards. From some hints in the ISO 140-14 standard it was possible to identify, through the distribution of sound levels analysis within the open-space, smaller spaces (“virtual volumes”) to be used as a minimum unit to survey measurement. The measures focused on the airborne sound insulation between different units (R'w) and on the floors impact sound insulation (L'nw and L'nTw). The “virtual volumes” (and their sizes) must also be considered to calculating acoustic indices. However, ISO 140-14 does not specify the appropriate treatment to characterizing each room with a single index. In this study index was obtained both from the logarithmic average of “virtual volumes” values, both from the analysis of the extended measures over the entire volume and surface area of the floor. The processed and compared data allowed to define some considerations concerning the most appropriate methodology to performing the measurements and evaluating index in these types of spaces. The criterion elaborated from UNI EN ISO 140-14 hints is necessary to carry out measurements in large rooms. Index R'w is suitable for comparison between virtual volumes with different surface area and volumes but same height. For the same reason, logarithmic average and analysis of extended measures are both suitable to evaluating R'w. L'nw is strongly affected by geometrical variables (volume): it isn't appropriate for the comparison between virtual volumes characterized by different volumes.