Sammendrag
Low frequency sound and floor vibrations from impacts on timber floor constructions have been studied for almost ten years at the Norwegian Building Research Institute (NBI). A major part of our results are from field measurements, but this presentation will focus on results from two different experiment set up at the laboratory. These investigations include studies of different excitation methods with measurements in the frequency range above 20 Hz. The measurement objects varies from common, simple timber floor constructions to constructions with stiffeners or added mass at the top floor. Results are given for impact sound insulation measurements with both the ISO tapping machine and the Japanese testing method with a rubber ball. Measured improvements with increased mass or stiffness are also compared with calculated improvements in the frequency range below 200 Hz.