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Effect of floor coverings on impact sound insulation can be described with a vibration level reduction (Δ La). In this study, tests with two floor coverings, eight wooden slabs and with a concrete mock-up slab were conducted by applying the method presented by Sommerfeld and the standard ISO 16251-1. The aim was to study the differences affecting the measured Δ La and the behaviour of the floor coverings installed on different slabs. The results suggest that the Δ La on concrete slabs do not correspond with the Δ La on wooden slabs. Thus, the floor coverings should be measured on wooden slabs when they are to be used within the timber construction industry. The results also show that the coverings should be measured on the wooden slabs where the products are expected to be used. In addition, a standardized test method for the wooden slabs corresponding the method of ISO 16251-1 should be developed.

Background noise masks living sounds in apartment buildings. Depending on the sound insulation properties of the structures of the apartments, background noise affects the audibility of the perceived airborne and impact sounds from neighboring dwellings. This preliminary study focused on the masking effect of the background noise generated by HVAC systems on the impact sounds generated by walking on concrete floors. The study was carried out by determining the signal-to-noise ratios of walk induced sound levels on the concrete floors and measured background noise levels. The walking sounds were generated by walking with socks and shoes on nine concrete floors, and the sound pressure levels were measured in a receiving room below the floors. The background noise levels, where these walking sounds were compared, consisted of the results collected in 210 measurements carried out in Finnish apartment buildings. The results of the study show how it is likely that the background noise masks sound from walking with socks and shoes differently. To investigate the phenomenon more in detail, follow-up research has been proposed.