Performances of low frequency impact sound in wooden buildings

Since 1999 Sweden has required an extended frequency range for sound insulation in residential buildings, using 50 Hz as the lower limit. This regulation update has driven the design and development of multi storey residential building systems with wooden structures in a positive direction. Already in the mid 1980'ies there existed scientific proof that it the perceived impact sound will improve if the frequency range was extended below the lower standard limit 100 Hz at that time. Lately, researchers have indicated that the perceived impact sound can be even further improved if the frequency range is extended below current lower standardized limit of 50 Hz. Assume that the frequency range for impact sound requirement will be further extended to include frequencies from 25 Hz, what would that mean for modern wooden apartment buildings? Acouwood and Kuster & Partner AG are collecting data from 20 Hz, no matter if the standard measurement procedure cannot be applied below 50 Hz. It gives a good overview of potential annoyance risk but also of acoustic performances of modern sustainable multifamily buildings and how they can be improved. This paper summarizes measurement results of impact sound from 20 Hz in several wooden buildings.