Assessing the low-frequency measurement procedure for the measurement of impact sound insulation using the rubber ball

ISO 16283-2 includes a procedure for measuring field impact sound insulation at low frequencies using a tapping machine to improve the repeatability, reproducibility, and relevance of results in the 50, 63, and 80 Hz one-third octave bands in small receiving rooms (volumes less than 25 m3). However, the low-frequency measurement procedure with excitation from a standardized rubber ball was not included because the link between measurements of Li,Fmax from the central region and corners had not been established at the time of writing. This paper assesses the use of the low-frequency measurement procedure with a rubber ball source through measurements of Li,Fmax in a vertical transmission suite at the Building Research Institute (Japan). It also provides analysis of the modal sound field in the receiving room due to rubber ball excitation of the concrete slab. The results indicated that the low-frequency measurement procedure was beneficial in this 60 m3 room to estimate the room average sound pressure level below 80 Hz. Future work could therefore evaluate the low-frequency procedure in the field with different room volumes and floor constructions.