Carvalho A.

This paper presents the analyses and results of an interlaboratory comparison test concerning impact sound insulation (L’n,w using the EN ISO 140-7 and 717-2). The main goal was to determine the reproducibility for the weighted normalized impact sound pressure level (for a concrete slab floor) and for all the involved parameters (reverberation time, impact sound pressure level and impact normalized sound pressure level, at the receiving room and for each 1/3 octave band from 100 to 3150 Hz). The testing results of individual participating laboratories were subject to statistical processing (calculation of the standard deviation and the standardized Z score). The interlaboratory comparative testing was done by single- or two-person measurement teams from fourteen Portuguese certified laboratories. Each measurement team used their equipment and their usual measuring procedure. No additional technical rules or suggestions were given to the measurement teams. The calculated reproducibility of the parameter L’n,w was calculated to be 2.3 dB with the fourteen individual laboratories Z scores varying from 0 to 1.8. The individual laboratories Z scores for the concerned reverberation time values were from 0 to 2.4 (with a range of values of 4 s for the RT results at the frequency bands of 100 and 125 Hz). The reproducibility for these RT values was calculated to be from 0.1 s in the higher frequency bands to about 3 s in the very low frequency bands. The laboratories’ Z scores for the normalized sound pressure level (L’n) were from 0 to 2.6 (with a range of values of 8 to 12 dB in the frequency bands of 100 to 160 Hz). The reproducibility for these values was calculated to be from 1.8 to 6.3 dB. All the measurement process is analyzed and the main conclusions are commented with indications how to perform to decrease the uncertainty.