Evaluation of field impact sound pressure levels as a function of tapping machine location

Abstract

Field impact sound insulation in the United States is typically quantified in terms of field impact insulation class, which is defined in ASTM E1007. This standard requires averaging the receiving room impact sound pressure levels (ISPL) generated by the tapping machine in four defined positions. In a previous paper [LoVerde and Dong, J. Acoust. Soc. Am. 121, 3113 (2007)] the authors analyzed several hundred field tests to determine effects of reducing the number of tapping machine positions on the FIIC rating. In this paper the analysis is extended to look at the detailed effects on the third-octave band ISPL, which may impact design decisions more than the overall FIIC rating. The effect of reducing the number of positions as a function of assembly construction is also examined.

Measurement of low frequency impact insulation

“…Direct comparison is not possible since a different set of tapping machine positions was used, but the concrete assembly, despite lacking a joist structure, has a similar range of variation as the wood joist floor. In our previous study [9], we also observed no systematic difference between wood joist and concrete floors. This implies that the variation is not attributable to the tapping machine being on or between the joists.…”

“…Using the ASTM standard tapping machine positions, two of the positions are directly above a joist and two are between the joists. The previous studies [9], [10] did not identify any systematic differences between the tapping machine positions. However, those studies did not examine the bands below 100 Hz, while Larsson et al observed this effect only below 100 Hz.…”

“…The authors have presented two studies [9], [10] on the effect of tapping machine position. These studies focused on the effects of number of tapping machine positions that are averaged.…”