Various mitigation systems have been utilized for addressing heavy-weight impacts within the built environment. There is no standardized measurement system for assessing heavy-weight impacts and no metric for describing the performance of a building assembly, material, or sound level for this type of impact. The authors have continued their investigation into measurement methods for hard and soft heavy-weight impacts on a variety of structures and fitness flooring materials. This paper presents recent results.

The measurement of low frequency impact sound in rooms (below 100 Hz) is critical to determining human response and acceptability of floor ceilings [1], [2]. Measurement uncertainties generally increase at lower frequencies, and a lack of precision is a general problem that ratings of low-frequency noise must overcome. Impact noise uncertainties at low frequencies are reviewed. The effect on measurement uncertainty of changes to the measurement procedure (such as fixed vs. roving microphones, measurement duration, microphone position, number of tapping machine locations, etc.) is studied, with emphasis on the uncertainties in the 50-80 Hz third-octave bands. The measurement uncertainty will be related to the precision desired to accurately relate to human reaction.

Impact noise insulation has traditionally been thought of mostly in terms of vertical adjacencies. However, impact noise is transmitted in all directions though a building, and lateral and diagonally adjacent impact noise transmission can be significant. Lateral and diagonal impact transmission is a one-junction structural flanking path and is, therefore, amenable to statistical energy analysis-based calculation methods such as ISO 12354. In this paper, we review the relevant results from structural flanking path calculations and show how this provides a framework for understanding major features of lateral impact noise transmission such as the frequency dependence and effect of structure type. In turn, measurement of lateral impact noise provides a method of estimating the vibration reduction across junctions. These findings are illustrated with examples from field testing.

The 2021 International Building Code (IBC) includes pressure-based metrics as the field acoustical standards for conformance. These include normalized noise isolation class (NNIC) and normalized impact sound rating (NISR) (ASTM E336-20 and ASTM E1007-21, ASTM International; 2021 International Building Code, Section 1206, International Code Council). Pressure-based metrics were intentionally used in lieu of power based metrics. The authors here address why pressure-based metrics are more appropriate than power-based metrics for field verification, following from previous work [LoVerde and Dong, “Field impact insulation testing: Inadequacy of existing normalization methods and proposal for new ratings analogous to those for airborne noise reduction,” JASA 118, 638 (2005); LoVerde, Dong, and Rawlings, “Sound pressure-based ratings for evaluation of in situ sound isolation,” Denver (2022)]. Furthermore, the authors shall present the application of these metrics as they pertain to Building Code requirements. This paper will include and present code interpretation as it relates to sample size and evaluation for compliance as it relates to Building Code and sampling of systems for acceptance.

Vehicular traffic noise for free-flowing roadways and highways generally follows statistically predictable flow rates and vehicular mix. The authors’ earlier work in this area examined long-term variations in traffic noise level with the purpose of establishing maximum hourly levels for vehicular sources (“Defining vehicular noise levels to manage risk associated with exterior façade design,” LoVerde, Dong, Rawlings, Internoise 2014 Melbourne) and general average sound level (“Noise prediction of vehicle sources on arterials using measured sound data,” LoVerde, Dong, Rawlings, ASA 2014 Providence; “Methods for estimating the variance in traffic noise distribution from short-duration measurements,” LoVerde, Dong, Rawlings, ICSV 2015 Florence). When the COVID-19 pandemic resulted in lockdowns, traffic patterns at the measurement location in Southern California were affected. The authors’ examination of traffic data revealed that the changes in traffic patterns did not affect noise level significantly, but variability in sound level across the 24-h period increased substantially (“Changes in statistical traffic noise descriptors during COVID-19,” LoVerde, Dong, Edwards, Rawlings, ASA 2021). For this paper, the authors have undertaken comparison of pre-, during-, and post-lockdown vehicular traffic noise levels over a several-month period for the purpose of understanding how measurement of traffic noise is implemented and interpreted.