Accurate Estimation of the Environmental Noise Through Sampling Approach: Selection of the Measurement Time

The influence of measurement time on the measure- ment uncertainty of environmental noise is explored when the sampling approach is performed as opposite to the continuous acquisition. An original procedure based on a bootstrap method was proposed to determine the measurement episode, which takes into account the statistical variability of the acquired sound pressure levels and may be effectively applied to different noise sources. This paper focuses on the robustness analysis of the algorithm proposed for determining the measurement time interval. This is expected to be independent of the instrumen- tation employed and suitable for estimating the influence of the measurand variability on the measurement uncertainty. The experimental verification is reported against the real data from road traffic noise acquired through different class 1 sound level meters. Results show the proposed sampling strategy is suitable for the selection of the significant measurement episodes upon which to predict the short-term noise indicator representative of the acoustic phenomenon. The proposed approach resolves the ambiguity of the standard ISO 1996-2, by introducing a quantitative criterion based on the measurement uncertainty of the equivalent sound pressure level, which may be adopted by the practitioner for selecting the measurement time.