Sound-Propagation Curves in Industrial Workrooms: Statistical Trends and Empirical Prediction Models

Predictions of workroom noise levels are based on predictions of the workroom sound-propagation curve, SP( r) – the variation with distance r from an omnidirectional point source of the sound-pressure level L_p( r) minus the source sound-power level L_wSP( r) = L_p( r)- L_w. While more accurate approaches such as ray tracing exist, from a practical point of view there is considerable scope for developing simple empirical prediction methods. In fact, several such models exist. However, these have short_comings which warrant the development of a new model. The approach taken here was to predict the slope(s) and absolute level(s) of the sound-propagation curve, approximated by one or more straight-line segments. With this in mind, octave-band sound-propagation measurements were made in a number of empty and fitted workrooms. The curves were approximated by one or two straight-line segments. The intercepts and slopes of the segments were then determined, and their averages and standard deviations calculated. The statistical trends provide information on the behaviour of sound in industrial workrooms. The results are used to develop simple empirical prediction models.