Experimental evaluation of simplified models for predicting noise levels in industrial workrooms

Simplified models for predicting noise levels in industrial workrooms have been developed by Friberg, Thompson et al., Wilson, Embleton and Russell, Kuttruff (“diffuse” and “specular” models applicable to fitted rooms only), Zetterling, Sergeyev et al. (applicable only to untreated workrooms), and Hodgson. They predict octave-band or A-weighted steady-state sound-pressure level as a function of source/receiver distance. These models have been programmed and evaluated by comparing predicted sound-propagation curves with those measured in 30 empty and fitted industrial workrooms with and without absorptive ceiling treatments. In empty workrooms the Sergeyev et al., Thompson, and Hodgson models worked quite well. The Zetterling model performed moderately well. The other models were inaccurate. Models underestimated levels in most cases. With the addition of absorbent treatments the accuracy of the Friberg, Wilson, Zetterling, and Embleton and Russell models improved; that of the Thompson and Hodgson models worsened. In fitted workrooms the Hodgson and Kuttruff (diffuse) models were accurate. The Friberg and Zetterling models were moderately accurate. The other models were inaccurate. The Thompson and Kuttruff (specular) models generally overestimated levels; the other models tended to underestimate levels. With absorbent treatment the accuracy of the Embleton and Russell model improved.