Modelling of sound fields in enclosed spaces with absorbent room surfaces Part III. Barriers

In the third paper on the modelling of sound fields in enclosed spaces with absorbent room surfaces, both Sabine and Millington absorption coefficients have been used for an acoustic barrier to investigate which approach produces the most accurate insertion loss predictions in a factory. The accuracy of three computer models in predicting the sound field on both sides of the barrier, using the two types of absorption coefficients is presented. In addition, a refinement of the diffraction approximation used in one of the models is described and validated. The results lend support, as do the previous results of this investigation, to the premise that Millington based absorption coefficients for absorbent material give consistently more accurate predictions than the standard absorption coefficients, when used in geometric computer models for the modelling of sound.