An experimental evaluation of the impact of scattering on sound field diffusivity

This work provides a systematic experimental evaluation of the impact of scattering on sound field diffusivity in a proportionate medium-small sized room. A scale model is set up in many ways by increasing the amount of scattering, and detailing measurements of the reverberation time in each case. With the aid of statistical tools, the role of scattering in the process of achieving a diffuse sound field from initially non-diffuse conditions is outlined and a set of reference scattering threshold values is derived. It is found that the same values ensure the validity of the Sabine formula when corrections are adopted in its application. Reverberation time is also predicted in non-diffuse conditions by the Nilsson approach, and its performance is systematically compared with measurements. The Nilsson method was a better predictor of reverberation time under non-diffuse conditions than classical reverberation time formulas. However, for diffuse sound fields, the same method tended to diverge from measured values. An application using more realistic room conditions is developed together with computer simulations. The results outline that there is limited benefit to using computer-aided design models instead of simple formulas to predict reverberation time for non-diffuse sound fields in proportionate medium-small sized rooms.