Originally Posted by Dennis Erskine
A couple of minor points: diffusors do not affect RT60 in the manner described nor will they have any impact on standing waves.
I have observed, and the literature strongly suggests, that RT60 is lowered with added diffusion, at least when the absorptions of different room surfaces vary.
M. R. Hodgson, Evidence of diffuse surface reflections in rooms, J. Acoust. Soc. Am. 89, 765-771 (1991).
M. Lam, A comparison of three diffuse reflection modeling methods used in room acoustics computer models, J. Acoust. Soc. Am. 100, 2181-2191 (1996).
M. Lam, The dependence of diffusion parameters in a room acoustics prediction model on auditorium sizes and shapes," J. Acoust. Soc. Am. 100, 2193-2203 (1996).
M. Hodgson and E. Nosal, "Experimental evaluation of radiosity for room sound-field prediction," J. Acoust. Soc. Am. 120, 808-819 (2006).