  Geometrical approaches for room acoustics simulation have the advantage of
requiring limited computational resources while still achieving a high
perceptual plausibility. A common approach is using the image source model for
direct and early reflections in connection with further simplified models such
as a feedback delay network for the diffuse reverberant tail. When recreating
real spaces as virtual acoustic environments using room acoustics simulation,
the perceptual relevance of individual parameters in the simulation is unclear.
Here we investigate the importance of underlying acoustical measurements and
technical evaluation methods to obtain high-quality room acoustics simulations
in agreement with dummy-head recordings of a real space. We focus on the role
of source directivity. The effect of including measured, modelled, and
omnidirectional source directivity in room acoustics simulations was assessed
in comparison to the measured reference. Technical evaluation strategies to
verify and improve the accuracy of various elements in the simulation
processing chain from source, the room properties, to the receiver are
presented. Perceptual results from an ABX listening experiment with random
speech tokens are shown and compared with technical measures for a ranking of
simulation approaches.
