Auditory perception of geometry-invariant material properties

Accurately modeling the intrinsic material-dependent damping property for interactive sound rendering is a challenging problem. The Rayleigh damping model is commonly regarded as an adequate engineering model for interactive sound synthesis in virtual environment applications, but this assumption has never been rigorously analyzed. In this paper, we conduct a formal evaluation of this model. Our goal is to determine if auditory perception of material under Rayleigh damping assumption is 'geometry-invariant', i.e. if this approximation model is transferable across different shapes and sizes. First, audio recordings of same-material objects in various shapes and sizes are analyzed to determine if they can be approximated by the Rayleigh damping model with a single set of parameters. Next, we design and conduct a series of psychoacoustic experiments, in subjects evaluate if audio clips synthesized using the Rayleigh damping model are from the same material, when we alter the material, shape, and size parameters. Through both quantitative and qualitative evaluation, we show that the acoustic properties of the Rayleigh damping model for a single material is generally preserved across different geometries of objects consisting of homogeneous materials and is therefore a suitable, geometry-invariant sound model. Our study results also show that consistent with prior crossmodal expectations, visual perception of geometry can affect the auditory perception of materials. These findings facilitate the wide adoption of Rayleigh damping for interactive auditory systems and enable reuse of material parameters under this approximation model across different shapes and sizes, without laborious per-object parameter tuning.