Analysis and synthesis of the sounds of impact based on shape-invariant properties of materials

We present a model relating materials to the sounds they make when struck. The model exploits a shape-invariant property of materials: the angle of internal friction. We demonstrate the utility of this model in both analyzing and synthesizing sounds generated by impulsive excitation. For the analysis of impact sounds, we present an active approach for discriminating different materials by impulsively contacting (hitting) them, and sensing the interpreting the resulting sound. Experimental results suggest that shape-invariance may be encoded in the functional form of the relation between and angle of internal friction and frequency. For the recreation of impact sounds, we identify two key problems-the impact sound reconstruction problem, and the impact sound synthesis problem-and discuss preliminary considerations in developing solutions