HARDNESS RECOGNITION IN SYNTHETIC SOUNDS

Sound source recognition investigates recovery of different features of the objects, whose interaction lead to the generation of the acoustical signal. Among them material type have received particular attention, while recovering of material properties, such as hardness, have been scarcely considered. Hardness plays a significant role in the musical field too, especially for percussion instruments, where resonating objects of variable hardness are struck with mallets of variable hardness. Comparison of previous results on hardness recognition point toward the perceptual independence of the resonator and exciter properties. This issue was addressed in four experiments conducted on stimuli synthesized with a physical model, which allowed independent manipulation of the exciter and resonator properties. Free identification and forced choice tasks have been used to investigate the ability of listeners to discriminate variations in the exciter from variations in the resonator. Scaling tasks have been used to investigate the relationship between the synthesis parameters and the hardness estimates of the exciter and of the resonator. Free identification and forced choice data reveal a bias toward the interpretation of the acoustical signals in terms of features of the resonating object. Hardness scaling results reveal the perceptual dependence of exciter and resonator properties, although strong individual differences are found.