Auditory evaluation of sound signals radiated by a vibrating surface

This paper presents a combination of vibroacoustic and psychoacoustic studi es of sounds radiated by a vibrating structure. The calculated sound field is the sound pressure radiated by a baffled thin-plate structure immersed i n a fluid, on the surface of which the acceleration is given. Various confi gurations are selected for the time and space functions of the acceleration variable, each configuration leading to a particular acoustic signal (a lo w-frequency tone complex in our case). These signals are then transformed i nto sound files, which are used as test signals in psychoacoustic experimen ts for assessing their perceptual attributes and quality. Two experiments w ere run. In the first one, the unpleasantness of a series of signals at dif ferent levels was measured by direct estimation and compared with their cal culated loudness and sharpness using Zwicker's model. The same measurements were repeated with the signals set to the same maximum amplitude. In the s econd experiment, the pleasantness of another series of sounds at equal lou dness was measured, as well as dissimilarity and preference on pairs of the se sounds. An MDS analysis was run to extract auditory attributes that coul d account for the perceived differences between sounds and correlate with t he estimated pleasantness. The results from the first experiment show that pleasantness is always highly (and negatively) correlated with loudness. Th e same holds for sharpness, when sounds are played at the same maximum ampl itude. The second experiment shows that the perceptual attributes revealed by the MDS analysis are related to pitch and timbre, the latter being highl y correlated with pleasantness. Overall, this study confirms the interest o f extending vibroacoustic studies to a more complete "psychomechanical" inv estigation of the whole process of sound generation. It is suggested that s uch investigations may apply to product sound quality and to active or pass ive noise control, by providing psychoacoustic feedback to the design of th e vibrating structures or of the noise-control systems. (C) 2001 Academic P ress.