Auditory evaluation of sounds radiated from a vibrating plate inside a damped cavity: Adjustment of the frequency resolution of vibro-acoustical computing

摘要

The issue of adjusting vibro-acoustical computational cost is especially important when enhancing the sound quality of a mechanical structure using simulation. Simulation parameters must be specified so as to: i) reduce computational cost, and ii) satisfy perceptual constraints. For a simple plate-cavity system, the adjustment of computational cost is investigated in the framework of evaluating the influence of variable structural parameters (cavity absorption, thickness and tightening conditions of the plate) on the auditory perception of sounds radiated inside the cavity. By concentrating on such a simple system, we eventually aim at achieving some recommendations adaptable to different vibrating structures of our environment - in the areas of transport and building - made up of plane elements coupled with enclosures. Considering stationary sounds, this study deals with the adjustment of a major frequency computation parameter, i.e. frequency resolution. The specification of the frequency resolution for vibro-acoustical simulations has a great influence on the spectral envelope of the sounds synthesized afterwards. Here, we modify the spectral envelope of real sounds in order to reproduce the envelope of spectra of synthesized sounds that would be computed in a simulation using a given frequency resolution. The adjustment process pursues the following objective: determining a frequency resolution for which certain perceptual outcomes relative to modified real sounds remain similar to those concerning the original real sounds. These perceptual constraints are pertinent regarding the issue of adjusting vibro-acoustical computational cost. These constraints notably concern the merits of the stimuli and are translated into two adjustment criteria. The results of a first experiment, an auditory evaluation of partial corpora of modified stimuli, highlight that, for the plate-cavity system under consideration, 4 Hz may be an adjusted frequency resolution. The consequences of using this frequency resolution are then further assessed through a second experiment, an auditory evaluation of the complete corpus of modified stimuli. A wider range of perceptual results (perceptual spaces, preference spaces and merits) obtained for the modified sounds and the original sounds are compared. It is shown that both adjustment criteria are fulfilled for the adjusted frequency resolution equal to 4 Hz.