55th Meeting Acoustical Society of America Session 2aAAc: Architectural Acoustics 2aAAc11. Active playback of acoustic quadraphonic sound events Active Playback of Acoustic Quadraphonic Sound Events

The reconstruction into a cinema hall or a smaller room, of a sound event which has been previously recorded in a different acoustical environment is an interesting and still open acoustical problem. A new method for hi-fi multi-channel audio playback based on the general solution of the acoustical inverse problem is here proposed. This is implemented as a general feed-forward redundant control system where the number of acoustical signals to be reconstructed is greater than the number of the control signals feeding one or more loudspeakers working as active boundaries of the virtual playback room. This way an optimal and stable solution via a least square approach is obtained. This control system can be implemented even for complex configurations thanks to acoustic quadraphony: the application of sound intensimetry to audio technology recently developed within the IST-2-511316-IP European project denominated IP-RACINE. After a short explanation of the model theory, the experimental application to the simplest case of 1-D confined field is here presented and some experimentally obtained results are shown

Reactive acoustic intensity for general fields and energy polarization

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The Effect of the Excitation Modelling in the Parameter Estimation of Nonlinear Rolling

In this paper the effect of the excitation modelling on the fitting capability of the nonlinear roll motion equation to experimental data is studied. Several frequency dependent and constant effective wave slope coefficients are derived for five different scale models corresponding to different ship typologies by a Parameter Identification Technique. The frequency domain behaviour of the obtained coefficients is discussed and compared with linear diffraction (strip theory) results and I.M.O. suggested values. It appears that a mathematical modelling with constant damping parameters and frequency dependent excitation could give very good results. As regards the excitation parameters, a common trend for slender bodies is evidenced