Vibro-acoustic Rendering Methods to Radiate a Uniform Sound Field from a Panel Speaker
* Presenting author
The sound radiated from the usual panel speaker employing the single point excitation is distorted due to the multi-modal response of the regular panel, or the effective range of radiation is limited to very low frequencies. Such problem can be alleviated if an array of actuators are used in the periphery of the panel to control the vibration response for the uniform radiation in a wide frequency range. To achieve the uniform acoustic field, the two inverse vibro-acoustic rendering techniques can be adopted: first, a vibration pattern composed of a virtual speaker and baffle is being created, and, second, the spatial distribution of the vibration is being controlled to radiate the desired sound. Each method is called indirect or direct method. Numerical simulations are conducted on a thin, simply-supported plate, for which the high frequency limit is 300 Hz. The indirect method results the rendering error of -20 dB and the direct method -50 dB. Two methods are afflicted with the instability, particularly in using the direct one. Regularization technique is used to overcome the ill-posedness, that yields the change of condition number from O(1017) to O(104). Input gains are also reduced by 35 dB for both methods.