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One Method of Acquiring Radiated Sound Based on Spatial Transformation

It is found that the radiated sound of sources in external space can be obtained from results of the near-field space. A new theory for obtaining the radiated sound by any sources in a specific space is proposed — Near-field Acoustic Transformation theory (NAT). The NAT theory is explained by the reciprocity principle of sound propagation. When the far-field directivities of the sound sources need to be obtained, the sound in the source space V is plane wave, and the obtained sound source direction is exactly opposite to the propagation direction of plane wave in V. The range that can be measured by NAT method is further analyzed in free-field, shallow water and reverberation pool. This theory does not need the shape and geometry information of sound sources, and has nothing to do with the sources’ material and directivity. It can obtain the free-field radiating sound and directivity of any sound sources in space V. NAT can be applied to reverb conditions. The measuring environment is not limited to free-field conditions. This method provides a new idea for solving the problem of sound radiation measurement in complex environments.