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This paper describes a measurement points' placement technique for the sound source identification using inverse acoustic analysis. In order to reduce noise in NVH problem for various kinds of machines including small size engine, it is necessary to identify the sound source. The inverse acoustic analysis is a technique that is effective for the sound source identification.[1,2] The inverse acoustic analysis identifies a surface vibration of an object by measuring the radiated sound and solving the inverse problem. Nakano et al. researched about the location of sound pressure measurement points for accurate improvement.[3] They clarified that the sound pressure measurement points on the concentric circle gave more accurate surface vibration than the measurement points on the square lattice.

This paper describes the comparison method of input powers and contribution rates from vibration sources to a small power generator's enclosure represented by a thin-walled plane structure determined by Statistical Energy Analysis (SEA) and Transfer Path Analysis (TPA). In the pursuit of efficient ways to analyze the design dynamics of small machines such as a small power generator, it is important to identify information and dynamics of input power sources during machine operation. SEA and TPA are two of the most efficient methods in identifying the dynamics of a structure during machine operation. SEA is used for systems with many resonant modes, and predicted results are based on space averages. On the other hand, TPA is based on estimation of a frequency response function between an excitation point and a response point. In this study, we proposed a method to compare SEA evaluated by power injection method and TPA evaluated by matrix inversion method.