Application research on NAH for identification of plant sound source

The basic theory and applications of near-field acoustic holographic (NAH) technique were introduced in this paper. The mechanism of acoustic emissions of water stress in plant was studied and a measurement analysis method was suggested. The acoustic emission signal in the plant was regarded as point sound source, and the cylindrical surface-spherical surface non-conformal acoustic holography transform technology based on BEM was adopted to study the identification and localization of sound sources of water stress in the plant. Fewer receiving layers were used to collect the most typical space sound field information, and to make them play the main role in the plant sound field analysis. Aiming at the character of acoustic emission signal, the method of choosing wavelet function was given in the paper. In order to improve the identification accuracy of the sound source, the method of wavelet analysis was used by combining with acoustic holography.