The Equations for the Estimation of One Dimensional Structural Intensity in Semi Near-Field

The measurement of structural intensity with the direct finite difference method has some difficulties that third order derivative is needed in the methods. Some researchers have analyzed the measurement errors in far field or in the field for particular boundary conditions. It cannot be applied, however, to the general case to evaluate the measurement value. Therefore, the general solution of bending vibaration was used in the measurement methods, and the equations which express the measurement value in semi near-field was deduced in this paper. These equations are applicable to evaluating the error in any boundary condition.