An accuracy evaluation of the sound power measurement by the use of the sound intensity and the sound pressure methods

Abstract

Because of its plane-wave assumption at measurement points, the pressure method is in essence an approximation in determining the sound power of a source. When using the sound intensity method, the measurement errors are theoretically due only to the finite number and locations of the measurement points. In the present paper, the degrees of measurement errors of the two methods are evaluated using a sound source model that comprises multiple point-like spherical sources placed above an infinitely large rigid floor. Using such a sound source model, it is possible to evaluate the measurement accuracies of the sound pressure and the sound intensity methods because the radiated sound power is exactly calculated for arbitrary distributions of point-like sources. By randomly changing the distribution and phases of the point-like sources, it is possible to evaluate the statistical aspects of errors such as mean, standard deviation, maximum and minimum errors. One application of this source model is a comparison of the sets of measurement points proposed by standards. A new set of measurement points is also proposed.