DETERMINATION OF THE DIRECTIVITY OF A PLANAR NOISE SOURCE BY MEANS OFNEAR-FIELD ACOUSTICAL-HOLOGRAPHY .1. THEORETICAL BACKGROUND

The theoretical basis of the application of the technique of near fiel d acoustical holography to the measurement of the directivity of a pla nar noise source is discussed. Problems arising from the application o f the techniques are identified. These arise primarily from the need t o work with sampled data over a limited aperture size, as opposed to t he continuous function assumed in deriving the basic theory. Technique s for overcoming these problems are suggested including the use of dat a windows and k-space filtering. A particular problem that is identifi ed is the need to generate data points in k-space other than those cor responding to actual samples. Techniques based upon interpolation in k -space are proposed in order to overcome this problem.