Experimental Results of Converted NAH Method

Abstract

Among sound source localization methods, the acoustic intensity (AI) method is widely used in industry. On the other hand, nearfield acoustic holography (NAH) method, which is also a localization method, has not spread to industry use because of its difficulty in measuring high frequency measurement. For high frequencies, the NAH method requires a very large number of measurement points, which results in a prolonged measurement time and very large size. I have proposed a theoretically converted NAH method(1),(2), which uses the extra spatial-domain spectrums in the backpropagating computation of NAH method. This method can measure the sound field using a reasonable number of measurement points even for high frequencies. As a result, the workload of measurement is reduced to the same level as that using acoustic intensity method. In this paper, the theory of the proposed method is explained, and some experimental results are presented to verify this method.