Leakage Detection Techniques Using Nearfield Acoustic Holography

This paper attempts to explore the possibilities of using various methods of nearfield acoustic holography (NAH) to detect the air/sound leakages from a container by locating the noise sources. The detection capabilities of three different NAH methods are compared. An acoustic source is placed inside the container and the hologram measurement is performed near the surface of the container. The NAH methods are applied on the hologram data to detect and quantify the leakage locations. Reconstructed acoustic pressure and particle velocity results are presented. NAH algorithms are found to work better for the higher input frequency cases. Tikhonov regularization is used to alleviate the singularity in the transformation matrices. However, generalized cross validation over-predicts the Tikhonov parameter for the present geometry. The resolution limitations of the NAH methods with respect to the hologram distance are addressed.