Efficient Interior NSI Based on Various Beamforming Methods for Overview and Conformal Mapping using SONAH Holography for Details on Selected Panels

The present paper describes a set of array-based methods that can provide both a snapshot overview of problematic areas across the panels of a car cabin and perform efficient analysis of details of a noise problem. The snapshot overview is obtained with Beamforming, while detailed analysis of problematic areas is performed with a small planar single-layer or double-layer array in combination with SONAH holography. Using the SONAH algorithm for patch near-field acoustic holography, all sound field parameters can be estimated directly on the irregularly shaped panel surfaces. All the array measurements can be performed very efficiently by the use of a position measurement system integrated with the array. Panel geometry can also be measured using the position measurement system. The paper gives an overview of the different methods and presents results from a case study.