It is proposed to develop the first commercial code for the application of Nearfield Acoustical Holography (NAH) to arbitrarily shaped interior and exterior spaces. NAH is a powerful noise control tool that allows sound fields to be visualized in three dimensions based on sound pressure or surface velocity measurements over two-dimensional surfaces. To-date, however, NAH has been applied commercially only in planar geometries and based solely on sound pressure measurements. If NAH is to be used to visualize sound radiation into aircraft interiors, or from the casings of aero engines, for example, holographic procedures must accommodate arbitrary geometries. Here, it is proposed to use boundary and finite element techniques to perform the NAH sound field projections in arbitrarily shaped spaces. A feature of the proposed work that will enhance its practicality is the allowance for mixed inputs to the holographic process: i.e., either sound pressures, surface velocities or a combination of the two. Another important feature of the present approach is that it makes use of the same codes that are now used for acoustical prediction and optimization. Thus, the result of this project will be an integrated tool for acoustical design, optimization and experimental analysis.
Potential Commercial Applications:The Boundary Element Method implementation of Nearfield Acoustical Holography will extend the capabilities of our current Boundary and Finite Element program, COMET/Acoustics. This research will lead to a product that will enhance coupling between numerical and experimental methods and will bring the first commercial implementation of Nearfield Acoustic Holography to the aerospace, defense and automotive industries.
