Review of Techniques to Predict the Surface Contributions to Far Field Radiated Sound

Prediction of radiated sound from vibrating structures is required for structural design optimization and effective noise control. Techniques to predict the surface contributions to the radiated sound from a vibrating structure include the supersonic acoustic intensity, the surface contribution method and near-field acoustic holography. Near-field acoustic holography is an experimental methodology to reconstruct the acoustic field on the surface of the structure. The acoustic field is measured close to the structural surface and observes both radiating and non-radiating components in the near field. Based on the techniques for near-field acoustic holography and acoustic radiation modes, supersonic acoustic intensity and surface contribution methods have been developed to identify only those components of the sound field propagating to the far field and to localize the efficiently radiating surfaces of the structure. In contrast to near-field acoustic holography which focuses on sound radiation in the near field, the supersonic acoustic intensity and surface contribution methods are used to predict the surface contributions to the far-field radiated sound power. This paper provides an overview of techniques to predict surface contributions to exterior radiated sound from vibrating structures. The development, methodology, strengths and limitations of the various techniques are discussed. A numerical example to demonstrate the surface contribution method is also presented.