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Acoustic Holography is emerging as a powerful, high-resolution noise source localization technique in this decade. Compared to conventional sound intensity measurement, Acoustic Holography scores because of its ability to provide on-line visualization of acoustic energy distribution of the sources perform measurements during stationary and transient conditions and it is substantially faster and easier. Further, with Near Field Acoustic Holography (NAH) and Beam-Forming (BF) techniques, it is possible to cover wide range of frequencies with reasonable investment. This paper compares and evaluates the advantages of the Acoustic Holography technique with conventional Sound Intensity Mapping for different applications such as noise mapping of a vehicle, noise source identification of engine and other small sized components. It also discusses how this technique can be extended to moving sources such as noise source identification during pass-by.

The acceptance criterion of any vehicle in terms of user comfort invariably depends on the vehicle interior noise and vibration characteristics. The levels of sound energy and structural excitation inside the vehicle compartment measures the amount of annoyance in terms of quality and comfort. For vehicle interior noise abatement and noise treatment, it is desirable to quantify the noise sources by determining the sound power contribution from each vehicle component/panel, acoustic leakages inside the vehicle, body panel vibrations, gearshift lever and steering wheel vibrations. Many a times, it is necessary to arrive at benchmarks or targets for the various sources of noise in order to refine the systems. The present paper describes a methodology for interior noise source identification and its analysis for benchmarking. Two different vehicles of the same class but of different makes were compared and evaluated for interior noise and vibration levels.