Vehicle Powertrain Noise Diagnosis Using Acoustic Holography Techniques

New techniques like Nearfield Acoustic Holography (NAH) and Spatial Transformation of Sound Field (STSF) possess all the potential to become widely-accepted tools for powertrain noise analysis in near future. These techniques demonstrate versatility, rapidity and inexpensiveness, which are very important features for faster and cost-competitive NVH development of the powertrain. Yet, there are certain limitations, for example, high-frequency cut-off depending on how small the microphone-grid resolution is, etc.

This paper includes a concise discussion of problems and promises of NAH application for powertrain systems. Portrayals are given of the detailed application of acoustic holography techniques for complete powertrain system noise analysis. An insight into a few algorithms to circumvent the high-frequency cut-off limitations is provided. With the help of spectral plots, sound intensity order waterfalls and surface vector maps, attempts have been made to illustrate how this technique could be advantageously used to diagnose, identify, and characterize significant noise sources in a powertrain system.