This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
The Use of Nearfield Acoustical Holography (NAH) and Partial Field Decomposition to Identify and Quantify the Sources of Exterior Noise Radiated from a Vehicle
Annotation ability available
Sector:
Language:
English
Abstract
Since powertrain noise sources are usually “hidden” within the engine compartment, it is difficult to use NAH to identify those sources and the associated partial radiation fields that together create the exterior noise field of a motor vehicle. Integrated Nearfield Acoustical Holography (INAH) has been developed to address this concern. INAH represents a combination of NAH, reference microphone selection procedures, and coherence techniques. The procedure entails sensing the sources inside the engine compartment by using an array of reference microphones, and then calculating the associated partial radiation fields by using NAH. A key factor in the success of this procedure is the selection of a good reference microphone sub-set. A selection procedure has been developed by combining condition number and coherence analyses. The partial field determination problem has been approached by using both partial coherence and Singular Value Decomposition (SVD) procedures. It has been found that the partial coherence technique maintains a closer relationship with the physical partial fields than does the SVD procedure. In the work discussed in this paper, INAH has been demonstrated through the identification of the hidden sources and the partial fields that contribute to the exterior noise field of a vehicle.
Authors
Citation
Takata, H., Nishi, T., Jiang, W., and Bolton, J., "The Use of Nearfield Acoustical Holography (NAH) and Partial Field Decomposition to Identify and Quantify the Sources of Exterior Noise Radiated from a Vehicle," SAE Technical Paper 972053, 1997, https://doi.org/10.4271/972053.Also In
References
- Hald J. “Use of Spatial Transformation of Sound Fields (STSF) Techniques in the Automotive Industry,” Brüel and Kjaer Technical Review 1995
- Lim T. W. “Actuator/Sensor Placement for Modal Parameter Identification of Flexible Structures,” Modal Analysis 8 1 1 13 Jan. 1993
- Bendat J. S. Piersol A. G. Random Data, Analysis and Measurement Procedures John Wiley & Sons New York 1986
- Hallman D. L. Bolton J. S. “A Comparison of Multi-Reference Nearfield Acoustical Holography Procedures,” Noise-Con94 Proceedings 928 934 1994
- Kompella M. S. Davies P. Bernhard R. J. Ufford D. A. “A Technique to Determine the Number of Incoherent Source Contributions To the Response of System,” Mechanical Systems and Signal Processing 8 4 363 380 1994
- Dignan M. Burke F. “Procedure for the Design of Active Noise and Vibration Control Systems,” Proceedings of the 12th International Modal Analysis Conference 582 589 1994
- Wang P. F. Development of Experimental Model Building Techniques Purdue University, School of Mechanical Engineering 1995