Noise source identification with increased spatial resolution used in automotive industry

Abstract

Delay and sum Planar Beamforming has been a widely used Noise Source Identification Technique for the last decade. It is a quick one shot measurement technique being able to map sources that are larger than the array itself. The spatial resolution is proportional to distance between array and source and inversely proportional to wavelength, thus the resolution is only good a medium to high frequencies. Improved algorithms using iterative de-convolution techniques offers up to three times better resolution. The principle behind these techniques is described in this paper, as well as measurement examples from the automotive industry are presented.

Low Complexity Modeling of Cross-Spectral Matrix and Its Application in the Non-Synchronous Measurements of Microphones Array

“…The number of measurement points for NAH is supposed to be very dense at high frequency. The interpolation errors are fairly high when the space of the array grid is longer than half a wavelength [24], [25]. The super-resolution of NAH requires a large and high-density array.…”

Loudness calculation procedure to study electronic steering column lock noise measurement

“…In recent years, all kinds of vehicle manufacturers, for example, military, aircraft and mainly automobile industries, have noise reduction and control as one of the mail goals due to the increasing requirements for low noise emission. In an effort to decrease and control the interior noise and levels of vibration of not only the above-mentioned vehicles but also other equipment, devices and machines, many techniques have been developed: 1 noise source identification (NSI) techniques [2][3][4][5][6][7][8][9][10] and active and passive control methods. [11][12][13][14][15] In particular, passive controls can benefit of the use of innovative materials, such as piezoelectrics, shape memory alloys, 11 magnetostrictive materials 12 and chiral unit cells, [13][14][15][16][17][18] and their mechanical properties can be designed within very large range of modulus and Poisson's ratio values.…”

“…Christensen and Hald 7 worked on a sound field captured by an array of microphones. They used a standard delay-and-sum beamformer whose resolution is limited to around one wavelength, Gade and Hald 8 highlighted that a refined beamforming technique based on different algorithms, for instance, non-negative least squares (NNLS) and deconvolution approach for mapping acoustic sources (DAMAS), might be applied to increase the spatial resolution. A particular technique is the moving source beamforming, a useful technique for noise sources which are in motion, for instance, a car pass-by, an aircraft fly-over and others.…”