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A key issue in noise emission studies of noise producing machinery concerns the identification and analysis of the noise sources and their interaction and radiation into the far field. This paper presents a new acoustic measurement technique for noise source identification in stationary applications. The core of the technology is a handheld measurement instrument combining a position and orientation tracking device with a 3D sound intensity probe. The technique allows an on-line 3D visualization of the sound field while moving the probe freely around the test object. By focusing on the areas of interest, troublesome areas can be identified that require further in-depth analysis. The measurement technique is flexible, interactive and widely applicable in industrial applications. This paper explains the working principle and characteristics of this new technology and positions it to existing methods like traditional sound intensity testing and array techniques.

In the context of the reduction of traffic-related noise the research reported in this paper provides tools that could be used to develop low noise tyres. Two measurement techniques have been analyzed for exterior noise radiation characterization of a loaded rotating slick tyre on a rough road surface. On one hand sound pressure measurements at low spatial resolution with strategically placed microphones on a half-hemisphere around the tyre/road contact point have been performed. This technique provides a robust solution to compute the (overall) sound power level. On the other hand sound intensity measurements at high spatial resolution by means of a scanning intensity probe have been performed. This technique allows a more detailed spatial visualization of the noise radiation and helps in getting more insight and better understanding of the acoustical phenomena.