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The investigation of critical noise sources on pass-by noise tests is demanding development of the current techniques in order to locate and quantify these sources. One recent approach is to use beamforming techniques to this purpose. The phased array information can be processed using several methods, for example, conventional delay-and-sum algorithms, deconvolution based algorithms, such as DAMAS, and more recently, the generalized inverse beamforming. This later method, presents the advantage of separating coherent sources with better dynamic range than conventional beamforming. Also, recent developments, such as Iteratively Re-Weigthing Least Squares, increases the localization accuracy allowing it to be used in a challenging problem as a fast moving source detection, a non-stationary condition. The work will raise the main advantages and disadvantages on this method using a practical case, a passenger vehicle pass-by test.

Prediction of the drive-by noise level in the early design stage of an automotive vehicle is feasible if the source signatures and source-receiver transfer functions may be determined from simulations based on the available CAD/CAE models. This paper reports on the performance of a drive-by noise synthesis procedure in which the transfer functions are numerically evaluated by employing the Fast Multipole Boundary Element Method (FMBEM). The proposed synthesis procedure first computes the steady-state receiver contributions of the sources as appearing from a number of vehicle positions along the drive path. In a second step, these contributions are then combined into a single transient signal from a moving vehicle for each source-receiver pair by means of a travel time correction.

One dimensional linear acoustics network models are commonly used for the acoustic design of intake and exhaust systems. These models are advantageous since they allow the characterization of the scattering matrices for individual elements, independent of the upstream or downstream components. For an intake or exhaust assembly, the individual elements can be combined by a simple multiplication of the individual matrices to assess the propagation characteristics of the whole system under consideration. The determination of the scattering matrix coefficients can be carried out in an analytical, numerical or experimental way. Since the analytical methodologies are limited to uniform or simplified mean flow representation and the experimental two-port determination is expensive and time-consuming, a numerical method using the time domain Linearized Euler Equations is proposed in this paper.

Tire noise has become a predominant contributor in many traffic noise situations nowadays and hence, the demand for accurate tire noise prediction models is high. A rolling tire is experimentally characterized by means of the substitution monopole technique: the running tire is substituted by the non-operating tire covered by monopoles. All monopoles have mutual phase relationships and a well defined volume velocity distribution which is derived by means of an inverse Airborne Source Quantification technique; i.e. by combining static transfer function measurements with operational indicator pressure measurements close to the rolling tire. Models with varying amounts and locations of monopoles are discussed.

The identification of the contributions of airborne noise sources in vehicles in operational driving conditions is still a cumbersome task. Whereas the measurement of the transfer path from possible noise sources to the observer ear locations is efficient and accurate in most conditions, the source strength identification is still a challenging task. This paper presents the basic concepts of a new source quantification technique based on acoustic pressure measurements close to the operating sources. The main goal of developing a new technique is to achieve a faster and more economic method as compared to existing methods.

The reported investigations aimed at adopting and verifying numerical prediction methods for the determination of the efficiency of engine sound shields. An extended measurement series and parallel Boundary Element calculations were conducted on a simple engine simulator with various engine shields. The effect of the shields was expressed in terms of spatially averaged, narrow band Insertion Loss spectra. It was found that the efficiency of sound shields is determined by complex interactions between the source and its surroundings. These effects could be better understood and reasonably well predicted by using the BE method. The relative IL quantity can be calculated more accurately than the absolute sound field descriptors themselves.