Search Results

This paper deals with recent advances in acoustic experimental methods and especially acoustic imaging. The paper covers two areas of interest to acousticians. In the first part, it is explained how near-field acoustic holography (NAH) can be extended with beamforming in the near-field, focalization. The combination of the two methods is providing now a source localization solution with a good spatial resolution over the complete frequency range without the burden of measuring a large number of points as would be required if only NAH was used. In the second part of the paper, a method is described that goes one step beyond source localization. In this part is explained how source localization techniques in conjunction with artificial excitation of the structure can provide information on the internal sources of the structure.

To consider the acoustic quality in car design, a scientific methodology is developed in order to give an objective notation. To obtain a good correlation between the subjective and objective judgments, the first point is the choice of recording points that represent the signature of each sound sources that the human ear detects in space. Then, the information about the sound quality is extracted from signals with the computation of different appropriate parameters like “shock balance” and “roughness”. From these metrics, a notation system similar to a neural network gives a single note. At last, the processing of parameter is different for engine in stationary or run-up conditions.