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The effective identification and control of powertrain structure borne harmonic noise is a key to achieve a desired noise quality profile in a vehicle. Much work is being done in this field to refine and develop sound engineering techniques suitable for application at each stage of a vehicle development programme. For prototype development and trouble shooting, transfer path analysis and source identification techniques are in use today with varying degrees of success and application complexity. Investigation tools which are fast, do not require extensive vehicle dismantling and yet provide reliable answers, will be of value to the NVH and sound quality engineer. A new Active Path Tracking method is described which is relatively quick and offers practical confirmation of the influence of identified paths. The method involves the novel adaptation of Active Noise Cancellation techniques to the task of source identification.

The next generation of automotive engines has to meet 2004 emission limits, ideally with improved fuel economy and with noise emission which is at least 3 dBA below the current status. Using both simulation and experimental analysis these challenging requirements can only be fulfilled by clearly defining all key steps in NVH development and by applying suitable technological methods. The development procedure discussed in this paper is characterised by several aspects: two stage prediction procedure fully integrated in the design process, combustion development with a definite focus on noise, a closed loop between simulation and test bed development and consideration of noise in the calibration of engine and drivetrain management systems. Apart from meeting target noise levels, noise quality is the reference parameter which is continuously evaluated by means of the AVL Annoyance Index.