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Vehicles with electrified powertrains are being introduced at an increasing pace. On the level of interior sound, one is often inclined to assume that NVH problems in EV have disappeared together with the combustion engine. Three observations demonstrate that this is not the case. First of all, only the dominant engine sound disappears, not the noise from tire, wind or auxiliaries, which consequently become increasingly audible due to the removal of the broadband engine masking sound. Secondly, new noise sources like tonal sounds from the electro-mechanical drive systems emerge and often have, despite their low overall noise levels, a high annoyance rating. Thirdly, the fact that engine/exhaust sounds are often used to contribute to the “character” of the vehicle leads to an open question how to realize an appealing brand sound with EV. Hybrid vehicles are furthermore characterized by mode-switching effects, with impact on both continuity feeling and sound consistency problems.

This paper presents an on-line, order-based roughness approach for vehicle engine sounds. This new algorithm reconstructs the sound envelope per critical band in an analytical way from the order amplitudes, phases and frequencies. The most time-demanding operations of the classical roughness models are no longer needed, rendering the algorithm extremely fast and applicable in real-time. Another interesting characteristic of this new algorithm is the unique link which is established between the roughness and the engine order components of the sound. Sound engineers can easily identify which order components need to be modified to reduce a roughness problem.

Aircraft noise modeling aims to provide designers with computational tools that allow exploring the design parameters domain early in the design and development process. A number of modeling techniques are available for acoustics and vibration prediction, but in order to define objective targets for sound quality perception, dedicated tools are still needed to correlate structural models and design modifications with human perception of sounds. This paper presents a model-based sound synthesis concept for interior and exterior aircraft noise that allows interactive, real-time sound reproduction and replay. The proposed approach is presented through two application cases: jet flyover noise and turboprop interior noise.

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.

The Transfer Path Analysis method is at the core of the Source-Transfer-Receiver approach to address noise and vibration problems. While originally developed for analyzing structure-borne noise transmission, its application range has been extended to airborne noise. Various frequency and time domain approaches have been developed with a focus of supporting specific design engineering problems. One such application is the source contribution analysis in the context of vehicle pass-by-noise. The upcoming changes in the pass-by noise regulation will not only require more complex tests in different conditions but most importantly, the new directive will force car manufacturers to further reduce the emitted noise levels of their vehicles.