The sounds produced by noise sources, such as engine, tire-road interaction, wind noise, and engine auxiliaries, and transmitted through the air to the cabin are called airborne noise. The acoustic package of the vehicle is designed to provide the desired sound comfort in the passenger cabin following the vehicle target. Here, the acoustic pack of the vehicle act as a barrier in front of the sound wave, reducing its energy by reflecting it toward the source (insulation) or by transforming the sound energy to heat energy (absorption).
The pressure on reducing CO2 emission in Internal Combustion Engines (ICEs) and the requirements to increase range in electric vehicles (EV) always tend to the reduction of vehicle weight. The demand to reduce vehicle weight by changing the material or reducing the size of the acoustic package is always a challenge for the noise, vibration, and harshness (NVH) engineers to determine the trade-off between the vehicle’s NVH performance and vehicle fuel efficiency. Therefore, determining the optimum acoustic pack for the vehicle is an essential factor in guaranteeing customer satisfaction in terms of vehicle acoustic comfort.
This paper presents an experimental method based on transfer path analysis (TPA) to determine the optimum inner dash insulator. First, the critical regions regarding sound transmission from the engine compartment to the passenger cabin were determined with the TPA method. Later alternative dash insulators were produced with and without considering these critical regions. Transmission loss and sound absorption coefficient measurements were performed in the test room and alpha cabin for actual and alternative insulators. Finally, to verify alternative solutions, on-vehicle tests were performed, and the results were compared with the current solution.
Thanks to this new approach, a saving of 21 kg in weight and €26 in cost with respect to the traditional solutions were provided with the alternative solution defined based on this study.