Holistic sound package design for optimal NVH and carbon footprint of a BEV

Vehicle sound packages are usually designed to provide a given level of vehicle NVH comfort, under weight and cost constraints. Optimal comfort results can be obtained by considering the interaction of all the parts as a full physical system. So far, extensive research has already been performed and published on optimizing vehicle sound packages to achieve effective noise reduction at lowest cost and weight. Nowadays, due to the urgency of the transition to carbon neutrality, sound packages must also address the reduction of the full vehicle life cycle carbon emissions. Sound package components should use materials that have a low emission impact during production and that are suitable for recycling at the end of the vehicle’s life. This entails reconsidering the material solutions chosen for the sound package as a whole, rather than for each individual component. This article describes the design process of a sound package involving NVH, sustainability, and weight/cost requirements. The study examines how interior and exterior trim components were combined to achieve both optimal NVH and polymer rationalization, through the introduction of mono-material parts and focusing in particular on the use of a new polyester fiber-based floor decoupler, which achieves comparable NVH performance to polyurethane foam without affecting static compression. The article summarizes the vehicle-level performance related to NVH, sustainability, and weight for three sound packages prioritizing either NVH or sustainability or weight/cost, including a breakdown to analyze the contributions of various components to the overall outcome. A simple metric is introduced to evaluate sustainability, including material, production, use and end-of-life related GWP emissions. The NVH evaluation involves measuring airborne transfer functions, followed by indoor road noise tests. NVH improvements were achieved without an increase in weight, and weight reduction was also possible without negatively impacting NVH performance, both results enhancing the carbon footprint.