A Case Study Comparing Active Vs. Passive Enablers for Vehicle Interior Noise Reduction 2023-01-1044

Excessive in-vehicle road noise can lead to increased driver fatigue and an overall degradation on vehicle interior sound quality. Broadband noise can interfere with the ability of vehicle occupants to carry on a conversation or detract from the vehicle audio system perceived sound quality. Additionally, tonal noise (such as that often induced through excitation of the tire cavity resonant frequencies) can lead to general lack of perceived vehicle quality. Though these issues are not new, they have become much more prevalent with electric vehicles which lack the masking noise traditionally provided by internal combustion engines. The implementation of enablers on a luxury sport utility vehicle is used to illustrate the development process for reduction of road noise. The vehicle in this case study was launched into production with two tuned mass dampers for reduction of low frequency noise road noise content which was amplified by frame modes. Additionally, resonators were integrated into the wheels (rims) to address the dominant cavity resonance frequency. The results of this successful implementation are illustrated herein. The advent of active road noise cancellation (first introduced into production in 2019) presented new options for the mitigation of unwanted road noise content. An RNC (road noise cancellation) system was integrated into the case vehicle to assess its performance relative to the passive enablers listed above. This production representative (embedded software solution) RNC system utilized the vehicle’s existing audio system for creation of active noise to cancel noise content which was predicted using accelerometers mounted to the vehicle chassis. A comparison of in-vehicle noise indicated a significant reduction at low frequencies (at all seating locations) when utilizing the active noise control solution. These noise improvements are coupled with a vehicle mass reduction of greater than 4 kg, when compared to the passive enabler solution.