Vehicle manufacturers throughout the world are facing increasingly stringent noise legislation which demands highly refined vehicles and powertrains for compliance. Further to the demanding legislative requirements, an increase in customer awareness regarding high ride comfort has forced additional refinement as regards competitive sound level and sound quality.
In the commercial vehicle market this trend in increased customer awareness is growing ever more apparent, although the expectations regarding noise are, for some applications, justifiably lower than in the passenger car market. Further to legislative compliance and a competitive noise level in dB(A), noise quality issues are increasingly being addressed to satisfy customer demand.
In the passenger car market customer awareness regarding noise has increased to such an extent that in order to satisfy customer expectations engineering desirable sound has become an integral requirement.
In this paper three case studies are presented based on problem focused NVH analysis. Case study 1 presents a tractor noise problem related to legislative requirements. Case study 2 is based on noise reduction of a commercial vehicle diesel engine and is integrated with a complementary section on engine structure design. The third case study is related to passenger car interior noise quality and is integrated with a section on engineering desirable sound.