Technical Paper “Designing Sound for Quiet Cars”, published by SAE and presented at ISNVH 2016. Full name: the 9th International Styrian Noise, Vibrations and Harshness Conference 2016 held in Graz, Austria.
The paper outlines the current challenges and available methods to design sound fulfilling functional requirements for enhancing pedestrian safety of electric vehicles, subjective aesthetic requirements to the acoustic appearance as well as upcoming legislation in an international context.
The quiet nature of hybrid and electric vehicles has triggered developments in research, vehicle manufacturing and legal requirements. Currently, three countries require fitting an Approaching Vehicle Alerting System (AVAS) to every new car capable of driving without a combustion engine. Various other geographical areas and groups are in the process of specifying new legal requirements.In this paper, the design challenges in the on-going process of designing the sound for quiet cars are discussed. A proposal is issued on how to achieve the optimum combination of safety, environmental noise, subjective sound character and technical realisation in an iterative sound design process. The proposed sound consists of two layers: the first layer contains tonal components with their pitch rising along with vehicle speed in order to ensure recognisability and an indication of speed. The second layer contains broadband elements that ensure audibility when specific frequencies are masked by environment noise.