Legal requirements and design of exterior sounds for electric vehicles

According to legal requirements, vehicles with an electric engine (electric and hybrid vehicles) have to be equipped with a device to warn pedestrians (AVAS, Acoustic Vehicle Alerting System). Corresponding regulations are or will be in force in the coming years more or less worldwide. The regulations differ for the different regions, complicating the Sound development and vehicle adaptation.For the OEMs the generation of exterior sound offers the opportunity to implement a recognizable, typical Brand Sound. But, the sound emitted to the exterior is partly also audible in the interior. It thus has to be avoided that it reduces the interior Sound Quality and NVH performance and causes strange interior sound effects, since the exterior sound only has to be active up to 20 or 30 km/h.The creation of a sound that fulfills the different legal requirements, implements a Brand Sound and does not reduce interior Sound Quality is a challenging task. In order to do so, complex and sophisticated sound generation algorithms have to be applied, and a proper process has to be used for the design and vehicle adaptation process. For most OEMs the target Brand Sound for AVAS systems is not yet defined, and the standard process only allows to check whether a sound fulfills the legal requirements when a vehicle is equipped with a device and measured according to the legal specifications. This process is tedious, time-consuming, inefficient and costly.In order to solve the conflict between the required fulfillment of legal requirements on the one hand and the wish to implement a Brand Sound on the other hand, plus an easy vehicle adaptation of AVAS an assessment of the conformity of an actually designed sound is directly integrated into the Sound Design Process.