The design of a low-cost directional warning sound system for electric vehicles

Electric vehicle warning sounds are now required by law in many countries due to safety concerns, but this additional noise source may increase unwanted noise pollution. Therefore, the design of an electric vehicle warning sound system that can produce a directional sound field has been investigated. This paper introduces two design suggestions for a system with comparable performance to the conventional loudspeaker array, but at a significantly lower manufacturing and maintenance cost, suitable for wider commercial adoption. The first method utilises a single loudspeaker attached to a length of perforated piping which acts as a directional acoustic radiator, which is analogous to the shotgun microphone. The second approach replaces the standard loudspeaker array with inertial actuators mounted to a vehicle body panel and these are driven to radiate a controlled directional sound field. A simulation based comparison between the suggested configurations and a conventional loudspeaker array of equivalent physical dimensions is presented.