Real-time steerable directional sound sources

Warning signal generators in cars are being developed that have the objective to warn vulnerable road users. Several sensor systems exist which are able to reveal the position of the vulnerable road users, which information can be used by the warning signal generator. Based on this information, the signal generator can be designed to generate the specifed warning signal at the location of the vulnerable road user while the acoustic response at other locations is minimized in order to reduce noise pollution. The directional sound beam was realized with an array of controlled acoustic sources. Changes of the relative positions of the vehicle and the vulnerable road user require continuous adjustments of the sound beam. Different methods to generate the sound beam are described and experimental results are shown. Rapid realtime adjustment of the beaming direction is possible even if the beamformer is recomputed everytime a new steering direction is required.