A Process to Characterize the Sound Directivity Pattern of AVAS Speaker 2023-01-1095

The speakers in acoustic vehicle alerting system (AVAS) play a crucial role for pedestrian safety. Considering their directivity pattern is critical for accurately simulating the exterior sound field of electrical vehicles. This paper proposes a new process to recover the sound directivity pattern of AVAS speaker. The first step of the process is to perform an acoustic testing to measure the sound pressure data radiated from the speaker at a certain number of microphones. Based on the geometry of the speaker, the locations of the microphones and the measured sound pressure data, an inverse method, called pellicular analysis is adopted to recover a set of vibration pattern of the speaker surface. The recovered surface vibration pattern can then be used in the full vehicle model as an excitation for simulating the exterior sound field. The process is validated by both numerical data and real testing data. In all the examples, the microphones are categorized as two groups. One group of microphones are treated as input for the inverse estimation. Another group of microphones are used for validating whether the recovered vibration pattern can generate accurate sound pressure level at different locations. It is found the proposed process can obtain the vibration pattern of the speaker and its sound field accurately. The robustness of this process regarding the number of microphones, errors in the measurement of microphone locations and sound pressure data is also investigated.