Identification of sound source in a car based on the near-field acoustic holography

摘要

In this paper an experiment was carried out to identify the noise source (a loundspeaker) located in the interior sound field of a car using the near-field acoustic holography (NAH) based on the equivalent source method (ESM). The aim of the experiment is to examine the influence of reflected sound on the NAH reconstruction and seek an appropriate way to suppress this influence. The results showed that the reflected sound can be regarded as a kind of measurement error when the ratio of reflected sound to radiated sound is small, and the sound field can be reconstructed directly by NAH without any pretreatment. However, when the ratio of reflected sound to radiated sound is big, the sound field separation technique has to be adopted to preprocess the measurement data. In this paper the double-layer sound field separation technique based on the ESM is used and the sound field radiated by the source is separated from the mixed sound field successfully. Then the reconstructions based on the mixed pressure and on the separated pressure are compared to demonstrate the necessity of the separation process.