Identifying of interior noise sources in a vehicle cabin using the inverse method

The inverse method can be used to identify the interior noise sources in a car cabin which is important in the design of effective active or passive noise control treatments. However, in order to effectively utilise the inverse method, several aspects including the condition number of the inverted matrix and estimation error of the reconstructed acoustic field should be considered. In the experiments reported here, the sources of noise in a car cabin during driving were estimated by the inverse method. The interior noise data was measured by an array of 25 microphones installed at the head position of the front passenger seat. The transfer responses are also measured between a loudspeaker at 96 locations in the vehicle cabin and the 25 microphones. First of all, the condition number of the transfer response matrix that must be inverted was investigated and regularisation was applied to improve the conditioning of this matrix. Secondly, to verify the accuracy of the inverse method, a noise source, whose location and source strength were known, was used. The exact acoustic field and the reconstructed acoustic field using the inverse method were then compared. Finally, the locations and strengths of the interior noise sources during driving were estimated from the measured data using the inverse method.