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Research on Algorithm of Sound Source Identification Based on Cross-spectral Beamforming with Exclusion of Autospectra

YANG Yang;CHU Zhi-gang;NI Ji-min;WANG Wei-dong

2011, 31 (4): 145-148. DOI: 10.3969/j.issn.1006-1355-2011.04.034

Abstract （2632）

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The principle of cross-spectral beamforming with exclusion of autospectra is analyzed based on spherical wave assumption. The result shows that the interference from the self-noise in each microphone channel is suppressed and the accuracy of sound source identification is improved by excluding the auto-spectral elements from the cross-spectral matrix. Furthermore, the algorithm of sound source identification is designed and the corresponding sound source imaging software is developed. The sources in the source plane are identified accurately. Additionally, the correctness of the designed algorithm and practical applicability of the developed software are tested and verified by an example. Based on this, the noise sound source identification test of an engine on a bench is made under the rated speed condition. The result shows that the noise at the engine head is mainly from the radiation noise of the air compressor exhaust outlet and the engine body at the upper left of the crankshaft pulley, and the noises of the left side and the right side of the engine are both mainly from the radiation noise of the engine block and the oil pan.

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Abnormal Noise Source Identification and Control of Motorcycle under Idle Condition

CHU Zhi-gang;YANG Yang;JIANG Zhong-han

2011, 31 (4): 89-92. DOI: 10.3969/j.issn.1006-1355-2011.04.021

Abstract （5169）

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Utilizing sound intensity method, source separation method and selective sound intensity method comprehensively, the abnormal noise source of motorcycle under idle condition was identified. The production mechanism and transmission of the abnormal noise was analyzed. The results show that the frequency ranges from 891Hz to 2239Hz and the radiation noise of exhaust muffler heat shield is the dominate source and the impact to the muffler internal partitions by exhaust airflow is the root reason. The abnormal noise can be eliminated effectively by strengthening the connection stiffness of the muffler internal partitions.

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《Study on Induction Noise Control for Air Compressor of an Idling Truck》

WANG Liang;LUO Hong;CHU Zhi-gang;WANG Wei-dong

2009, 29 (6): 147-150. DOI: 10.3969/j.issn.1006-1355.2009.06.147

Abstract （3140）

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Many noise source identification measures show that the source of the abnormal noise of an idling truck is the air compressors induction noise. Based on this, the expansion muffler and interference muffler are designed on the inlet duct of the air compressor. The acoustic finite analysis for the inlet system including muffler, air cleaner and the inlet duct of the air compressor and the engine shows that the muffler has remarkable transmission loss. Base on these, the samples for the expansion muffler and the interference muffler are made and tested in the truck for verifying noise control effect. Result shows that the designed muffler can control the noise effectively and the interference muffler is better than the expansion one. Considering the shortage of the designed interference muffler and the characteristic that the air compressor shares the same inlet system with the engine, an engineering design for the interference muffler is present. The acoustic transmission loss and the noise control of the engineering one are also notable. Although the engineering interference muffler is a litter worse than the interference one, it avoids the shortage of the interference one that the duct is too long to choking. Lastly, an intake time testing for the gas storage is done with the engineering interference muffler, though the intake time is a bit longer, it is still better than the national standard.