Application of Acoustical Holography on Noise Analysis for Transmission System

• Main Authors: Bo-Shen Wu, 吳柏賢
• Other Authors: Gee-Pinn James Too
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/83926354990942828975

碩士 === 國立成功大學 === 系統及船舶機電工程學系碩博士班 === 94 === In the present study,noise analysis of the chain transmission system in automobile is explored,First, Fast Fourier Transform and Short-Time Fourier Transform are two kinds of analytical methods used to carry out time domain analysis,frequency domain analysis and time-frequency domain analysis of analysis for stationary and non-stationary signals,The purpose of this study is to find out the possible reason for causing the chain transmission to produce the noise？ After confirming the reason why the noise is produced,acoustical holography is implemented by using a surface version of similar source method,The hologram given the chain transmission sound pressure contour distribution maps of overall frequency and each dominant noise frequency,Therefore,the noise source location of each individual dominant noise is extracted from the hologram。 In order to overcome the error of predicting sound pressure within a prediction distance by the plane surface version of similar source method,MUSIC method combined with the similar source method are used for improving the accuracy within the prediction distance,In order to reduce the effect of measuring error and to improve the accuracy of the analysis with plane surface version of similar source method,combined Tikhonov Regularization method and L-curve method are used in the analysis,Also,in order to solve the problem that the number of microphones is insufficient in acoustical holography experiment,a reference microphone is used in the experiment,By using transfer function between reference microphone and measuring microphone,a revised measure phase angle is obtained in the experiment。