Research On Vibration Property Of Paulownia Wood For The National Musical Instrument Forecast Model

Paulownia wood is main material used to make Chinese national musical instrument.Acoustical quality of instrument greatly depends on wood vibration property.To explore the transition of subjective evaluation to objective evaluation,the experiment choose the typical Chinese national musical instrument(lute,yueqin,ruan)as study objects.The vibration property of sound board material(The main influence index:specific elastic modulus,elastic modulus and shear modulus ratio,acoustic radiation damping coefficient,acoustic impedance),resonance board(The main influence index:specific elastic modulus,elastic modulus and shear modulus ratio,acoustic radiation damping coefficient,acoustic impedance),resonance component(The main influence index:specific elastic modulus,elastic modulus and shear modulus ratio,acoustic radiation damping coefficient,acoustic impedance)and wood resonant(The main influence index:specific elastic modulus,elastic modulus and shear modulus ratio,acoustic radiation damping coefficient,acoustic impedance)was measured.Based on the previous work of my two tutors and their research team,multivariate statistics method,economics prediction method and intelligent control method were utilized to study the relation of the acoustic vibration performance parameters of sound board material,resonance board,resonance component,wood resonant and instrument acoustical quality,as well as the above four stages the measured sound vibration performance parameters of the correlation between the large number of analysis on the basis of the production of the three instruments each nine,according to the expert subjective evaluation of the score,from high to low divided into three grades,in which,grade 1?3 were the high-grade musical instruments,grade 4?6 were the mid-range instruments,grade 7?9 were the low gear musical instruments.Pick of the most significant factors influencing the acoustic quality of musical instruments,the dynamic modulus of elasticity E/?,elasticity modulus and shear modulus ratio E/G,acoustic damping coefficient R,and acoustic impedance as input,and select the sound board material corresponding to the experts to assess the instrument of high,medium and low three grades as output.The instrument acoustical quality prediction model was trying to built based on the detection of national instrument sound board material,which can predict national instrument quality from production source.Prediction method of national instrument acoustical evaluation system parameters were investigated to build the prediction model of national instrument acoustical quality and establish an evaluation method.(1)According to the order of the production process of the national musical instruments,the tested bodies were divided into two groups according to the material of the sound board material-resonance board,resonance board-resonance component,resonance component-wood resonant,sound board material-wood resonant.Pearson simple correlation analysis was used to investigate the relation between the two parameters of parameter and parameter of each stage of the instrument production process.The results show that the correlative coefficients of national musical instrument productive process parameters are different from each other.With proceeding of the productive process,the difference between the correlative coefficients of the two indexes declines,and the correlation also recedes.(2)The vibration characteristics of sound board material-resonance board,resonance board-resonance component,resonance component-wood resonant,sound board material-wood resonant were grouped,the vibration characteristics of the adjacent test object in each production stage as a pair.Typical correlation analysis method was used to investigate the correlation between each pair of parameters in each stage of national musical instrument production process.The results show that national instrument wood resonant vibration property highly depends on sound board material.The maximum value of typical correlation coefficients of sound board material and wood resonant is the middle value of the four productive steps typical correlation coefficients,which matches the actual situation of the instrument productive process.(3)Consider sound board material-resonance board,wood resonant vibration property as study objects.Typical correlation analysis method was used to build the multiple choices model,which was applied to predict national musical instrument acoustical quality through sound board material vibration property.The results show that the training results of national musical instrument acoustical quality multiple choices model have great difference in different critical value range.The great error indicates that multiple choices model is not suitable for predicting national musical instrument acoustical quality through sound board material vibration property.(4)Consider sound board material,wood resonant vibration property as study objects.BP neural network was used to build the classification model of national musical instrument acoustical quality through sound board vibration property.The results show that the validation error of national instrument classification grade predicted by sound board material vibration property is small,and the classification model is suitable for predicting national instrument acoustical quality classification.(5)Consider the vibration property of national instrument sounding board and wood resonant as study objects,using SVM method,the national musical instrument acoustical quality classification prediction model was built.The results show that the error of classification grade predicted by the vibration property of sounding board material is small.The classification results indicate that the classification model can predict the national instrument acoustical quality.The analysis shows that the accuracy of national instrument acoustical quality predicted by BP neutral network and SVM is high and has an ideal applicability.SVM is a learning method structure risk minimization,the accuracy of national instrument acoustical quality predicted by SVM is higher than BP neutral network.And SVM method has advantages to solve small sample prediction.