Research On The Vibration Characteristics And Acoustic Quality Of Guitar Strings Under Different Plucking Displacements

The quality of musical instrument timbre directly determines the performance of the instrument.As the influencing factor of the timbre of string instruments,the plucking force has become a problem that the performers attach great importance to.The pluck ing force is related to the plucking displacement,so this thesis takes the guitar string as the research object,and studies the relationship between the vibration and acoustic quality of the guitar string and the plucking displacement from an objective point of view.The research work and achievements in the thesis are as follows:This thesis summarizes the current situation of guitar research,explores the existing problems and research directions of guitar research,and studies the vibration and acoustic characteristics of guitar from the perspective of vibration and acoustics.In this thesis,the structure of guitar is introduced,the dynamic analysis of string vibration is carried out,the simulation experiment is carried out by numerical calculation method,the acoustic system of guitar is introduced and the model is simplified.In order to study the vibration mechanism of guitar strings,a non-contact optical measurement system is built to measure the vibration characteristics of the string mark points when plucking strings.The circular Hough transform is used for image processing to ext ract the central position coordinates of the mark points and synthesize the vibration displacement and velocity curves.The experimental results are compared with the simulation results to verify the experimental results.The experiment displacement and v elocity characteristics of guitar string vibration under different displacement are compared with the simulation results.It is found that the period is in good agreement.Y direction is the main direction of displacement,also in good agreement,while Z direction displacement is relatively small,and the vibration characteristics are not obvious.This thesis analyzes the displacement and velocity vibration attenuation of guitar strings under different displacement,analyzes the acoustic signal in time domain and frequency domain,defines the harmonic ratio,which makes it more convenient and intuitive to compare the changes of harmonic.The guitar strings with different displacement have no stable stage after obtaining the vibration condition,only the att enuation stage,and the attenuation is relatively slow.The larger displacement,the longer vibration duration is.For bare strings,the vibration duration is very short,and the attenuation degree is a little more violent than that of the wound string.However,for twining strings,the vibration duration is longer and the attenuation is slow.This thesis analyzes the change of the first to fifth harmonic components of each guitar string under different displacement.For e1 string,the first to third harmonic components are higher,and the change of harmonic components is not obvious with the increase of p lucking displacement.For b string,the first to fourth harmonic components are higher,and the fourth harmonic component is the highest,and each harmonic component increases with the increase of plucking displacement.For g string,the second and third harmonic components are higher than other harmonic components.For d string,the first to third harmonic components are higher.For A string,the first and second harmonic components are higher.For E string,the second harmonic component is the highest.