Análise do espectro de frequências em cordas de guitarras quando excitadas em diferentes posições

Abstract

The sound of the musical instrument is important for music, because it can change the way the music is made and interpreted by the listener. To obtain an improvement in the sound, the musician uses some tricks, such as sound effects with the help of electronic equipment. However, when it comes to the guitar, there is a way to change the sound of the guitar strings in a purely mechanical way, by means of the position where the string is plucked. The main objective of the present work was to analyze the excited frequencies in guitar strings, from their point of excitation, by means of theories that describe the behavior of the strings, as a means of substantiating the analysis. This analysis was carried out in an experimental way, consisting in exciting the guitar string in five determined positions and capturing the sound produced by the guitar string through an audio interface. With the help of software, the sound coming from the guitar was recorded, without modifications, in which the guitar sound, that was in the form of a sine wave, was transformed into graphs of point frequencies by different sound intensities. Each position was analyzed to reach a conclusion about the factors that make possible the changes in the generated harmonics and their amplitudes. In the analysis, it was found that for the excitation positions closest to the extremity there was an increase in the amount of harmonics, which have high frequencies, and higher intensities. The string diameter also interferes in the frequencies generated, and as there is an increase in the diameter of the string, less harmonics are generated. [resumo fornecido pelo autor]