Analysis/Synthesis of Stringed Instrument Using Formant Structure

In this paper, timbre of stringed instrument is analyzed and the timbre sound is synthesized. Timbre is familiar and looks well known, but it has been unknown even now what an essential factor is. And it is the most important factor for human to distinguish sounds with the same duration, loudness and pitch. The formant structure model for keeping the same timbre is proposed in this paper. The structure proves to be useful for characterizing timbre of an electric bass guitar and an electric guitar. Spectrums of sounds on one string have similar formant structure as far as plucked instruments are concerned. The envelopes are represented by approximate curves of the fundamental and harmonic frequencies among local envelopes. And the relation among strings is expressed by parallel shifting on x-axis in log2 scale. In addition, the tolerance of amplitudes relating with the formant structure model is investigated through some experiments. Moreover, using the formant structure model, an electric bass guitar sound is synthesized and the timbre is evaluated subjectively, and has been got the average score 4.5 by five-grade evaluation, that is, excellent in its quality. In addition, we could arrange the sounds of an electric bass guitar with various atmospheres. The proposed method is so flexible and the tolerance is very high. We have also got similar results about acoustic and electric guitars. In future work, we will expand into general stringed instruments.