Innovative synthesizer model for acoustic guitar notes

Abstract

A box-shaped acoustic guitar produces a sound note which is the convolution of excitation source and the impulse response of the soundboard. The soundboard acts as resonator for the note produced at different frets of different strings. Impulse response modeling is commonly used for speech signal. But, it is not used for modeling string instruments. This paper presents the details of impulse response modeling for guitar notes. ADSR modeling and digital waveguide techniques have been very famous in the area of modeling string instruments. The work is focused on impulse response modeling of box-shaped acoustic guitar using cepstral windowing technique. Samples of all frets for finger and plectrum plucked acoustic guitar notes are recorded using pure audio recorder. Analysis is carried out for impulse response for soundboard and the excitation signal of the string for eleven frets for finger and plectrum plucked acoustic notes. Cepstral windowing technique is applied to find the excitation signal and the guitar body response for the corresponding sound note. The number of samples for finding impulse response and excitation signal for that note is variable from fret to fret. Correlation coefficient is used for checking the quality of synthesized sound note. An algorithm is developed for varying the number of samples, and finding the best possible number of samples for synthesis is proposed for impulse response modeling.