Indian Journal of Science and Technology

Abstract

Understanding an acoustic guitar by analyzing music notes has been the focus of proposed work. It started with calculation and verification of octave relationship of frequencies along frets of a string. The mathematical analysis of frequency triggered the curiosity to analyze music notes in cepstral domain. Cepstral domain was helpful to estimate the impulse response ie body response of music note played on that fret. Truncating the samples for body response, gave excitation signals. Ultimately, convolution of this estimated impulse response and the separated excitation signals resulted into synthesized notes. To get the highly correlated synthesized notes, the number of samples in a window was varied. The number of samples giving maximum similarity will be the optimum number of samples for that music note. They vary from fret to fret. So the name is Adaptive Cepstral Domain Windowing Method (ACDW). The size of the window is changed. The algorithm is run for 25 different values of samples, ranging from 50 to 300. Finally, the best one is chosen for synthesis of music notes. Objectives: The focus of the work is estimate the guitar body response by using cepstral domain. Methods/Statistical Analysis: The guitar notes for all twenty frets of all six strings have been recorded with 16 kHz as the sampling rate. This resulted into database of 120 notes for each playing style. The researchers have proposed different methods to find the impulse response of guitar notes. One method includes recording the impulse response by pulling the string till it breaks. Another one is hammer method. The work proposed here uses signal processing technique such as cepstral domain to find the impulse response. The synthesis is been carried out to check if the estimated impulse response can be used to synthesize the music note. Findings: Many scientists have modeled acoustic guitar notes. There are various methods for finding the impulse response as well. Though the cepstral domain approach is commonly used in speech synthesis, this is used for music notes in unique way to find the body response without breaking the guitar strings. Application/Improvements: The method is used for finding the body response of acoustic guitar. The work is focused to new approach towards music note synthesis.

Keywords: Acoustic Guitar, Adaptive Window, Body Response, Cepstral Domain