Correlations between acoustic and electrochemical measurements for metallic corrosion on steel strings used in guitars

The corrosion state of steel guitar strings and their morphology were evaluated according to exposure time to artificial human sweat solution. The instantaneous corrosion rate was evaluated using polarization resistance. Electrochemical impedance spectroscopy was used to measure the strings' state due to corrosion in artificial human sweat solution. Modification of vibroacoustic parameters was analyzed: changes in harmonic content of sound were studied by means of the Fast Fourier Transform and spectrograms. The correlation between corrosion and acoustic measurements was established in the successive stages of corrosion. Thus, the strings' acoustic properties could be modified by means of controlled corrosion processes.