Spectrum characteristics of piano string using Non-Harmonic Analysis

In this paper, we use non-harmonic analysis (NHA), as recently proposed by the author, to analyse the change of frequency of a piano string before tuning. NHA has a high frequency resolution and the influence of the window function is smaller than DFT. The use of A4 for the tuning standard is analysed in the experiment. The observed result is that the variation of the frequency is large before the string is tuned. This is a phenomenon that originates in the way that the vibration of the string combines two large and small elliptic orbits in the direction the string was struck, as was shown by analysis of the string vibration with optical apparatus by Tanaka et al. This paper verifies the change of frequency of the string originating in the elliptic orbit not by using optical apparatus but by recording and analysing the sound of the piano with high frequency resolution NHA.