High-Accuracy Frequency Analysis of Harmonic Signals Using Improved Phase Difference Estimation and Window Switching

Accurate frequency tracking of harmonic signals is an essential process for analysis of musical instrument and singing sounds. For fine frequency estimation, we propose two methods for enhancement of the phase difference estimation (PDE). The first method is improved PDE that maximises the signal level at the frequency estimation position, which is effective especially at low signal-to-noise ratio (SNR). The second method is window switching that minimises the effects of harmonics by suppressing their side-lobe levels, which is effective at high SNR. Window switching is also applicable to existing fine frequency estimation methods as well as the PDE and improved PDE. Experimental results and application examples show that the proposed methods show meaningful improvements over the PDE and are effective for high-accuracy frequency analysis. The proposed methods can be adopted as a module for sound analysis and processing tools and software, which are expected to contribute to the comprehensive analysis of musical signals.