Cepstrum-based estimation of resonance frequencies (formants) in high-pitch singing signals

The estimation of the vocal tract resonance frequencies from acoustic voice signals has been widely employed and various methods have been proposed. Among them, a number of cepstrum based techniques have been implemented to disentangle the voice’s spectral envelope from the harmonic components. Noticebly less research has been conducted for voices with higher fundamental frequency, as in singing (e.g. soprano voices). In such cases, the estimation of the spectral envelope is affected by the presence of cepstral rahmonics, which are interleaved with spectral envelope estimation. In this paper, some new techniques based on cancellation of rahmonics, rather than hard liftering, are proposed and examined for their effectiveness in maintaining the spectral envelope information. Both straightforward implementations and iterative procedures are considered and simulation results for various configurations of f0 and formant frequencies are presented. These preliminary examinations allow the evaluation of effects of various acoustical and signal processing factors on estimation accuracy and assess the feasibility of the proposed approaches for use with high fundamental frequency signals, such as singing, and in other similar fields of interest in musical acoustics.