Spectral correlates of voice open quotient and glottal flow asymmetry : theory, limits and experimental data

The effects of voice open quotient and glottal waveform asymmetry are studied in the spectral domain. The hypothesis that the amplitude difference of the first and second harmonics of the inverse-filtered voice signal (H1*-H2*) is a reliable spectral correlate of the open quotient is tested. Theoretical arguments and experiments are reported. In the theoretical part, analytical formulas are derived for the spectrum of several models (LF, R++, KLGLOTT88). Then it is shown that H1*-H2* is generally dependent on both open quotient and asymmetry. Domains for open quotient, asymmetry and H1*-H2* variations are given. In the experimental part, examples of voice and singing signals are analyzed. It is shown that a significant part of the spectral measurements obtained are out of the scope of the models studied.