Abstract: In order to describe the voicing cut-off frequency (VCO) contour more accurately,an improved estimation of the VCO contour based on harmonic and aperiodic energies is proposed.In the improved estimation algorithm, the cumulative harmonic and aperiodic energies function is redefined with the weighted factor of the power spectrum. And the morphology filter is applied in the VCO track smoothing section.The result shows that,the more accurate VCO contour can be labeled with the improved estimation algorithm than that with the conventional algorithm on the spectrogram.In the subjective score test,the score obtained from the improved estimation algorithm is also superior to that from the conventional algorithm.The improved algorithm can estimate more accurate VCO contour compared with the conventional algorithm to provide the speech harmonic-plus-noise model application more effectively in the speech coding,synthesis and recognition fields.