关键词: 语音合成, 后置滤波器, 参数自适应, 自然度, 隐马尔可夫模型（HMM）

Abstract: In order to overcome the decrease of speech naturalness resulting from fixed postfilter parameters, the improved speech synthesis with adaptive postfilter parameters is proposed. Short-term postfilter parameters are adapted to variations in spectral flatness that obtained from the speech to enhance the formants of spectrum and a long-term postfilter is used to emphasize the signal components at harmonic peaks and attenuate the discontinuity of pitch. Simulation experiment results demonstrate that the method can alleviate spectral over-smoothing and subjective tests show that the speech naturalness is improved.

Key words: speech synthesis, postfilter, adaptive parameter, naturalness, Hidden Markov Model（HMM）