本論文基於HTS的頻譜HMM模型及自行建立的波形包絡模型，來研發一個曲笛聲音的合成系統。首先使用STRAIGHT來分析各個曲笛樂句錄音的基頻軌跡及作自動標音；使用HTS軟體來訓練頻譜HMM模型及決策樹；再對各音符的波形包絡作DCT轉換，然後以前後文分類後算出的平均DCT向量作為包絡模型。在合成階段，先令HTS作笛聲合成，接著則以我們程式產生的F0軌跡去取代HTS所產生的，再以包絡模型DCT向量還原出的包絡曲線，去調整HTS再次合成的波形包絡，如此就可合成出音高正確且比較自然的曲笛聲音。然後，我們進行頻譜誤差的量測及聽測的評估，結果顯示，作F0取代和波形包絡調整後的合成曲笛樂曲，在自然度和品質上都會比原始HTS合成的笛聲好。

In this thesis, a system to synthesis Chinese-flute sound is developed. In fact, the system is based on the HMM (Hidden Markov Model) models of HTS (HMMs trained by the HMM-based speech synthesis system) software and the waveform-envelope models constructed by us. In the training stage, STRAIGHT was used to analyze the pitch contours of the Chinese-flute recording, and the pitch contours are used to label the pitch symbol of each note automatically. Next, HTS was used to train the HMM models and decision trees. Also, DCT (Descrete Cosine Transform) transformation was performed for the waveform envelope of each note. Then, the waveform-envelope model is obtained by averaging the DCT vectors collected from each context class. In the synthesis stage, the HTS software is first commanded to synthesize the Chinese-flute sound of a score. Then, the pitch contours of the notes are replaced by the pitch contours generated by our program. Next, the waveform-envelope of each note’s signal resynthesized by HTS is modified according to the envelope curve generated by the envelope model. Conseqently, the pitchs of the synthesized Chinese-flute notes become correct and sound more natural. By using the synthetic and recorded sound files, spectrum error was measured and listening tests were conducted. The results show that after replacing pitch contours and modifying waveform-envelopes, the quality and naturalness level of the synthesized Chinese-flute music are apparently higher than the original HTS synthesized music.

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