聲學分析（acoustic analysis）是對於語音做客觀的描述工具，也可進一步推論語音的製造 歷程。本研究使用語音聲學分析調查國語捲舌和非捲舌摩擦音與塞擦音的特性，包括噪音頻譜 特徵和噪音時長。首度使用頻譜動差的方法分析國語的摩擦音與塞擦音無聲噪音音段的FFT量 能頻譜，計算四個頻譜動差參數(平均數M1、變異數M2、偏態M3、峰度M4)後，比較四個動差 參數和噪音時長在捲舌音和非捲舌音的對比情形。本研究包括兩個實驗。在實驗一中使用的語 音材料包括有國語雙音節詞語和對話問答題，分析三十位男女說話者在雙音節詞語中捲舌和非 捲舌摩擦音與塞擦音的噪音音段頻譜特性，包括時長測量和四個頻譜動差參數分析。對於噪音 音段動差分析的結果顯示捲舌音與非捲舌音之間在四個動差參數中皆有顯著差異。和非捲舌音 相較，捲舌音具有較小的M1和 M4以及較大的M2和M3。捲舌音的噪音音段較非捲舌音稍短， 且女性的捲舌音對比特徵較男性的明顯。實驗二比較在構音上捲舌動作的強弱對頻譜動差參數 的影響，在實驗二中訓練受試者說出不同捲舌程度的捲舌音，共有二十位女性參與實驗，包括 完全不捲舌，有四種程度的捲舌程度變化，分析四個動差參數，得到由不捲舌、稍捲舌、中捲 舌到最捲舌的動差參數變化趨勢。其中M1有隨著捲舌程度的增加漸漸降低的趨勢，M2、M3則 是隨著捲舌程度的增加漸漸增加，M4變化的趨勢較為非線性。四個參數中顯示M1對於捲舌音 舌位的變化較為敏感，也是有效區分捲舌音和非捲舌音的聲學指標。 綜合實驗一和實驗二捲舌音對比和不同捲舌程度語音的聲學分析結果可知捲舌音的頻譜重 心頻率較低，能量分佈較散，峰態較平坦，藉由這些捲舌音對比的動差參數的差異，可進一步 推論國語捲舌音的構音特性。

The major acoustic characteristics of fricatives and affricates are the high frequency frication noise, usually shown as strong aperiodic noise energy on a spectrograph. A statistical approach for the power spectrum, spectral moment analysis was used to analyze the noise power spectrum of fricatives and affricates noise of Taiwan Mandarin. Four parameters in spectral moment analysis are M1(mean),M2 (variance),M3 (skewness) and M4 (kurtosis), derived from crosssectional FFT power spectra, which can be interpreted as central gravity, energy dispersion, spectral tilt and peakedness of spectrum, respectively. The purpose of this study was to compare moment parameters of the retroflexed and nonretroflexed fricatives and affricates of Mandarin, and investigate the four moment parameters in distinguishing the retroflexion contrast in Taiwan Mandarin. The experiment I investigated the four spectral moment characteristics for retrof lexion contrast distinction in disyllabic words. The spectral moments and the noise duration of fricatives and affricates were measured for 30 adults (15 males and 15 females). The speech was sampling in two situations, one is in quiz activity, and the other in disyllabic word reading. Result was shown that there was significant difference between in four spectral moments and noise duration between the retroflexed and the nonretroflexed. Compared to the nonretroflexes, the retroflexed fricatives and affricates have lower M1 and M4, and greater M2 and M3. In the oral quiz situation, the answered words of speakers were less retrof lexed than those in the reading situation. In the experiment II, 20 female speakers varied the retrof lexed posture in fricative and affricate production. There were four degrees of articulatory retroflextion: nonretroflexed, mild retroflexed, moderate retrof lexed and the most retrof lexed. The result was shown that the tendency of retroflextion influenced the four spectral moments systematically. The linkage between spectral moments and tongue positions and the relationship among the spectral moments and production of the retroflexation contrast in Mandarin were discussed, as well as the phonetic contextual effects on the noise gravity frequency of nonretroflexed fricatives and affricates.