Speech Prosody in Chinese Broca's and Wernicke's Aphasics: An Acoustic Investigation of Duration and Fundamental Frequency Contour

本研究旨在探討漢語失語症病人於字長及句子基頻兩方面的掌控能力，並試圖檢驗以音律(prosody)表現完好與否來區分Broca氏及Wernicke氏兩種失語症病人的有效性，以期對漢語失語症病人的音律表現有進一步認識。 我們針對六個音律特性(prosodic features)進行聲學分析。實驗結果顯示不同音律特性的損壞其彼此間是可分離的(dissociable)。此外，就病人的音律表現而言，Broca氏病人的音律並非全面性的損壞，他們仍能掌控某些音律特性的表現（如句尾基頻的下降趨勢）；而另一個方面，Wernicke氏病人未如一般預期保有完整的音律表現，其語言優勢半球的操作連帶影響了這些病人於字長與語句基頻的掌握能力。因此，若僅以音律一詞來界定，而不釐清是以音律的那些特性作比較，未免失之籠統，以致無法作出有效的失語症分類判斷。 According to clinical observations, Broca's aphasics are characterized by dysprosody, while wernicke's aphasics are regarded as having normal prosody. From the crosslinguistic viewpoint, the present study aims to examine chinese aphasics' ability in f0 programming and timing control and to assess if the prosodic dichotomy between dysprosody of Broca's aphasics and normal prosody of wernicke's aphasics is valid for aphasics of tone languages, i.e., chinese aphasics. By means of acoustic analysis, six prosodic features are investigated: sentence-final lengthening, F0 range, sentence-final peak-to-valley F0 fall, the breath-group pattern, the declination pattern, and the P1 effect. The results indicate that Broca's subjects exhibit normal tendency of sentence-final peak-to-valley F0 fall, though they have deficits in producing other prosodic features. On the other hand, wernicke's aphasics have disturbances in controlling F0 range, and producing the declination and the breath-group patterns and sentence-final lengthening, though they remain intact in producing other prosodic features. The information obtained here points out the separate disruption of prosodic features in aphasic speech and disputes the validity of differentiating Broca's from wernicke's aphasia in terms of "dysprosody" or "normal prosody". The problem with this prosodic dichotomy is that the concept about prosody is used in a too general way. It is suggested that when we use prosody as the defining symptom, we should specify which aspect of it is involved to make the classification viable