粵語向來被學界視為是一種見系聲母不發生顎化的漢語方言，不過在勾漏片粵語內部實際上有一群方言發生了鮮明且特殊的見系顎化音變，這種音變只發生在中古流、深、臻三攝的見系聲母，少數方言連宕攝和通攝的見系字也發生顎化，其餘中古細音字則一律不顎化。本文嘗試以比較構擬的方法找出勾漏片粵語觸發顎化音變的條件與機制，筆者發現無論從中古音還是從原始粵語出發，皆無法合理地解釋勾漏片粵語顎化的音變條件，因此筆者提出應該要從層級構擬的方法，為勾漏片粵語構擬原始勾漏片粵語。以這個系統為參照點，本文發現勾漏片粵語的顎化條件是前高介音 *i 和短元音 *ɐ，由於二者的發音時長皆很短，舌根塞音聲母受到介音 *i 和短元音 *ɐ 的過渡性質影響而弱化為塞擦音。至於部分方言只有流、深攝顎化，臻攝不顎化則是由於臻攝的前高介音較早地脫落，從而失去音變條件。

　　Yue dialects have been regarded as a group of Chinese dialects in which velar initials do not undergo palatalization. However, a subgroup of Goulou Yue dialects exhibits a unique palatalization which only occurs in the velar initials of the Liu, Shen and Zhen rhyme groups. In a small number of dialects, palatalization also occurs in the Dang and Tong rhyme groups. Yet palatalization does not occur in other syllables derived from Middle Chinese Division III and IV. This article attempts to discover the environments and conditions that cause palatalization by means of the comparative method. It argues that neither Middle Chinese nor Proto-Yue can account for the sound change. Hence, meso-reconstruction is proposed in this article to reconstruct the Proto-Goulou Yue. It suggests that medial *i and short vowel *ɐ, both of which have a short phonetic duration, should be responsible for palatalization within the reconstructed system of Proto-Goulou Yue. The absence of palatalization in the Zhen rhyme group in some dialects is due to the earlier loss of the medial *i.

勾漏片; 粵語; 顎化; 層級構擬

Goulou Yue; Yue dialects; palatalization; meso-reconstruction