龍巖城關話是閩南西片的代表方言，語音系統與廈漳泉等閩南核心區有所不同，閩客過渡為其最大特徵。龍巖城關話的韻母系統主要呈現「聚變」（equilibrium）特徵，閩客方言在此接觸後，相異的語音系統彼此互動，逐漸形成穩定的平衡。龍巖城關話也有「裂變」（punctuation）特質，顯示出與其他閩語的深刻聯繫，只出現在舌根聲母後的-iua、-iua相當特殊，是閩語研究不可忽略的重要材料。龍巖城關話的韻母演變說明此地雖面臨閩西客語的強烈衝擊，但來自閩語內部的特點仍然牽制了語音演變的方向與方式。

Representative of the west branch of Southern-Min, the Longyan（龍巖） city dialect exhibits a phonetic system that has undergone a major transition from Southern-Min to Hakka. This phonetic evolution has contributed to a transitional status that differentiates Longyan from the core Southern-Min dialects such as those of Amoy（廈門）, Zhangzhou（漳州）, and Quanzhou（泉州）. Particularly, the rime system of the Longyan dialect shows an equilibrium gradually established through interactions and convergence between the phonetic systems of Southern-Min and Hakka. On the other hand, the Longyan dialect has undergone punctuation as well. While this mutational process evidences its lineage from proto-Min, the phonetic system of Longyan shows difference from modern Southern-Min in the distribution of the rimes -iua and -iua, which appear exclusively after velar initials. This comparison between Longyan and core Southern-Min provides important material for the reconstruction of proto-Min. Furthermore, the evolution of rime system in the Longyan dialect also illustrates that although the dialect has been faced with great assimilative pressure from Hakka, the direction and mechanisms of sound mutation is still checked by certain impervious phonetic characteristics from Min.