本篇論文從歷史演變的角度探討閩北方言的特別聲母、聲調系統之來源。文中指出，與羅杰瑞所擬測的原始閩語"第三套" 聲母伴隨的閩北方言的調值均是較低的。這個現象不可能是周圍方言所引起的，並且也不可能是閩北方言裡層次的表現。本文的分析不但能證明羅氏的擬測是可靠的，而且能進一步確定在原始閩北時期"第三套" 塞音和塞擦音該是送氣的濁聲母。

　　　　　This paper demonstrates that Northern Min tonal splits which correlate with the "softened initials" of Norman's Proto-Min reconstruction follow a consistent pattern in terms of the pitch of the tonal contours involved. It is argued that this pitch pattern, which cannot be explained as the result of borrowing or layering, constitutes strong evidence in favor of Norman's reconstruction, while also providing grounds for specifying the phonetic nature of the "softened initials". This study references data from eight Northern Min dialects, including one described here for the first time. It is argued that a subset of these dialects forms a genetically related subgroup, for which the proto-tone system (including absolute pitch values) can be reconstructed with considerable confidence. Through additional comparison, the reconstruction of the tone system of Proto-Northern Min [PNM] as a whole is also achieved. PNM is reconstructed with eight tones and a three-way manner distinction in obstruent initials. Based on pitch patterns and universal phonetic principles, the PNM initials corresponding to Norman's Proto-Min "softened initials" are reconstructed as voiced initials with breathy release.