面對中古宕攝字，寧波方言今讀作［-ɔ̃］的語音現象，本文透過開合口、一三等的分項討論，考察出吳語太湖片方言中，寧波音具有先圓唇後高化的演變情形，其符合吳語韻母普遍具有高化的情況，卻具備更細緻的演變發展層次。歷來以寧波方言作為語音調查對象之字辭典，記音時易面臨有音無字的情形，其本字或為懸缺，故暫時尋找其他音近字作為替代。本文透過覓字法、尋音法、探義法三種研究途徑，以中古音系統作為與現代方言對照的基礎，嘗試釐清三則寧波方言本字鼻化問題。歸納出寧波方言中，有關讀作［lɔ̃6］代表稀疏義的本字，為「郎宕切」表示廣大義的「四良」字，其聲母、韻母、聲調全然符合［lɔ̃6］的語音規則對應；寧波話尚有一有音無字之「現［t'ɔ̃1］」用法，其本字當屬「他朗切」的「帑」，象徵貯存錢財之義，過往文獻亦有「現帑」的實際用法，其由官府貯藏現錢轉變為家中所藏現金義。「帑」的反切屬於透母開口一等蕩韻字，符合［t'ɔ̃1］的寧波音對應；另指稱青光眼的青［mã6］瞎，其本字乃「盲」字，少部分的梗攝開口二等字，如「盲、虻」部分語用保留［mɔ̃2］的語音現象。揭示其讀法來自兩種音韻層次，梗攝與宕攝同讀［-ɔ̃］屬於中古以前的讀法，中古以後梗攝字逐漸演變為［-ã］。

In this article, through the open-and-close-mouth method and Grade I and Grade III method in phonology, the writer will separately discuss phone phenomenon about the Ningpo dialect which is pronounced as [-ɔ̃] recently when it faced Dang She characters of middle ancient Chinese phonology. Through above discussion, the writer found out the Ningpo dialect has an evolution path from lip-rounding first to vowel raising then in northern Wu dialect. The Ningpo dialect is not only correspond to vowels of Wu dialect which commonly has a vowel-raising situation, but also has a meticulous development level. Historical dictionaries which took the Ningpo dialect as phone survey object, would easily face a problem that phonetics without word-form when noted phone. The original character may probably lose, then other characters with similar pronunciation were substituted for it temporally. This article would like to take character-searching, sound-searching, and meaning-searching as searching path, also, use middle ancient Chinese phonology to compare with recent dialects as the basement to clarify nasalization problems about three original characters in Ningpo dialect. Generalizing about Ningpo dialects, the writer will discuss three words with nasalization problem. One original character which represented "sparse" and pronounced as [lɔ̃6], or "四良" character which represented "vast" and pronounced as "lang" for the "l" sound combined with "tang" for the "ang" sound, initials, vowels, and tones of these words are corresponded with the phono rule of [lɔ̃6]. Another character which with phonetic and no word-form is pronounced as [t'ɔ̃1], its original character is "帑\" and pronounced as "ta" for the "t" sound combined with "lang" for the "ang" sound. The meaning of this word is to store money up. Historical literatures also have the actual use of this word, and the meaning of this word had changed from explain the government store up money to money stored up in the house. The fan-chieh of "帑\" belongs to "tou" initial and "dang" vowel with open mouth of Grade I, is corresponded with the Ningpo sound [t'ɔ̃1]. The other character "青□瞎\" which represented blind in glaucoma is pronounced as [mã6], its original character is "盲\". Some Grade II words like "盲\" and "虻\" in Gang She with open mouth have preserved the [mɔ̃2] phone phenomenon. By revealing the source about the pronunciation of this word, there might be two phonology level can be the explanation. Before the middle ancient of Chinese phonology, the pronunciation of Gang She were common with Dang She which pronounced as [-ɔ̃], and after the middle ancient, the pronunciation of Gang She gradually advanced to [-ã] sound.