The existence of incomplete neutralisation in connection with processes like final devoicing is well-known, but little work exists on typologically more uncommon morphological processes such as Celtic initial mutation. This paper reviews the small existing literature on incomplete neutralisation in initial mutation, showing that no convincing evidence has been found so far, and presents a new nasal airflow study on four speakers of Scottish Gaelic that adds to these negative results.

Radical initial /p/ and /m/ in Scottish Gaelic are neutralised to [v] under the lenition mutation. Vowels following radical initial /m/ in Scottish Gaelic may display either categorical phonological nasalisation or gradient phonetic nasalisation. Nasal airflow in items with radical initial /p/ and /m/ is measured in order to determine whether the degree of vowel nasalisation after [v] in lenited forms is sensitive to the identity of the corresponding radical consonant. LME model comparison finds that only categorical phonological nasalisation, and not gradient phonetic nasalisation, may be subject to morphological conditioning. This is at odds with widespread existing findings for processes such as final devoicing, where the gradient phonetic properties of neutralised segments display sensitivity to paradigmatic effects.

The absence of incomplete neutralisation in initial mutation is consistent with recent proposals that restrict the types of morphophonological processes that may bring about incomplete neutralisation to highly transparent, phonetically natural processes involving conflict between word-specific morphological pressures and language-wide phonotactic constraints. These findings can inform us about the structure of the mental lexicon and the derivation of morphologically complex forms.

与最终清音等过程相关的不完全中和的存在是众所周知的，但是在类型上更不常见的形态学过程（例如凯尔特人初始突变）方面几乎没有工作。本文回顾了有关突变中不完全中和的现有文献，表明迄今为止还没有令人信服的证据，并且对苏格兰盖尔语的四位演讲者进行了一次新的鼻气流研究，进一步增加了这些负面结果。

在lenition突变下，苏格兰盖尔语中的自由基初始/ p /和/ m /被中和为[v]。苏格兰盖尔语中部首首字母/ m /之后的元音可能会显示类别的语音鼻音化或梯度语音鼻音化。测量基本首字母为/ p /和/ m /的项中的鼻气流，以确定[v]后以编织形式的元音鼻音化程度是否对相应的基本辅音的身份敏感。LME模型比较发现，只有分类语音鼻腔化，而不是梯度语音鼻腔化，可能会受到形态学条件的影响。这与诸如最终清音的过程中广泛存在的发现相矛盾，在该过程中，中和部分的梯度语音特性显示出对范式效应的敏感性。

初始突变中不完全中和的缺乏与最近的提议相一致，该提议将可能导致不完全中和的形态学过程类型限制为高度透明的，语音上自然的过程，其中涉及特定单词的形态压力与全语言的音位约束之间的冲突。这些发现可以告诉我们有关心理词典的结构以及形态复杂形式的推导。