Nasal coarticulation and sound-change: a real-time MRI study

语音产生高度依赖于语境，因为语音的声音在时间上重叠并相互影响。对于元音后面跟着鼻辅音的声音序列也是如此：在流利的语音中，与鼻塞相关的降膜手势在元音期间启动，即在实现鼻塞的口头收缩之前。因此，在许多语言中，元音在鼻音之前的鼻化程度通常高于口语辅音之前的鼻化程度。在一些语言中，如法语，这种类型的语音变化在历史上演变为元音的鼻口对比，并删除了后面的鼻辅音。解释鼻化音系化的根本是理解鼻辅音的两个主要发音机构--膜和鼻辅音的口腔收缩--是如何彼此分离的，例如法语Main(‘Hand’)/mɛ̃/来自拉丁语Manus，其中/n/的牙槽接触最初被借出，然后随着鼻化在元音中的增加而消失。这个项目的总体目的是确定可能导致鼻化越来越多地与鼻音上下文中的元音联系在一起的语音条件。在前述提议的丰硕成果的基础上，该项目将更具体地关注当语音条件改变时舌头和舌膜的手势间重组，特别是如果由于不同的语音模式(阅读语音与自发语音)或由于控制语速(中速语音与快速语音)而导致语音片段和单词持续时间缩短的情况。分析将主要集中在包含发声后鼻音的高频虚词，其中缩写的可能性比不太频繁的实词更大。实时核磁共振将被用来记录多达60名说标准德语的人，以跟踪膜相对于其他关节的运动，特别是舌尖。德语适合于这样的研究，这既是因为在涉及鼻音的过程中没有已知的声音变化，也因为鼻音出现在如此广泛的不同环境中。在数据采集方面，将使用80fps(12.5ms)的高时间分辨率，这对于捕捉舌尖微小、快速运动的细节特别有利，这些细节的分析构成了更新建议的关键部分。为了分析随时间变化的语音数据的声音变化，更新建议将利用函数主成分分析(FPCA)，这是一种将信号的随时间变化的形状表示为一组主成分的方法，这些主成分是时变函数。这个项目将有助于更深入地理解不同的说话风格、声音语境和词频如何影响语膜和舌尖的手势间重组，以及这种变化如何为声音变化提供条件。

Speech production is highly context-dependent because the sounds of speech overlap and influence each other in time. This is also true for sound sequences in which a vowel is followed by a nasal consonant in fluent speech: the velum lowering gesture that is associated with the nasal stop is initiated during the vowel, i.e. before the oral constriction for the nasal stop is achieved. Thus, in many languages, vowels are typically more nasalised before nasal than before oral consonants. In some languages like French, this type of phonetic variation has evolved historically into a nasal-oral contrast in the vowel combined with a deletion of the following nasal consonant. Fundamental to explaining the phonologisation of nasalisation is an understanding of how a nasal consonant's two primary articulators – the velum and the nasal consonant's oral constriction – become disassociated from each other, as in e.g. French main (‘hand’) /mɛ̃/ from Latin manus, in which the alveolar contact for the /n/ presumably initially lenited and was then lost as nasalisation in the vowel increased. The overall purpose of this project is to determine the phonetic conditions that could cause nasalisation to become increasingly associated with an oral vowel in a nasal context. Building on the fruitful results of the preceding proposal, this project will focus more specifically on the inter-gestural reorganisation of the tongue and the velum when phonetic conditions are modified, especially if the segment and word duration is decreased during speech due to different speech modes (read speech vs. spontaneous speech) or due to controlled speech rates (moderate vs. fast speech). The analysis will primarily focus on highly frequent function words containing post-vocalic nasals in which reduction is more likely than in less frequent content words. Real-time MRI will be used for recording up to 60 speakers of Standard German to track the movement of the velum in relation to other articulators, in particular the tongue tip. German is appropriate for such a study both because there are no known sound changes in progress involving nasals and because nasals occur in such a wide range of different contexts. For data acquisition, a high temporal resolution of 80 fps (12.5 ms) will be used, which is particularly advantageous for capturing details of small, fast tongue-tip movements whose analysis forms a key part of the renewal proposal. For the purposes of analysing sound change from time-varying speech data, the renewal proposal will make use of functional principal component analysis (FPCA), a method that expresses time-varying shapes of signals as a set of principal components which are time-varying functions. This project will lead to a deeper understanding of how the inter-gestural reorganisation of the velum and the tongue tip is affected by different speaking styles, sound contexts and word frequency, and how such variation provides the conditions for sound change.