Mechanisms of vowel devoicing in Japanese

The processes of vowel devoicing in Standard Japanese were examined with respect to the phonetic and phonological environments and the syllable structure of Japanese, in comparison with vowel reduction processes in other languages, in most of which vowel reduction occurs optionally in fast or casual speech. This thesis examined whether Japanese vowel devoicing was a phonetic phenomenon caused by glottal assimilation between a high vowel and its adjacent voiceless consonants, or it was a more phonologically controlled compulsory process. Experimental results showed that Japanese high vowel devoicing must be analysed separately in two devoicing conditions, namely single and consecutive devoicing environments. Devoicing was almost compulsory regardless of the presence of proposed blocking factors such as type of preceding consonant, accentuation, position in an utterance, as long as there was no devoiceable vowel in adjacent morae (single devoicing condition). However, under consecutive devoicing conditions, blocking factors became effective and prevented some devoiceable vowels from becoming voiceless. The effect of speaking rate was also generally minimal in the single devoicing condition, but in the consecutive devoicing condition, the vowels were devoiced more at faster tempi than slower tempi, which created many examples of consecutively devoiced vowels over two morae. Durational observations found that vowel devoicing involves not only phonatory change, but also slight durational reduction. However, the shorter duration of devoiced syllables were adjusted at the word level, so that the whole duration of a word with devoiced vowels remained similar to the word without devoiced vowels, regardless of the number of devoiced vowels in the word. It must be noted that there was no clear-cut distinction between voiced and devoiced vowels, and the phonetic realisation of a devoiced vowel could vary from fully voiced to completely voiceless. A high vowel may be voiced in a typical devoicing environment, but its intensity is significantly weaker than those of vowels in a non-devoicing environment, at all speaking tempi. The mean differences of vowel intensities between these environments were generally higher at faster tempi. The results implied that even when the vowel was voiced, its production process moved in favour of devoicing. However, in consecutive devoicing conditions, this process did not always apply. When some of the devoiceable vowels were devoiced in the consecutive devoicing environment, the intensities of devoiceable vowels were not significantly lower than those of other vowels. The results of intensity measurements of voiced vowels in the devoicing and nondevoicing environments suggested that Japanese vowel devoicing was part of the overall process of complex vowel weakening, and that a completely devoiced vowel was the final state of the weakening process. Japanese vowel devoicing is primarily a process of glottal assimilation, but the results in the consecutive devoicing condition showed that this process was constrained by Japanese syllable structure

Character Recognition

Character recognition is one of the pattern recognition technologies that are most widely used in practical applications. This book presents recent advances that are relevant to character recognition, from technical topics such as image processing, feature extraction or classification, to new applications including human-computer interfaces. The goal of this book is to provide a reference source for academic research and for professionals working in the character recognition field