Word-level pronunciation reduction in spotaneous speech and identification of speech units

The thesis deals with the issue of word-level pronunciation reductions and with the identification of reduced word forms. The first part of the thesis focuses on the degree of the phonetic features' stability and presents an analysis of selected words from dialogues with a high degree of spontaneity. The results of this research confirm that the most stable features of speech are the fricativness of sibilants and / /ř , voice, the formant structure of vowels and the nasality of the nasal consonant. The closure of the explosives and the quality of vowels prove, on the other hand, to be relatively unstable features. The second part of the thesis focuses on perceptual tests, which are used to verify the identifiability of the selected words in relation to the degree of reduction and the type and complexity of the context. Furthemore, the thesis tries to determine the phonetic features, which are under given conditions relevant for the appropriate identification of words. The research proved, that the most often noted phonetic features correspond to the above mentioned features with high stability. Moreover, it was also confirmed, that the recognizability of words depends on the degree of their reduction and the type of the context: strongly reduced words without any context tend to be very difficult..