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Electropalatographic study of voicing assimilation in Czech alveolar plosives
Vaněčková, Kateřina ; Skarnitzl, Radek (advisor) ; Machač, Pavel (referee)
The phonological contrast of voicing is based on several phonetic differences which are yet to be satisfactorily explained. The most obvious of them is the presence of vocal cords vibration which has so far been considered crucial in Czech. For capturing the differences in other dimensions, the concept of the strength of articulation, or fortis/lenis contrast have been established. There are some rare cases in languages when the couple of phonemes with the voicing contrast differs also in another feature that cannot be explained by the fortis/lenis dimension correlates. This is the case of Czech alveolar plosives which have been described to differ in their place of articulation: the linguopalatal contact is more anterior for [t] that for [d]. The main aim of this study is to ascertain whether this contrast can indicate the original phoneme in the contexts where the voicing contrast is neutralized due to assimilation. Nevertheless, our electropalatographic data from 7 speakers of Czech show that not only the phonemes do not seem to influence the anteriority of the voicing realisation, but also the very asymmetry of linguopalatal contact in the voicing realisations tends to be neutralised in the segmental context used in our study, that is in coda position in the word-final syllable followed by the...
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Assimilation of voicing in Slovak speakers of English
Ortutayová, Dominika ; Skarnitzl, Radek (advisor) ; Popelíková, Jiřina (referee)
The aim of this thesis is to examine the influence of the mother tongue, more specifically Slovak, in the speech of the Slovak speakers of English and subsequent appearance of the assimilation of voicing in the environments in which it is expected in both Slovak and English and then in those which are typical only for Slovak - and the production of the assimilation of voicing in those environments in English is considered an error. In the first part we introduce and specify the process of voicing in speech in general and then in the second part we proceed with the presentation of the concept of the second language acquisition and language interference. The empirical part is based on the analysis of the material spoken by 18 students, both males and females, reading the BBC bulletins. Our results show that the assimilation of voicing is an integral part of the speech of Slovaks in English, proving that they assimilate extensively in the environments typical for the Slovak language. Those are only partially typical for English as well - and thus they simultaneously produce assimilation errors. This knowledge could be taken in account during the learning process in order to eliminate such errors as much as possible. Key words: voicing, assimilation, Slovak, English, interference
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Synthesis of the voicing characteristics of Czech plosives and their preliminary perceptual verification
Urban, Kristian ; Skarnitzl, Radek (advisor) ; Studenovský, David (referee)
This paper will discuss voicing characteristics of Czech plosives. In the theoretical part of the paper, vocal cords are described as well as their participation on voicing. Next, a brief history, division, and application of voice synthesisers is discussed. Synthesizers allow the user to manipulate individual characteristics of any speech signal. In the practical part of the paper, HLsyn is used to synthesize individual Czech plosives with various voicing characteristics. Perceived voicing is then evaluated based on preliminary perceptual verification. Keywords: voicing, plosives, synthesis, HLsyn, perception test
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Relationship between the strength of Czech accent and the duration of vowels before obstruents
Fejlová, Dita ; Skarnitzl, Radek (advisor) ; Tichý, Ondřej (referee)
This bachelor thesis aims to inspect the presence or absence of a feature called pre- fortis shortening in English spoken by Czechs. The term denotes the shortening of a vowel preceding a voiceless obstruent. This feature is known to appear in various languages like Russian, French, Italian; indeed, Matthew Chen even suggests it is language-universal. In English the feature is very prominent and because it affects speech perception, it is even considered a primary indicator of the voicing of the following obstruent. A study included in this thesis examines the extent to which 12 female speakers of Czech English, sorted into 3 categories according to their proficiency in pronunciation, mark the distinction between words like "bet" and "bed" by vowel shortening. The study does not exploit minimal pairs like these, but vowel-obstruent sequences taken from long read passages of BBC news. The the fortis/lenis character of the final obstruent contained in these sequences is a discerning parameter which always separates the data into two groups, the vowel durations of which are then compared. Statistical analysis of the data showed that contrary to the expectations, speakers with native-like pronunciation were not the ones who displayed the most massive usage of pre-fortis shortening. Possible reasons for...
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Switching off of Electrical Tools by Voice
Rozsypálek, Lukáš ; Šebesta, Vladimír (referee) ; Sigmund, Milan (advisor)
In theoretical part Master’s thesis deals with processing acoustic signal before speech recognition. There are described methods of automatic speech recognition and capture attributes. Those methods are short-term energy of signal, short-term autocorrelation analysis, linear predictive analysis etc. In practical part has been created software, which has to switch off of electrical tool, if the keyword “zastav” has been spoken. In the second part of this thesis software has been optimized for work in real conditions (noise generated by electrical tools).
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Speech denoising based on wavelet transform and voice recognition in segments
Chrápek, Tomáš ; Sysel, Petr (referee) ; Rajmic, Pavel (advisor)
The wavelet transform is a modern signal processing tool. The wavelet transform earned itself a great success mainly for its unique properties, such as the capability of recognizing very fast changes in processed signal. The theoretical part of this work is introduction to wavelet theory, more specifically wavelet types, a wavelet transform and its application in systems dealing with signal denoising. A main problem connected to speech signals denoising was introduced. The problem is degradation of the speech signal when denoising unvoiced parts. It is because of the fact that unvoiced parts and noise itself have very similar characteristics. The solution would be to apply different attitude to voiced and unvoiced segments of the speech. The main goal of this diploma thesis was to create an application implementing the speech signal denoising using the wavelet transform. The special attention should have been paid to applying different attitude to voiced and unvoiced segments of the speech. The demanded application is programmed as a grafical user interface (GUI) in MATLAB environment. The algorithm implemented in this form allows users to test introduced procedures with a great comfort. This work presents achieved results and discusses them considering general requirements posed on an application of given type. The most important conlusion of this Diploma Thesis is the fact that some kind of trade-off between sufficient signal denoising and keeping the speech understandable has to be made.
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