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Effect of background population on Bayesian conclusions in speaker comparison
Štrosová, Veronika ; Skarnitzl, Radek (advisor) ; Bořil, Tomáš (referee)
Salient goal of forensic phonetics is evaluation of evidence. For this purpose, this field widely uses the Bayesian approach to evidence evaluation, specifically the likelihood ratio (LR). In this probabilistic method of evidence evaluation, which works with concepts of similarity and probability, is background population one of its main cornerstones. This thesis focuses on the effect of background population on the performance of LR based forensic speaker comparison. The LR based classification used midpoint formant values F1, F2 and F3 from Czech vowels of male native speakers. Using Lindleys (1977) parametric LR approach, these acoustic parameters were used to observe the effect of background population varying from 1 to 30 speakers on the validity and reliability of the classification. The analysis showed effect of background population on system performance, whereby the LR output had the lowest validity and reliability using small sample sizes of reference speakers. Simultaneously, the analysis showed an onset of stabilization of the system performance from the perspective of validity as well as reliability from a threshold of background population of 10 reference speakers. In particular cases was also observed synonymous classification validity using very low reference samples with...
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Acoustic parameters of the speech signal and their intra- and interindividual variability in Czech
Houzar, Alžběta ; Skarnitzl, Radek (advisor) ; Volín, Jan (referee) ; Hes Svobodová, Marie (referee)
The doctoral thesis focuses on the variability of a wide range of acoustic parameters of the speech signal in the Czech language. It summarizes the methodological approaches applied in previous studies on the acoustic characteristics of speech and presents a comprehensive analysis of intra-speaker and inter-speaker variability of an extensive set of selected parameters through original experiments conducted using a unified speech material. The individual experiments examined acoustic parameters that characterize fundamental frequency, vowel formants, short- and long-term frequency spectrum, and the temporal domain of speech, employing a total of 61 metrics. The variability of all parameters was observed within an individual's speech during one type of utterance as well as in relation to speaking style, with recordings of both read and spontaneous speech from thirty speakers being analyzed. Based on the experimental results, information regarding the distribution of parameter values in both speaking styles within the given population was obtained. In the final experiment, a comprehensive analysis of all investigated parameters was conducted, focusing on their mutual relationships and their contribution to the overall variability of the speech signal. The results of this comprehensive analysis...
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Fundamental frequency behaviour in Czech sonorous syllabic codas
Svatošová, Michaela ; Volín, Jan (advisor) ; Skarnitzl, Radek (referee)
It has been established that listeners perceive intonation only in certain parts of the fundamental frequency (F0) contour. Descriptions of melodic patterns are often based on F0 values in vowels. However, pitch can be controlled also in sonorants (nasals, approximants), which can be part of syllabic codas in Czech. The aim of this thesis was to compare syllables with a sonorous coda and without a coda, and to examine whether the F0 contours are more similar in the domain of the syllabic nucleus or rather in the domain of the syllabic rime. The material consisted of a two-hour collection of audiobook samples recorded by sixteen professional actors. The analysis used multiple methods - representing F0 con- tours by selected discrete points, modelling the whole F0 contour with Legendre polynomials, and functional principal component analysis (FPCA). The results indicated that the syllabic rime represents the domain relevant for the production of functional melodic patterns (melodemes) in Czech. F0 contours in syllabic rimes showed more similar values of span (across both types of sylla- bles) than F0 contours measured in syllabic nuclei. Their shapes were also more comparable when syllabic rimes were considered. In syllables with a sonorous coda, the relationship between the slope of the F0 contour...
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Effect of pitch manipulation on the evaluation of credibility in political candidates
Bartošová, Jana ; Šturm, Pavel (advisor) ; Skarnitzl, Radek (referee)
This MA thesis is dealing with the relationship between the pitch of the fundamental frequency of the speaker's voice and the subjective evaluation of the speaker by listeners on a 7point rating scale. The analysis in this thesis was conducted in the form of a perception test in which 39 listeners participated. Participants in the experiment rated the speaker based on how credible the speaker sounded to them. The material was chosen such that the listeners were influenced as little as possible by any possible external influences. The results of the perception test showed a correlation between the type of manipulation and the listeners' evaluations. The hypothesis of the paper was partially confirmed because listeners decreased their average evaluation the higher the f0 value of the item and this relationship was statistically significant. It was also shown that the lower the f0 value of the item, the more credibility evaluations tended to increase, but this change did not prove to be statistically significant. Key words: Fundamental frequency, f0, credibility perception, pitch, perception, voting
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In-class pronunciation of Czech teachers of English and their cognition about pronunciation
Čtvrtečková, Lenka ; Skarnitzl, Radek (advisor) ; Veroňková, Jitka (referee)
The thesis deals with teacher cognition in the pronunciation teaching of Czech secondary school English teachers, presents their actual pronunciation based on authentic recordings of classroom lessons and searches for intersections between the two domains in the context of current research on pronunciation teaching and Czech English. The theoretical part of the thesis introduces the topic of pronunciation teaching and defines its goals in accordance with current research that prioritizes intelligibility, introduces the concept of teacher cognition, and summarizes what is yet known about the sound properties of Czech English. The practical part includes the assessment of teacher cognition data collected from Czech teachers from secondary schools through questionnaires and the material in the form of authentic recordings from lessons at schools. The recordings are subsequently analysed auditorily in terms of selected segmental and suprasegmental pronunciation phenomena; this part also includes a search for any intersections of these two areas. A total of 11 respondents participated in the study, however, only 10 recordings were suitable for analysis. The data show that pronunciation teaching is important for teachers and one of their goals is the intelligibility of students for others. However, few believe in...
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Forensic potential of temporal structure metrics in Czech spoken texts
Jalová, Marie Zoe ; Volín, Jan (advisor) ; Skarnitzl, Radek (referee)
This thesis focuses on temporal structure metrics in a speech. The theoretical part describes their character and their possibility in forensic use, the practical part examines, based on two recordings of poetry, the behavior of temporal structure metrics in a relation to the material and the identity of a speaker. This thesis makes a contribution to the description of temporal structure of the czech language, specifically to the poetry genre, with a potential use in forensic phonetics.
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Melodic contours in political debates: comparison of British and American English
Vonzová, Veronika ; Skarnitzl, Radek (advisor) ; Luef, Eva Maria (referee)
The thesis focuses on the differences between British and American English in terms of their phrasal characteristics (length of phrases, nuclear pitch movement, pitch range). By doing so, it aims to fill a gap in research which lies in a lack of comparative studies of the two mentioned varieties of English on the suprasegmental level. The theoretical part describes prosody and its functions in language, intonation, and individual types of nuclear pitch movements and their functions. The paper further concentrates on the differences between the British and American schools of intonation notation and also the differences and discrepancies between their terminologies. Finally, it introduces a new term inspired by Czech terminology, FMU, which is not present in English terminology and helps to differentiate between the form and function of the nuclear pitch movements. FMU corresponds to the scope of the Czech term "melodém" (the function of the pitch movement, e.g., the falling FMU), as opposed to the realization (Czech "kadence", the concrete realization of the FMU, e.g., the level-fall). The empirical part presents a study carried out on a sample of 800 phrases (400 British and 400 American), which are compared in the following areas: the length of phrases, type of the nuclear pitch movement, and...
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Rotacism in Czech and its perceptual response
Šimková, Iva ; Černá, Martina (advisor) ; Skarnitzl, Radek (referee)
This bachelor thesis aims to contribute to the research of the relation between the speech of speakers with rhotacism and negative evaluation in the perception of their speech. A perception test was created based on the previous research concerned with the perception of disrupted speech and more detailed characteristics of rhotacism. The test was based on samples of utterances that were selected from the speech of five speakers with rhotacism. The test provided the necessary material for data analysis through indirect testing of the perceptive response of thirty-six respondents. The analysis deals with the comparison of the utterances which contained the problematic /r/ sound to the utterances which were missing the problematic /r/ sound as a result of the perceptive score. Based on the descriptive and frequentist statistics, it has been found that the utterances with rhotacism were evaluated more negatively than the utterances without the vibrant /r/. The thesis also attempts to expose the possible relations between the implemented type of rhotacism or the context in which the sound /r/ occurs, and the perceptive response of these phenomena.
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Effect of speech rhythm manipulations on speakers' credibility
Rabanová, Michaela ; Skarnitzl, Radek (advisor) ; Cilibrasi, Luca (referee)
This thesis aims to determine whether irregular rhythm of speech in English native speakers has an effect on how trustworthy they sound to listeners. Next, it aimed to determine whether university students of the English language evaluate the trustworthiness of speakers with irregular rhythm differently than non-English students. The thesis is divided into theoretical and practical parts. The theoretical part describes general observations about rhythm of speech, ways of evaluating one's personality, and certain speech characteristics which contribute to sounding less trustworthy. The practical part describes the methodology that was used to answer the research questions. For this purpose, an experiment where the natural rhythm of English speakers underwent artificial manipulation was conducted. These manipulated recordings were then combined with unchanged recordings from the same speakers. The level of trustworthiness of all the speakers in both manipulated and unchanged recordings was then evaluated in an online perception test by English students and non-English students. The collected data prove that speakers whose rhythm was manipulated are seen as less credible than those whose rhythm remained unchanged. When it comes to the difference between English students and non-English students, it...
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Canonical and actual speech and articulation rate throughout spoken dialogues
Línková, Alena ; Skarnitzl, Radek (advisor) ; Volín, Jan (referee)
Speech tempo and its variability in Czech have been the subject of many studies, but most of them have primarily focused on monologues. In this bachelor thesis, we focus on speech tempo variability in dialogues, as well as on different ways of measuring speech tempo and how that can affect the values obtained. The thesis includes a theoretical section that summarizes current knowledge regarding speech tempo, different ways of objectively measuring it and factors affecting its values, perception of speech tempo and factors that affect it, pauses, and the specifics of speech tempo in dialogues. In the practical section, we analysed the recordings of 13 speakers participating in a television political debate. We measured articulation rate in prosodic phrases and speech rate in clauses and thematically unified paragraphs, as well as local rate in the initial, medial, and final thirds of these dimensions. We measured syllable (syll/s) and phone rate (ph/s), and canonical and surface (syllable) rate. We found statistically significant differences between tempo values in thirds of clauses (syll/s) and prosodic phrases (ph/s), but not in paragraphs (syll/s). The effect of the length of a prosodic phrase on both syllable and phone rate values was, however, found not to be statistically significant. Powered by TCPDF...
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