Dissertations / Theses on the topic 'Speech forensics'

Forensics, or competitive speech and debate, has a history stretching back to the ancient Greeks. Although practitioners, students, and coaches have long sung its praises, limited research has been done to demonstrate the long-term value of forensics competition for students. This study used narrative interviews to discover the perceived value of forensics competition to individuals who were at least ten years removed from competition and had not remained active in forensics. After interviewing 34 individuals, this study used grounded theory (Glaser, 1965; 2002; Glaser & Strauss, 1967) to analyze the results. Analysis revealed that individuals followed a similar pattern of becoming involved in forensics and remaining as participants. Additionally, they believed they learned academic skills, social skills, and had more opportunities because of their participation in forensics, despite having to overcome some negative effects of participation. Participants noted that they used many of the skills they developed in forensics every day. Participants also demonstrated that forensics was a part of their identity and many remained connected to former teammates, former competitors, and their alma mater. Analysis led to the development of the Narrative of the Professional, which is the story of the forensics competitor.

Forensic audio recordings are usually made with a single covert microphone in non-ideal conditions. In non-ideal conditions the recordings are highly susceptible to various types of noise. The noise is usually broadband noise, co-talker interference, impulsive noise, narrow band noise or convolutional noise. There are existing speech enhancement techniques available to suppress most of the noise types mentioned, but when the noise is of a considerable level the performance of most enhancement techniques tend to decrease significantly. This thesis presents a study of speech enhancement techniques that are applicable to the enhancement of forensic audio recordings or that can be used in a forensic recording environment. It considers both pre-processing and post-processing speech enhancement techniques. This thesis investigates the improvement of some of the existing speech enhancement techniques as well as proposing some new ones. The performance of the improved and proposed speech enhancement techniques were evaluated objectively using the segmental signal-to-noise ratio (SNRseg) and subjectively using the mean opinion score (MOS). A review of the current speech enhancement techniques is presented in the thesis and is also used as a reference in some comparisons. The current speech enhancement techniques considered are those that are applicable to forensic audio recordings. The performance of the existing techniques are assessed in the comparisons with the speech enhancement techniques proposed by this thesis. Two pre-processing speech enhancement techniques are presented in this thesis. The first pre-processing speech enhancement technique is designed to improve existing broadband noise suppression techniques by the use of frequency shift keying (FSK) signals. It is based on a simple concept, which is to insert a known tone of sufficient amplitude into the silent segments of a speech signal prior to transmission. At the receiver the detection of silent or non-speech segments used in estimating the noise, becomes a simpler and more accurate task due to the inserted tone. The second pre-processing speech enhancement technique is designed to suppress a wide range of noises and it is based on zero padding. Zero padding involves inserting a zero value sample in between each speech signal sample prior to transmission. The inserted zero value samples allow accurate characterisation of the noise in the adjacent speech samples. At the receiver the noise is estimated from the sample positions allocated for the zero value samples. Several post-processing speech enhancement techniques are presented in this thesis. The first post-processing speech enhancement technique is designed for the suppression of co-talker interference and it uses a combination of dynamic time warping (DTW) and dual channel adaptive filtering. This technique is proposed for the suppression of co-talker interference, when the co-talker interference or noise reference signal is obtainable at a later instance as in the case of many covert forensic recordings. The corrupted speech signal and the noise reference signal are aligned using DTW and then the co-talker interference is suppressed using a dual channel adaptive filter. The second post-processing speech enhancement technique is designed for broadband noise suppression and is based on spectral subtraction but it incorporates the masking properties of the human auditory system for improved performance. Auditory masking is used to find the masking threshold, below which the noise is no longer perceivable. Only those noise components above the masking threshold are suppressed. This approach is taken to reduce any byproducts such as musical noise. The third post-processing speech enhancement technique is designed for broadband noise suppression and is based on spectral subtraction but it exploits the human auditory systems perception of frequency. Critical band analysis is used to group frequencies that are similarly perceived, which are then treated as a single entity by the enhancement technique.

This thesis examines speech processing systems appropriate for use in forensic analysis. The need for automatic speech processing systems for forensic use is justified by the increasing use of electronically recorded speech for communication. An automatic speaker identification and verification system is described which was tested on data gathered by the Queensland Police Force. Speaker identification using Gaussian mixture models (GMMs) is shown to be useful as an indicator of identity, but not sufficiently accurate to be used as the sole means of identification. It is shown that training GMMs on speech of one language and testing on speech of another language introduces significant bias into the results, which is unpredictable in its effects. This has implications for the performance of the system on subjects attempting to disguise their voices. Automatic gender identification systems are shown to be highly accurate, attaining 98% accuracy, even with very simple classifiers, and when tested on speech degraded by coding or reverberation. These gender gates are useful as initial classifiers in a larger speaker classification system and may even find independent use in a forensic environment. A dual microphone method of improving the performance of speaker identification systems in noisy environments is described. The method gives a significant improvement in log-likelihood scores when its output is used as input to a GMM. This implies that speaker identification tests may be improved in accuracy. A method of automatically assessing the quality of transmitted speech segments using a classification scheme is described. By classifying the difference between cepstral parameters describing the original speech and the transmitted speech, an estimate of the speech quality is obtained.

Law enforcement agencies often engage in surveillance operations which involve the recording of spoken conversations. As is often the case, these recordings are made with a single microphone under covert conditions. Under this non-ideal situation, the speech signal is highly susceptible to be severely corrupted by various forms of noise, the most common of which is broadband in nature. This thesis presents a study conducted to investigate the enhancement of speech recordings for forensic applications. A new speech enhancement scheme has been proposed here, to provide noise reduction without compromising the intelligibility of the speech. The scheme implements a hybrid approach combining both spectral and root-cepstral subtraction. Extensive testing using both subjective and objective based intelligibility and acceptability assessment schemes, indicate that the system is successful in providing intelligibility improvement and superior signal-to-noise ratio with minimal spectral distortion. In addition, the proposed system was also tested in the capacity as a preprocessing stage to other speech applications such as speech recognition, speaker recognition and speech coding. The system proved to be beneficial for speech coding, while application to the recognition techniques was limited despite showing positive potential. Finally the system was implemented in real-time and was found additionally successful when applied to enhancement of speech transmitted over High Frequency communication channels.

A major application of Speaker Identification (SI) is suspect identification by voice. This thesis investigates techniques that can be used to improve SI technology as applied to suspect identification. Speech Coding techniques have become integrated into many of our modern voice communications systems. This prompts the question - how are automatic speaker identification systems and modern forensic identification techniques affected by the introduction of digitally coded speech channels? Presented in this thesis are three separate studies investigating the effects of speech coding and compression on current speaker recognition techniques. A relatively new Spectral Analysis technique - Higher Order Spectral Analysis (HOSA) - has been identified as a potential candidate for improving some aspects of forensic speaker identification tasks. Presented in this thesis is a study investigating the application of HOSA to improve the robustness of current ASR techniques in the presence of additive Gaussian noise. Results from our investigations reveal that incremental improvements in each of these aspects related to automatic and forensic identification are achievable.

The aim of this thesis is to assess the impact of long term non-contemporaneity on the strength of forensic speech evidence. Speakers experience age-related changes to the voice over long delays and this time also presents the opportunity for social factors to vary. These changes are shown to impact on speech parameters used in forensic analyses. Using longitudinal data from the Up documentary series, this thesis analyses the effects of aging on forensically useful acoustic parameters in eight speakers at five seven-year intervals between ages 21 and 49. The investigation reveals significant age-related changes in real-time across adulthood. Frequencies of the first three formants in monophthongs /i: ɪ e a ɑ: ʌ ɒ ʊ & u:/ and diphthongs /eɪ & aɪ/ show comprehensive reduction. For monophthongs, F1 exhibits mean change of 8.5%, greater than F2 and F3 at 3.7% and 2.2% respectively. Vowel quality also impacts on magnitude of change in each formant. Estimations based on this data suggest that vocal tract extension and restricted articulator movement are probable drivers for acoustic change, operating on different timelines. Counter-examples to this aging pattern can generally be explained by social factors, as a result of mobility or in accordance with mainstream changes in a variety. Strength of evidence estimates for these non-contemporaneous data are calculated using a numerical likelihood ratio (LR) approach. Age-related changes result in weaker and fewer correct LRs with greater length delays. Cubic coefficients of diphthong formants are investigated in line with a formant dynamic approach. These LR tests show promising results and resilience to aging, especially in F1; tentatively suggesting that, for these speakers, some speaker-specific behaviour pervades in spite of physiological changes. This analysis raises several questions with regards to applying an overtly numerical LR approach where there is apparent mismatch between forensic samples. The effect of aging on an ASR system (BATVOX) is also tested for six male subjects. The system measures Mel-frequency cepstral coefficient (MFCC) parameters that reflect the physical properties of the vocal tract. Predicted degradation of the system’s performance with increasing age is apparent. The reduction in performance is significant, varies between speakers, and is striking in longer delays for all speakers. The degradation in strength of evidence for acoustic data from monophthongs and formant dynamic coefficients, as well as that for the ASR system, demonstrates that aging presents a real problem for forensic analysis in non-contemporaneous cases. Furthermore, aging also presents issues for speech databases for the purpose of assessing strength of evidence, where further research into distributions of parameters in different age groups is warranted.

This thesis advances understanding of the forensic value of the automatic speech parameters by addressing the following question: what is the potentiality of the speech cepstrum as a forensic-acoustic parameter? Despite many advances in automatic speech and speaker recognition, robust and unconstrained progress in technical forensic speaker identification has been partly impeded by our incomplete understanding of the interaction and relation between forensic phonetics and the techniques employed in state-of-the-art automatic speech and speaker recognition. The posed question underlies the recurrent and longstanding issue of acoustic parameterisation in the area of forensic phonetics, where 1) speaker identification often must be carried out under less than optimal conditions, and 2) views differ on the usefulness and trustworthiness of the formant frequency measurements. To this end, a new formulation for the forensic evaluation of speech data was derived which is effectively a spectral likelihood ratio with enhanced sensitivity to the local peaks of the formant structure of the speech spectrum of vowel sounds, while retaining the characteristics of the Bayesian framework. This new hybrid formula was used together with a novel approach, which is founded on a statistically-based matched-pairs technique to account for various levels of variation inherent in speech recordings, thereby providing a spectrally meaningful measure of variations between two speech spectra and hence the true worth of speech samples as forensic evidence. The experimental results are obtained based on a forensically-realistic database of a relatively large population of 297 native speakers of Japanese. In sum, the research conducted in this thesis is a major step forward in advancing the forensic-phonetic field which broadens the objective basis of the forensic speaker identification. Beyond advancing knowledge in the field, the semi data-independent nature of the new formula ultimately has great implications in technical forensic speaker identification. It also provides us with a valuable biometric tool with both academic and commercial potential in crime investigation in a field which is already suffering from the lack of adequate data.

The framework of the present PhD dissertation is the area that results from the overlap between the field of variationist sociolinguistics and forensic linguistics, which mainly concerns the study of variation between different individuals –inter-speaker variation– and variation within a single individual –intra-speaker variation– for forensic purposes. The primary objective of the present dissertation is twofold. On the one hand, it proposes a protocol for the creation of an Index of Idiolectal Similitude (IIS) for the phonological module of English that can effectively determine whether two oral samples show inter-speaker variation –which would indicate that the samples have been produced by two different individuals– or intra-speaker variation –which would allow to conclude that the samples have been produced by the same individual. On the other hand, the analysis of the fourteen variables proposed in a corpus that contains data on sixteen speakers and that is stratified according to measurement time –as a result of a real time study–, language contact and gender, provides an important contribution to the Base Rate knowledge, which constitutes one of the main challenges of current forensic linguistics. Results show that inter-speaker variation is generally higher than intra-speaker variation, and that a speaker’s idiolectal style remains relatively stable over time. Therefore, the IIS is presented as an innovative quantitative tool which, together with other quantitative and qualitative techniques that the linguist acting as expert witness may have at their disposition, can help reach a conclusion regarding the probability of two samples having been produced or not by the same speaker.
Aquesta tesi doctoral s’emmarca dins l’àrea comú on es troben els camps de la sociolingüística de la variació i la lingüística forense, en la qual es troba l’estudi de la variació entre diferents individus –variació inter-parlant– i la variació en del mateix individu –variació intra-parlant– amb finalitats forenses. La investigació té dos objectius principals. D’una banda, es proposa el protocol per a la creació d’un Índex de Similitud Idiolectal (ISI) per al mòdul fonològic de l’anglès que pot determinar de manera efectiva si dues mostres orals mostren variació inter-parlant –que indicaria que les mostres haurien estat produïdes per dos individus diferents– o variació intra-parlant –la qual cosa portaria a concloure que les mostres haurien estat produïdes pel mateix individu. D’altra banda, l’anàlisi de les catorze variables proposades en un corpus que conté setze parlants i que està estratificat per temps de mesura –com a resultat d’un estudi en temps real–, contacte de llengües i gènere biològic, comporta una contribució important a la referència de distribució poblacional (Base Rate Knowledge) que constitueix un dels grans reptes de la lingüística forense actual. Els resultats mostren que la variació inter-parlant és generalment més alta que la intra-parlant, i que l’estil idiolectal d’un individu es manté relativament estable malgrat el pas del temps. Per tant, l’ISI es presenta com una eina quantitativa innovadora que, juntament amb altres tècniques quantitatives i qualitatives que el lingüista forense pot tenir a la seva disposició, pot ajudar a prendre una decisió sobre la probabilitat que dues mostres hagin estat produïdes o no pel mateix parlant.

The performance of forensic speaker recognition systems degrades significantly in the presence of environmental noise and reverberant conditions. This research developed new techniques to improve forensic speaker recognition performance under these conditions using fusion feature extraction techniques and speech enhancement based on the independent component analysis algorithm. A range of forensic speaker recognition applications will benefit from the research outcomes including criminal investigations and law enforcement agencies.

This dissertation is aimed at investigating the impact of postural changes within speakers on the acoustic speech signal to complement research on articulatory changes under the same conditions. The research is therefore relevant for forensic phonetics, where quantifying within-speaker variation is vital for the accuracy of speaker comparison. To this end, two acoustic studies were carried out to quantify the influence of five head positions and three body orientations on the acoustic speech signal. Results show that there is a consistent change in the third formant, a change which was most evident in the body orientation measurements, and to a lesser extent in the head position data. Analysis of the results with respect to compensation strategies indicates that speakers employ different strategies to compensate for these perturbations to their vocal tract. Some speakers did not exhibit large differences in their speech signal, while others appeared to compensate much less. Across all speakers, the effect was much stronger in what were deemed ‘less natural’, postures. That is, speakers were apparently less able to predict and compensate for the impact of prone body orientation on their speech than for that of the more natural supine orientation. In addition to the acoustic studies, a perception experiment assessed whether listeners could make use of acoustic cues to determine the posture of the speaker. Stimuli were chosen with, by design, stronger or weaker acoustic cues to posture, in order to elicit a possible difference in identification performance. Listeners were nevertheless not able to identify above chance whether a speaker was sitting or lying in prone body orientation even when hearing the set with stronger cues. Further combined articulatory and acoustic research will have to be carried out to disentangle which articulatory behaviours correlate with the acoustic changes presented in order to draw a more comprehensive picture of the effects of postural variation on speech.

This thesis explores the historical trends of persuasion as it functions in the competitive forensic setting, looking at the structures used as well as the topics of the speeches. Persuasion plays a large role in our academic and daily lives, which stresses the importance of studying this area due to the large role it plays in our society. This thesis explores the persuasive speeches in the final round of the Interstate Oratorical Association competition from 1970, 1980, 1990, 2000 and 2010 to document the historical trends of persuasive strategies used as a representation of the role forensics fills in our understanding of persuasive trends.

The change of a vehicle’s velocity due to an impact, DeltaV (v) is often calculated and used in the scientific investigation of road traffic collisions. Two types of model are in common use to achieve this purpose, those based on the conservation of linear and angular momentum and the CRASH model which also considers the conservation of energy. It is shown that CRASH and major implementations of the momentum models are equivalent provided certain conditions are satisfied. Explicit conversions between the main variants of the models are presented. A method is also presented which describes a new formula for determining the total work performed in causing crush to a particular vehicle. This has the advantage of incorporating restitution effects and yields identical results to the momentum only models. Although the CRASH model has received adverse criticism due to perceived inaccuracies in the results, little work has been performed to determine the theoretical limitations on accuracy. This thesis rectifies that shortcoming. A Monte Carlo simulation and analytical model are developed here to provide two independent methods for determining the overall accuracy of the CRASH method. The principal direction of force was found to be the most likely to introduce error based on the CRASH assessment. It is shown how this and other sources of error in the CRASH model can be quantified for a particular collision suggesting priorities for minimising the overall uncertainty. The data from a series of well known crash tests are used with each of the models to provide comparison and validation data. It is recognised that without additional data velocity change is of limited use for forensic investigation. However DeltaV can be used as a proxy for acceleration and is particularly useful in studies involving injury causation. A method is also presented here which uses the change in velocity sustained by a vehicle in a planar collision to estimate the velocities of a vehicle before and after a collision. This method relies solely on conservation laws and is also applicable to situations where the coefficient of restitution is non-zero. An extension to the method is also described which allows an initial estimate to be modified to generate more realistic directions of force. This extension has the desirable effect of reducing uncertainty in the estimation of the direction of force which significantly improves the overall accuracy.

Orientador: Plínio Almeida Barbosa
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Estudos da Linguagem
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Resumo: Esta pesquisa investiga a eficácia de um conjunto de medidas acústicas para o reconhecimento da fala de um indivíduo em um grupo de dez falantes do português brasileiro. Um sujeito desse grupo foi sorteado e nomeado o "criminoso". Entre as medidas usadas na pesquisa estão, as frequências dos dois primeiros formantes das vogais, a frequência fundamental média, a duração de unidades do tamanho da sílaba e da vogal, a dinamicidade dos formantes e o desvio padrão de durações de intervalos consonânticos ('delta'C). Todos os trechos escolhidos são de entrevistados divididos em dois grupos, (i) entrevistas ao ar livre e (ii) gravações telefônicas (de celular para celular). Os indivíduos consistem em falantes do português brasileiro das regiões do estado de São Paulo, Rio Grande do Sul, Pará e Bahia. Nesta pesquisa fazemos um apanhado histórico da Fonética Forense, os métodos de análise utilizados ao longo história e também quais parâmetros acústicos mais usados para diferentes contextos de gravação, direta e por celular e quais deles foram mais significantes na pesquisa. Em nossos resultados, os parâmetros que menos sofreram variação com a mudança de canal de transmissão foram parâmetros de ritmo e tempo, como duração, taxa de elocução, 'delta'C; e um parâmetro que mede a dinamicidade do formante, que foi a taxa de movimento do segundo formante. As medidas temporais da pesquisa, por serem as mais variáveis inter-sujeito, tiveram grande poder discriminador. Os testes estatísticos apontaram que três dos indivíduos estudados, apresentavam semelhanças com o "criminoso"
Abstract: The aim of this research is to use some acoustic techniques for recognizing a subject in a group of ten speakers of the Brazilian Portuguese variety and pointing out what are the most relevant acoustic parameters for speaker recognition in that group. The analysis of the first two formants for the oral vowels, fundamental frequency, speech length, formant movement rate, syllable-sized duration, intensity and 'delta'C (standard deviation of consonantal interval durations of the collected samples) will help identifying an individual from within the group. All the samples are from interviews made in a poorly treated acoustic environment and into a mobile phone. Moreover, the samples of one the speakers (the "criminal"), which were collected in an acoustically-treated room, will simulate the questioned pattern of the forensic situation
Mestrado
Linguistica
Mestra em Linguística

In recent years, the public has seen a rise in recorded footage of violent encounters between police and Black American citizens, partially due to technology such as cell phones, dash-cameras, and body-cameras. This linguistic study examines how these encounters get escalated to the point of violence by asking 1) what kind of directives were used, 2) how were they responded to, 3) how the directives contributed to escalation, and 4) how might power and authority have played a role. I use two case studies to analyze directives and their responses. Findings reveal that repetition of directives on the part of the officers, as well as the rejections to those directives on the part of the motorists tend to aggravate the conversation. I conclude that a variety of directives may represent a variety of reasons the officer might have for a motorist to comply with their directives and that police authority might be better understood and agreed to by the motorist if a variety of linguistic resources were used.

Orientador: Plínio Almeida Barbosa
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Estudos da Linguagem
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Resumo: Esta dissertação avalia os efeitos causados ao sinal da fala pela transmissão telefônica de linhas móveis e, com isso, busca determinar o grau de modificação fonético-acústica intralocutor causado pelo filtro de banda do canal telefônico à voz habitual e os efeitos que a transmissão telefônica exerce sobre as vogais orais do português brasileiro, pelo estudo de parâmetros acústicos que são afetados por esse tipo de transmissão. As análises investigaram quais características acústicas eram modificadas e quais permaneciam inalteradas na fala de indivíduos diante da utilização de telefones celulares quando comparadas a gravações diretas. O corpus constitui-se de gravações de 10 locutores do sexo masculino, realizadas de forma simultânea nas condições via celular e direta, pelo posicionamento de um microfone em frente aos sujeitos enquanto falavam ao celular. As vogais orais do português brasileiro foram transcritas e segmentadas e, posteriormente, foi utilizado o script ForensicDataTrecking para extração automática das seguintes classes de parâmetros: frequência dos três primeiros formantes (F1, F2 e F3), frequência fundamental (F0), ênfase espectral, frequência de base da fundamental (baseline) e duração interpicos de F0 presentes no discurso. Foram conduzidas análises acústicas com o objetivo investigar os efeitos da transmissão telefônica sobre as vogais orais do português brasileiro, sobre os locutores e no espaço vocálico dos locutores. As análises foram validadas estatisticamente. Para a análise do efeito da transmissão telefônica sobre as vogais orais do português brasileiro, os resultados revelam alterações nas frequências do primeiro e o terceiro formante de, aproximadamente, 14%, na condição telefônica. Em relação às frequências do segundo formante, os resultados da análise de dispersão mostraram que a transmissão telefônica agiu de forma a aumentar artificialmente as frequências de vogais com baixos valores de F2 e a diminuir as frequências de vogais com altos valores de F2. Dos parâmetros acústicos investigados na análise dos efeitos da transmissão telefônica sobre os locutores, apenas a baseline e a duração interpicos de F0 não apresentaram diferenças estatisticamente significativas entre as duas condições de gravação, indicando robustez aos efeitos da transmissão telefônica e podendo ser considerados como parâmetros eficazes na análise forense. Esta análise revelou, também, que a transmissão telefônica agia de maneira distinta nos sujeitos, o que permitiu que fossem agrupados a depender do parâmetro investigado. A análise do efeito telefônico no espaço vocálico dos sujeitos complementou os resultados das análises anteriores. De modo geral, observou-se um abaixamento global do espaço vocálico na gravação telefônica, influenciado pelo aumento nas frequências de F1. A diminuição dos valores de F2 para as vogais anteriores e o aumento nos valores deste formante para vogais posteriores comprimiu o espaço vocálico da maioria dos sujeitos. As modificações nas disposições das vogais têm implicações perceptuais, uma vez que o abaixamento e redução do espaço vocálico fizeram com que as vogais se situassem proximamente a regiões centrais, podendo soar como mais abertas no telefone celular
Abstract: This dissertation evaluates the effects to speech signal due to telephone transmission of mobile phones and seeks to determine the degree of intra-speaker acoustic-phonetic modification caused by the mobile phone band-pass filter to the speech signal and the telephone transmission effects over the Brazilian Portuguese oral vowels by the study of the acoustic parameters affected by this kind of transmission. The analysis investigated which are the acoustic cues which are modified and which cues remain undifferentiated in the speaker's speech by the use of a mobile phone in comparison to direct recordings. The corpus used consists of simultaneous recordings of 10 male speakers in two conditions: via mobile phone and face-to-face, by placing a microphone directly in front of the subjects. The Brazilian Portuguese oral vowels were segmented and transcribed and the ForensicDataEvaluator script was used to automatically extract the following acoustic parameters: three first formants frequencies (F1, F2 and F3), median of fundamental frequency (F0), spectral emphasis, fundamental frequency baseline and F0 inter-peaks duration. The acoustic analyses aimed at investigating the telephone transmission effects over the Brazilian Portuguese oral vowels, over the speakers and at the speakers¿ vowel space. The analyses were supported statistically. The analysis of the telephone transmission effect over the Brazilian Portuguese oral vowels showed variations of 14% in the frequencies of the first and the third formants. The analysis of the scatter plot of F2 values showed that the mobile phone band-pass filtering has an effect of shifting upwards vowels with low values of F2 and shifting downwards vowels with high values of F2. For the analysis of the telephone transmission effects over the speaker only the acoustic parameters "fundamental frequency baseline" and "F0 inter-peaks duration" did not show any difference statistically significant between the two recording conditions, demonstrating robustness to the telephone transmission effects, which make them able to be considered as powerful parameters for forensic analysis. This analysis also revealed that the telephone transmission affects the speakers in different ways, which set them into different groups of speakers depending on the parameter analyzed. The analysis of the telephone effect in the speakers¿ vowel space shed some light on the previous analyses. In general, the increase of the F1 values in the mobile phone situation caused a global downward displacement of the vowel space. The decrease of the F2 values for the front vowels and the increase of the values of this formant for back vowels reduced the area of the vowel space for the most of the subjects. The vowels rearrangement at the vowel space in the telephone situation has some perceptual implications, since the lowering and reduction of the vowel space made the vowels be placed at its center, which could result in hearing these vowels as more open over the mobile phone
Mestrado
Linguistica
Mestra em Linguística

Le tribunal populaire de l’Héliée ne constitue pas seulement une des institutions les plus importantes de la démocratie athénienne ; il reflète la structure même du régime démocratique d’Athènes aux Ve et IVe siècles. Cependant, l’attribution, par certaines sources, de l’origine de l’Héliée aux réformes de Solon et à l’établissement d’un régime censitaire remet en question son caractère d’emblée démocratique et populaire. Le sujet est d’un intérêt particulier, étant donné que chaque année six mille Athéniens, non professionnels, étaient tirés au sort et formaient l’Héliée. Ce fait lui donne une importance politique prépondérante, qui est visible en particulier à partir de la fin du Ve siècle. L’activité judiciaire constitue un élément si important de la vie politique de l’Athénien et connaît une telle augmentation au cours du IVe siècle qu’on a souvent l’impression que le conflit politique se déplace de l’espace de l’Assemblée à l’Héliée. Ces problématiques nous conduisent à saisir la période de la création de l’institution de l’Héliée et le régime auquel elle est liée, puis à éclairer son caractère politique, tant du point de vue de son fonctionnement et des procès qui sont jugés devant ses tribunaux que du rôle de ses tribunaux dans la vie politique d’Athènes. L’étude conjointe des sources littéraires et épigraphiques permet de conclure qu’au-delà du rôle primordial de l’Assemblée du peuple dans la prise des décisions politiques, on trouve une autre institution fondée sur une base populaire qui participe à l’organisation politique de la cité et qui est étroitement liée au développement de la démocratie athénienne
The court of Heliaia is not only one of the most important institutions of Athenian democracy, but also reflects the structure of the democratic constitution of Athens in the fifth and fourth centuries. However, the fact that several sources attribute its origins to the reforms of Solon and the establishment of a timocratic constitution questions its explicit democratic and popular character. The issue is particularly interesting, given that each year six thousand non-professional Athenians are allotted and form the People’s Court. This fact implies that Heliaia is of prominent political significance, especially since the late fifth century. The importance of the judicial activity in the political life of Athenians, as well as its notable increase during the fourth century, were such that we often have the impression that the political conflicts occur not only in the Assembly but also in the People’s Court. Motivated from these issues, we first search for the period of the establishment of the institution of Heliaia and its historical context. Additionally, we aim to clarify its political character from the perspective of its function and trials, as well as from the perspective of its role in the political life of Athens. Indeed, the study of the literary and epigraphic sources allows us to conclude that, beyond the primary role of the Assembly of the People in the political decisions, there is another institution of popular composition involved in the political organization of the city, which is directly linked to the development of Athenian democracy

La presente investigación pretende contribuir a establecer la individualidad del habla de los hablantes bilingües de catalán y de castellano a partir del análisis de los parámetros fonético-acústicos analizados habitualmente en la práctica de la comparación forense de habla y estudiar los efectos, en el nivel acústico, que el uso de una lengua u otra produce en estos parámetros. Por lo tanto, se pretende proporcionar a los especialistas en fonética forense nuevos datos fonético-acústicos para que puedan comparar con un mayor grado de certeza muestras de habla dubitadas e indubitadas en distintas lenguas.
La recerca que es presenta vol contribuir a establir la individualitat de la parla dels parlants bilingües de català i de castellà a partir de l’anàlisi dels paràmetres foneticoacústics analitzats habitualment en la pràctica de la comparació forense de parla i estudiar els efectes, en el nivell acústic, que l’ús d’una llengua o l’altra provoca en aquests paràmetres. Per tant, es vol dotar els especialistes en fonètica forense de dades foneticoacústiques noves que els permetin comparar, amb un grau més elevat de certesa, mostres de parla dubitades i indubitades en llengües diferents.
This research aims to contribute to establish the individuality of the speech of bilingual speakers in Catalan and Spanish from the analysis of acoustic-phonetic parameters commonly analyzed in the practice of forensic speech comparison and to study the effects, on the acoustic level, that the use of one language or the other produces in these parameters. Therefore, it tries to provide new acoustic-phonetic data for specialists in forensic phonetics to be compared with a greater degree of certainly known and unknown speech samples in different languages.

Dans le cadre d’une approche philosophique et épistémologique, qui privilège le point de vue rhétorique sur l’argumentation et la ligne de pensée Aristote-Vico-Perelman, la thèse essaye d’analyser la construction de la subjectivité dans le discours argumentatif. Je cherche à montrer qu’il est possible de tracer une théorie de l’argumentation dans laquelle subjective n’est pas synonyme de fallacieuse.

En général, la thèse analyse le rôle de celui qui parle et de celui qui écoute dans l’argumentation et dans tous les discours. Je vais soutenir est que la dimension personnelle n’est pas un élément qu’il faut supprimer mais, au contraire, un élément essentiel du discours argumentatif.

Une approche rhétorique au problème du sujet se base sur une intuition fondamentale de la rhétorique d’Aristote .Comme nous le savons, dans le premier livre de la Rhétorique, Aristote affirme que le discours (logos) est composé (synkeimai) de trois éléments :l’orateur, le sujet traité et l’auditoire .Au même temps la rhétorique est composée des trois éléments :Logos, Pathos et Ethos. La pratique linguistique inclut la dimension émotive, l’orateur et l’auditoire, qui sont des éléments discursifs. De même, l’ethos et le pathos ne sont pas des moyens de preuves irrationnelles ou des fallacies. On verra que cette idée implique un système philosophique et épistémologique assez différent du système normativiste des théories contemporaines :cela implique de revenir sur le concept de rationalité et sur le rapport entre la rationalité, la praxis et son incertitude essentielle.

Pour question de temps, la thèse ne parle pas de pathos. Elle s’occupe de l’ethos soit du point de vue de celui qui parle (Partie I) soit du point de vue de l’auditoire (Partie II).

Dans la première partie, on analyse la question de la rationalité rhétorique et des paralogismes et les définitions historiques de la dimension personnelle de l’argumentation (ethos, personne, ad hominem).

Dans la deuxième, on analyse le rapport entre la dimension personnelle, le sens commun, la vérité, la certitude et la fides.

En conclusion, on soutiendra que l’ethos est soit une pistis technique de la rhétorique, soit une des conditions préalables du discours même.

Doctorat en Langues et lettres
info:eu-repo/semantics/nonPublished

This thesis sets out to investigate whether or not forensic speaker identification can be performed, using forensically realistic data, which is natural and non-contemporaneous speech. To date, there is no forensic phonetic research which tests how accurately speakers can be discriminated on the basis of their voice under forensically realistic conditions, despite the fact that the use of speech recordings for forensic investigation or as a part of evidence in court is not an unusual practice today. This research thus aims to provide the first test of the accuracy of realistic forensic speaker identification using centre frequencies of formants, which are today the most commonly used acoustic parameter in actual forensic speaker identification today. The current state of forensic speaker identification in Japan also signifies this research. Forensic speaker identification in Japan has relied on visual examination of spectrograms and occasional use of the automatic speaker recognition technique. The research on forensic speaker identification also concentrates on the application of the automatic speaker recognition technique, and no linguistic analysis or interpretation of speech data has been included. This thesis therefore will serve as the first linguistic analysis in Japanese forensic speaker identification research. This thesis frrstly examines what segment f formant combinations are more promising as the speaker identification parameter. Those parameters are then incorporated, and how accurately they discriminate two speech samples is tested. For the testing, three different statistical approaches are presented and examined. As result, the distance based approach using likelihood ratio as the score for discrimination test (likelihood ratio-based distance method) was found to be most effective. The results of this testing showed that speakers can indeed be discriminated on the basis of their formant frequencies, as long as enough number of parameters are incorporated. With this approach incorporating six parameters, the successful discrimination rates were found to be approximately %.7% for positive discrimination (discriminating two different speakers) and 90% for negative discrimination (identifying the same speaker), when the threshold was set at likelihood ratio 1.

This thesis aims to thoroughly describe the temporal characteristics of spoken Czech by means of phone durations and their changes under the influence of several prosodic and segmental factors, such as position in a higher unit (syllable, word or prosodic phrase), length of the higher unit, segmental environment, structure of the syllable or phrase-final lengthening. The speech material comes from a semi-spontaneous corpus of scripted dialogues comprising 4046 utterances by 34 speakers. The descriptions are afterwards used for the creation of a rule-based temporal model, which provides a baseline for analysing local articulation rate contours and their speaker-specificity. The results indicate, that systematic speaker-specific differences can be found in the segmental domain, as well as in the temporal contours. Moreover, speaker identification potential of articulation rate and global temporal features is also assessed. Keywords: temporal characteristics, temporal modelling, phone duration, speaker identification, Czech