Physiologically-Motivated Feature Extraction Methods for Speaker Recognition

Speaker recognition has received a great deal of attention from the speech community, and significant gains in robustness and accuracy have been obtained over the past decade. However, the features used for identification are still primarily representations of overall spectral characteristics, and thus the models are primarily phonetic in nature, differentiating speakers based on overall pronunciation patterns. This creates difficulties in terms of the amount of enrollment data and complexity of the models required to cover the phonetic space, especially in tasks such as identification where enrollment and testing data may not have similar phonetic coverage. This dissertation introduces new features based on vocal source characteristics intended to capture physiological information related to the laryngeal excitation energy of a speaker. These features, including RPCC, GLFCC and TPCC, represent the unique characteristics of speech production not represented in current state-of-the-art speaker identification systems. The proposed features are evaluated through three experimental paradigms including cross-lingual speaker identification, cross song-type avian speaker identification and mono-lingual speaker identification. The experimental results show that the proposed features provide information about speaker characteristics that is significantly different in nature from the phonetically-focused information present in traditional spectral features. The incorporation of the proposed glottal source features offers significant overall improvement to the robustness and accuracy of speaker identification tasks

Analysis and detection of human emotion and stress from speech signals

Ph.DDOCTOR OF PHILOSOPH

Exploring the use of Technology for Assessment and Intensive Treatment of Childhood Apraxia of Speech

Given the rapid advances in technology over the past decade, this thesis examines the potential for automatic speech recognition (ASR) technology to expedite the process of objective analysis of speech, particularly for lexical stress patterns in childhood apraxia of speech. This dissertation also investigates the potential for mobile technology to bridge the gap between current service delivery models in Australia and best practice treatment intensity for CAS. To address these two broad aims, this thesis describes three main projects. The first is a systematic literature review summarising the development, implementation and accuracy of automatic speech analysis tools when applied to evaluation and modification of children’s speech production skills. Guided by the results of the systematic review, the second project presents data on the accuracy and clinical utility of a custom-designed lexical stress classification tool, designed as part of a multi-component speech analysis system for a mobile therapy application, Tabby Talks, for use with children with CAS. The third project is a randomised control trial exploring the effect of different types of feedback on response to intervention for children with CAS. The intervention was designed to specifically explore the feasibility and effectiveness of using an app equipped with ASR technology to provide feedback on speech production accuracy during home practice sessions, simulating the common service delivery model in Australia. The thesis concludes with a discussion of future directions for technology-based speech assessment and intensive speech production practice, guidelines for future development of therapy tools that include more game-based practice activities and the contexts in which children can be transferred from predominantly clinician-delivered augmented feedback to ASR-delivered right/wrong feedback and continue to make optimal gains in acquisition and retention of speech production targets

Stress recognition from speech signal

Předložená disertační práce se zabývá vývojem algoritmů pro detekci stresu z řečového signálu. Inovativnost této práce se vyznačuje dvěma typy analýzy řečového signálu, a to za použití samohláskových polygonů a analýzy hlasivkových pulsů. Obě tyto základní analýzy mohou sloužit k detekci stresu v řečovém signálu, což bylo dokázáno sérií provedených experimentů. Nejlepších výsledků bylo dosaženo pomocí tzv. Closing-To-Opening phase ratio příznaku v Top-To-Bottom kritériu v kombinaci s vhodným klasifikátorem. Detekce stresu založená na této analýze může být definována jako jazykově i fonémově nezávislá, což bylo rovněž dokázáno získanými výsledky, které dosahují v některých případech až 95% úspěšnosti. Všechny experimenty byly provedeny na vytvořené české databázi obsahující reálný stres, a některé experimenty byly také provedeny pro anglickou stresovou databázi SUSAS.Presented doctoral thesis is focused on development of algorithms for psychological stress detection in speech signal. The novelty of this thesis aims on two different analysis of the speech signal- the analysis of vowel polygons and the analysis of glottal pulses. By performed experiments, the doctoral thesis uncovers the possible usage of both fundamental analyses for psychological stress detection in speech. The analysis of glottal pulses in amplitude domain according to Top-To-Bottom criterion seems to be as the most effective with the combination of properly chosen classifier, which can be defined as language and phoneme independent way to stress recognition. All experiments were performed on developed Czech real stress database and some observations were also made on English database SUSAS. The variety of possibly effective ways of stress recognition in speech leads to approach very high recognition accuracy of their combination, or of their possible usage for detection of other speaker’s state, which has to be further tested and verified by appropriate databases.

Automatic Screening of Childhood Speech Sound Disorders and Detection of Associated Pronunciation Errors

Speech disorders in children can affect their fluency and intelligibility. Delay in their diagnosis and treatment increases the risk of social impairment and learning disabilities. With the significant shortage of Speech and Language Pathologists (SLPs), there is an increasing interest in Computer-Aided Speech Therapy tools with automatic detection and diagnosis capability. However, the scarcity and unreliable annotation of disordered child speech corpora along with the high acoustic variations in the child speech data has impeded the development of reliable automatic detection and diagnosis of childhood speech sound disorders. Therefore, this thesis investigates two types of detection systems that can be achieved with minimum dependency on annotated mispronounced speech data. First, a novel approach that adopts paralinguistic features which represent the prosodic, spectral, and voice quality characteristics of the speech was proposed to perform segment- and subject-level classification of Typically Developing (TD) and Speech Sound Disordered (SSD) child speech using a binary Support Vector Machine (SVM) classifier. As paralinguistic features are both language- and content-independent, they can be extracted from an unannotated speech signal. Second, a novel Mispronunciation Detection and Diagnosis (MDD) approach was introduced to detect the pronunciation errors made due to SSDs and provide low-level diagnostic information that can be used in constructing formative feedback and a detailed diagnostic report. Unlike existing MDD methods where detection and diagnosis are performed at the phoneme level, the proposed method achieved MDD at the speech attribute level, namely the manners and places of articulations. The speech attribute features describe the involved articulators and their interactions when making a speech sound allowing a low-level description of the pronunciation error to be provided. Two novel methods to model speech attributes are further proposed in this thesis, a frame-based (phoneme-alignment) method leveraging the Multi-Task Learning (MTL) criterion and training a separate model for each attribute, and an alignment-free jointly-learnt method based on the Connectionist Temporal Classification (CTC) sequence to sequence criterion. The proposed techniques have been evaluated using standard and publicly accessible adult and child speech corpora, while the MDD method has been validated using L2 speech corpora

The Effect of Bilingual Proficiency in Indian English on Bilabial Plosive

Background: Bilingual speech production studies have highlighted that level of proficiency influences the acoustic-phonetic representation of phonemes in both languages (MacKay, Flege, Piske, & Schirru 2001; Zárate-Sández, 2015). The results for bilingual speech production reveal that proficient/early bilinguals produce distinct acoustic properties for the same phoneme in each language, whereas less proficient/late bilinguals produce acoustic properties for a phoneme that is closer to the native language (Flege et al., 2003; Fowler et al., 2008). Acoustic-phonetic studies for Hindi (L1) and Indian English (L2) for bilingual speakers have been understudied, and the level of proficiency has not been considered in Hindi and Indian English bilingual speakers. The present study aimed to measure the acoustic differences produced by bilingual speakers of varying proficiencies for Indian English on bilabial plosive and determine how the bilabial plosives are different from American English bilabial plosives. Methods: The sample size for this study was twenty-four. However, only twenty participants (eleven females) between the ages of eighteen and fifty, with normal speech and hearing, were recruited. The lack of recruitment of four more participants was due to the inability to find bilingual speakers who spoke Hindi as their first language and Indian English as their second language and COVID-19 restrictions imposed on recruitment (n=4). The participants were divided into three groups based on language and proficiency: a monolingual American English group, a proficient bilingual Hindi-Indian English group, and a less-proficient bilingual Hindi-Indian English group. The bilinguals were divided into a proficient and less proficient group based on the Language Experience and Proficiency Questionnaire (Marian, Blumenfeld, & Kaushanskaya, 2007). Following the screening, participants took part in a Nonword Repetition Task. Data were analyzed using Praat and Voice Sauce software. A linear mixed-effects model using R statistics was used for the statistical analysis. Results: Data from 20 participants (seven proficient bilingual speakers, five less-proficient bilingual speakers, and eight monolingual speakers) were included in the data analysis. Approximately four thousand repetitions were evaluated across the remaining participants. There were no significant main effects across the four dependent variables, but there was an interaction effect between group and phoneme on two dependent variables. The closure duration for proficient bilingual speakers compared to less-proficient bilingual speakers were significantly different between the voiceless unaspirated bilabial plosive (VLE) and voiceless aspirated bilabial plosive (VLH), as well as voiced unaspirated bilabial plosive (VE) and voiced aspirated bilabial plosive (VH). For spectral tilt, there was a significant difference between the VLE and VLH for proficient bilingual speakers compared to less proficient bilingual speakers. Discussion: The results of this study suggest that proficient bilingual speakers have a faster rate of speech in both their first language and second language. Therefore, it is difficult to provide information on whether this group has separate acoustic-phonetic characteristics for each phoneme for each language. In contrast, the less-proficient bilingual speakers seem to have a unidirectional relationship (i.e., first language influences the second language). Furthermore, the results of the acoustic characteristics for the control group i.e., monolingual American English speakers suggest that they may have acoustic-phonetic characteristics that represent a single acoustic-phonetic representation of bilabial plosive with their voicing contrast

Speech emotion recognition through statistical classification

O propósito desta dissertação é a discussão do reconhecimento de emoção na voz. Para este fim, criou-se uma base de dados validada de discurso emocional simulado Português, intitulada European Portuguese Emotional Discourse Database (EPEDD) e foram operados algoritmos de classificação estatística nessa base de dados. EPEDD é uma base de dados simulada, caracterizada por pequenos discursos (5 frases longas, 5 frases curtas e duas palavras), todos eles pronunciados por 8 atores—ambos os sexos igualmente representados—em 9 diferentes emoções (raiva, alegria, nojo, excitação, apatia, medo, surpresa, tristeza e neutro), baseadas no modelo de emoções de Lövheim. Concretizou-se uma avaliação de 40% da base de dados por avaliadores inexperientes, filtrando 60% dos pequenos discursos, com o intuito de criar uma base de dados validada. A base de dados completa contem 718 instâncias, enquanto que a base de dados validada contém 116 instâncias. A qualidade média de representação teatral, numa escala de a 5 foi avaliada como 2,3. A base de dados validada é composta por discurso emocional cujas emoções são reconhecidas com uma taxa média de 69,6%, por avaliadores inexperientes. A raiva tem a taxa de reconhecimento mais elevada com 79,7%, enquanto que o nojo, a emoção cuja taxa de reconhecimento é a mais baixa, consta com 40,5%. A extração de características e a classificação estatística foi realizada respetivamente através dos softwares Opensmile e Weka. Os algoritmos foram operados na base dados original e na base de dados avaliada, tendo sido obtidos os melhores resultados através de SVMs, respetivamente com 48,7% e 44,0%. A apatia obteve a taxa de reconhecimento mais elevada com 79,0%, enquanto que a excitação obteve a taxa de reconhecimento mais baixa com 32,9%.The purpose of this dissertation is to discuss speech emotion recognition. It was created a validated acted Portuguese emotional speech database, named European Portuguese Emotional Discourse Database (EPEDD), and statistical classification algorithms have been applied on it. EPEDD is an acted database, featuring 12 utterances (2 single-words, 5 short sentences and 5 long sentences) per actor and per emotion, 8 actors, both genders equally represented, and 9 emotions (anger, joy, disgust, excitement, fear, apathy, surprise, sadness and neutral), based on Lövheim’s emotion model. We had 40% of the database evaluated by unexperienced evaluators, enabling us to produce a validated one, filtering 60% of the evaluated utterances. The full database contains 718 instances, while the validated one contains 116 instances. The average acting quality of the original database was evaluated, in a scale from 1 to 5, as 2,3. The validated database is composed by emotional utterances that have their emotions recognized on average at a 69,6% rate, by unexperienced judges. Anger had the highest recognition rate at 79,7%, while disgust had the lowest recognition rate at 40,5%. Feature extraction and statistical classification algorithms were performed respectively applying Opensmile and Weka software. Statistical classification algorithms operated in the full database and in the validated one, best results being obtained by SVMs, respectively the emotion recognition rates being 48,7% and 44,0%. Apathy had the highest recognition rate: 79.0%, while excitement had the lowest emotion recognition rate: 32.9%