Developing Automated Feedback on Spoken Performance : Exploring the Functioning of Five Analytic Rating Scales Using Many-facet Rasch Measurement

Peer reviewe

The development of automatic speech evaluation system for learners of English

制度:新 ; 報告番号:甲3183号 ; 学位の種類:博士(教育学) ; 授与年月日:2010/11/30 ; 早大学位記番号:新547

Computer-based Assessment of Foreign Language Speaking Skills

In the frame of the current effort to establish an indicator of foreign language competency in Europe via the implementation of a language survey in 2011, a Conference on computer-based assessment (CBA) of speaking skills was held in Brussels in June 2010. The sponsors of this event, the Centre for Research on Lifelong Learning of the European Commission in Ispra and the Directorate General of Education and Culture, are pleased to put forward this report with the Conference proceedings. It is our hope that it can serve, not only to inform the implementation of the language survey, but also to assist Member States and their representatives in the task of gathering current evidence on the benefits and challenges linked to the implementation of CBA.JRC.DG.G.9-Econometrics and applied statistic

Second language pronunciation assessment: A look at the present and the future

Over three decades ago, Michael Canale summarized what he considered to be the challenges facing language assessment in the era of communicative language learning and teaching: Just as the shift in emphasis from language form to language use has placed new demands on language teaching, so too has it placed new demands on language testing. Evaluation within a communicative approach must address, for example, new content areas such as sociolin- guistic appropriateness rules, new testing formats to permit and encour- age creative, open-ended language use, new test administration procedures to emphasize interpersonal interaction in authentic situa- tions, and new scoring procedures of a manual and judgemental nature. (Canale, 1984: 79) Applied to second language (L2) pronunciation assessment, this descrip- tion remains highly relevant today, raising a number of important issues, such as: broadening the scope of pronunciation assessment beyond the focus on a single aspect of pronunciation (e.g. segmental accuracy) or a single standard (e.g. absence of a discernible nonnative accent); targeting pronunciation assess- ment for various interlocutors in interactive settings, for instance, outside a typical focus on academic performance by students in Western societies; as well as developing and fine-tuning novel assessment instruments and proce- dures. Above all, Canale’s description aptly summarizes an ongoing quest in language assessment to capture the authenticity and interactiveness of language use (e.g. Bachman, 1990; Bachman & Palmer, 2010). The contribu- tions to this edited volume address some of the challenges identified by Canale in innovative ways. Before summarizing these contributions, we hasten to add that no edited volume, including this one, can provide an exhaustive overview of all possible issues in L2 pronunciation assessment; most chapters in this volume are focused on testing or informal evaluative judgements of speech in real-world settings and not on classroom-based assessment, including diagnostic assessment or feedback on test takers’ per- formance. However, the range of topics, the variety of research methodologies and paradigms, and the scope of implications featured here make this volume a timely addition to the growing area of L2 pronunciation assessment

Modeling statistics ITAs’ speaking performances in a certification test

In light of the ever-increasing capability of computer technology and advancement in speech and natural language processing techniques, automated speech scoring of constructed responses is gaining popularity in many high-stakes assessment and low-stakes educational settings. Automated scoring is a highly interdisciplinary and complex subject, and there is much unknown about the strengths and weaknesses of automated speech scoring systems (Evanini & Zechner, 2020). Research in automated speech scoring has been centralized around a few proprietary systems owned by large testing companies. Consequently, existing systems only serve large-scale standardized assessment purposes. Application of automated scoring technologies in local assessment contexts is much desired but rarely realized because the system’s inner workings have remained unfamiliar to many language assessment professionals. Moreover, assumptions about the reliability of human scores, on which automated scoring systems are trained, are untenable in many local assessment situations, where a myriad of factors would work together to co-determine the human scores. These factors may include the rating design, the test takers’ abilities, and the raters’ specific rating behaviors (e.g., severity/leniency, internal consistency, and application of the rating scale). In an attempt to apply automated scoring procedures to a local context, the primary purpose of this study is to develop and evaluate an appropriate automated speech scoring model for a local certification test of international teaching assistants (ITAs). To meet this goal, this study first implemented feature extraction and selection based on existing automated speech scoring technologies and the scoring rubric of the local speaking test. Then, the reliability of the human ratings was investigated based on both Classical Test Theory (CTT) and Item Response Theory (IRT) frameworks, focusing on detecting potential rater effects that could negatively impact the quality of the human scores. Finally, by experimenting and comparing a series of statistical modeling options, this study investigated the extent to which the association between the automatically extracted features and the human scores could be statistically modeled to offer a mechanism that reflects the multifaceted nature of the performance assessment in a unified statistical framework. The extensive search for the speech or linguistic features, covering the sub-domains of fluency, pronunciation, rhythm, vocabulary, grammar, content, and discourse cohesion, revealed that a small set of useful variables could be identified. A large number of features could be effectively summarized as single latent factors that showed reasonably high associations with the human scores. Reliability analysis of human scoring indicated that both inter-rater reliability and intra-rater reliability were acceptable, and through a fine-grained IRT analysis, several raters who were prone to the central tendency or randomness effects were identified. Model fit indices, model performance in prediction, and model diagnostics results in the statistical modeling indicated that the most appropriate approach to model the relationship between the features and the final human scores was a cumulative link model (CLM). In contrast, the most appropriate approach to model the relationship between the features and the ratings from the multiple raters was a cumulative link mixed model (CLMM). These models suggested that higher ability levels were significantly related to the lapse of time, faster speech with fewer disfluencies, more varied and sophisticated vocabulary, more complex syntactic structures, and fewer rater effects. Based on the model’s prediction on unseen data, the rating-level CLMM achieved an accuracy of 0.64, a Pearson correlation of 0.58, and a quadratically-weighted kappa of 0.57, as compared to the human ratings on the 3-point scale. Results from this study could be used to inform the development, design, and implementation for a prototypical automated scoring system for prospective ITAs, as well as providing empirical evidence for future scale development, rater training, and support for assessment-related instruction for the testing program and diagnostic feedback for the ITA test takers

Rater Cognition in L2 Speaking Assessment: A Review of the Literature

This literature review attempts to survey representative studies within the context of L2 speaking assessment that have contributed to the conceptualization of rater cognition. Two types of studies are looked at: 1) studies that examine how raters differ (and sometimes agree) in their cognitive processes and rating behaviors, in terms of their focus and feature attention, their approaches to scoring, and their treatment of the scoring criteria and non-criteria relevant aspects and features of the speaking performance; 2) studies that explore why raters differ, through the analysis of the interactions between several rater background factors (i.e., rater language background, rater experience and rater training) and their rating behaviors and decision-making processes. The two types of studies have improved our understanding of the nature and the causes of rater variability in their perception and evaluation of L2 speech. However, very few of those studies has drawn on existing theories of human information processing and research on strategy use, which can explain on a cognitive-processing (Purpura, 2014) level what goes on in raters’ mind during assessment. It is argued as a final conclusion that only based on established frameworks of human information processing and research on (meta)cognitive strategy use can rater cognition be explored with more depth and breadth

Automated assessment of second language comprehensibility: Review, training, validation, and generalization studies

Whereas many scholars have emphasized the relative importance of comprehensibility as an ecologically valid goal for L2 speech training, testing, and development, eliciting listeners’ judgments is time-consuming. Following calls for research on more efficient L2 speech rating methods in applied linguistics, and growing attention toward using machine learning on spontaneous unscripted speech in speech engineering, the current study examined the possibility of establishing quick and reliable automated comprehensibility assessments. Orchestrating a set of phonological (maximum posterior probabilities and gaps between L1 and L2 speech), prosodic (pitch and intensity variation), and temporal measures (articulation rate, pause frequency), the regression model significantly predicted how naïve listeners intuitively judged low, mid, high, and nativelike comprehensibility among 100 L1 and L2 speakers’ picture descriptions. The strength of the correlation (r = .823 for machine vs. human ratings) was comparable to naïve listeners’ interrater agreement (r = .760 for humans vs. humans). The findings were successfully replicated when the model was applied to a new dataset of 45 L1 and L2 speakers (r = .827) and tested under a more freely constructed interview task condition (r = .809)

CAPT를 위한 발음 변이 분석 및 CycleGAN 기반 피드백 생성

학위논문(박사)--서울대학교 대학원 :인문대학 협동과정 인지과학전공,2020. 2. 정민화.Despite the growing popularity in learning Korean as a foreign language and the rapid development in language learning applications, the existing computer-assisted pronunciation training (CAPT) systems in Korean do not utilize linguistic characteristics of non-native Korean speech. Pronunciation variations in non-native speech are far more diverse than those observed in native speech, which may pose a difficulty in combining such knowledge in an automatic system. Moreover, most of the existing methods rely on feature extraction results from signal processing, prosodic analysis, and natural language processing techniques. Such methods entail limitations since they necessarily depend on finding the right features for the task and the extraction accuracies. This thesis presents a new approach for corrective feedback generation in a CAPT system, in which pronunciation variation patterns and linguistic correlates with accentedness are analyzed and combined with a deep neural network approach, so that feature engineering efforts are minimized while maintaining the linguistically important factors for the corrective feedback generation task. Investigations on non-native Korean speech characteristics in contrast with those of native speakers, and their correlation with accentedness judgement show that both segmental and prosodic variations are important factors in a Korean CAPT system. The present thesis argues that the feedback generation task can be interpreted as a style transfer problem, and proposes to evaluate the idea using generative adversarial network. A corrective feedback generation model is trained on 65,100 read utterances by 217 non-native speakers of 27 mother tongue backgrounds. The features are automatically learnt in an unsupervised way in an auxiliary classifier CycleGAN setting, in which the generator learns to map a foreign accented speech to native speech distributions. In order to inject linguistic knowledge into the network, an auxiliary classifier is trained so that the feedback also identifies the linguistic error types that were defined in the first half of the thesis. The proposed approach generates a corrected version the speech using the learners own voice, outperforming the conventional Pitch-Synchronous Overlap-and-Add method.외국어로서의 한국어 교육에 대한 관심이 고조되어 한국어 학습자의 수가 크게 증가하고 있으며, 음성언어처리 기술을 적용한 컴퓨터 기반 발음 교육(Computer-Assisted Pronunciation Training; CAPT) 어플리케이션에 대한 연구 또한 적극적으로 이루어지고 있다. 그럼에도 불구하고 현존하는 한국어 말하기 교육 시스템은 외국인의 한국어에 대한 언어학적 특징을 충분히 활용하지 않고 있으며, 최신 언어처리 기술 또한 적용되지 않고 있는 실정이다. 가능한 원인으로써는 외국인 발화 한국어 현상에 대한 분석이 충분하게 이루어지지 않았다는 점, 그리고 관련 연구가 있어도 이를 자동화된 시스템에 반영하기에는 고도화된 연구가 필요하다는 점이 있다. 뿐만 아니라 CAPT 기술 전반적으로는 신호처리, 운율 분석, 자연어처리 기법과 같은 특징 추출에 의존하고 있어서 적합한 특징을 찾고 이를 정확하게 추출하는 데에 많은 시간과 노력이 필요한 실정이다. 이는 최신 딥러닝 기반 언어처리 기술을 활용함으로써 이 과정 또한 발전의 여지가 많다는 바를 시사한다. 따라서 본 연구는 먼저 CAPT 시스템 개발에 있어 발음 변이 양상과 언어학적 상관관계를 분석하였다. 외국인 화자들의 낭독체 변이 양상과 한국어 원어민 화자들의 낭독체 변이 양상을 대조하고 주요한 변이를 확인한 후, 상관관계 분석을 통하여 의사소통에 영향을 미치는 중요도를 파악하였다. 그 결과, 종성 삭제와 3중 대립의 혼동, 초분절 관련 오류가 발생할 경우 피드백 생성에 우선적으로 반영하는 것이 필요하다는 것이 확인되었다. 교정된 피드백을 자동으로 생성하는 것은 CAPT 시스템의 중요한 과제 중 하나이다. 본 연구는 이 과제가 발화의 스타일 변화의 문제로 해석이 가능하다고 보았으며, 생성적 적대 신경망 (Cycle-consistent Generative Adversarial Network; CycleGAN) 구조에서 모델링하는 것을 제안하였다. GAN 네트워크의 생성모델은 비원어민 발화의 분포와 원어민 발화 분포의 매핑을 학습하며, Cycle consistency 손실함수를 사용함으로써 발화간 전반적인 구조를 유지함과 동시에 과도한 교정을 방지하였다. 별도의 특징 추출 과정이 없이 필요한 특징들이 CycleGAN 프레임워크에서 무감독 방법으로 스스로 학습되는 방법으로, 언어 확장이 용이한 방법이다. 언어학적 분석에서 드러난 주요한 변이들 간의 우선순위는 Auxiliary Classifier CycleGAN 구조에서 모델링하는 것을 제안하였다. 이 방법은 기존의 CycleGAN에 지식을 접목시켜 피드백 음성을 생성함과 동시에 해당 피드백이 어떤 유형의 오류인지 분류하는 문제를 수행한다. 이는 도메인 지식이 교정 피드백 생성 단계까지 유지되고 통제가 가능하다는 장점이 있다는 데에 그 의의가 있다. 본 연구에서 제안한 방법을 평가하기 위해서 27개의 모국어를 갖는 217명의 유의미 어휘 발화 65,100개로 피드백 자동 생성 모델을 훈련하고, 개선 여부 및 정도에 대한 지각 평가를 수행하였다. 제안된 방법을 사용하였을 때 학습자 본인의 목소리를 유지한 채 교정된 발음으로 변환하는 것이 가능하며, 전통적인 방법인 음높이 동기식 중첩가산 (Pitch-Synchronous Overlap-and-Add) 알고리즘을 사용하는 방법에 비해 상대 개선률 16.67%이 확인되었다.Chapter 1. Introduction 1 1.1. Motivation 1 1.1.1. An Overview of CAPT Systems 3 1.1.2. Survey of existing Korean CAPT Systems 5 1.2. Problem Statement 7 1.3. Thesis Structure 7 Chapter 2. Pronunciation Analysis of Korean Produced by Chinese 9 2.1. Comparison between Korean and Chinese 11 2.1.1. Phonetic and Syllable Structure Comparisons 11 2.1.2. Phonological Comparisons 14 2.2. Related Works 16 2.3. Proposed Analysis Method 19 2.3.1. Corpus 19 2.3.2. Transcribers and Agreement Rates 22 2.4. Salient Pronunciation Variations 22 2.4.1. Segmental Variation Patterns 22 2.4.1.1. Discussions 25 2.4.2. Phonological Variation Patterns 26 2.4.1.2. Discussions 27 2.5. Summary 29 Chapter 3. Correlation Analysis of Pronunciation Variations and Human Evaluation 30 3.1. Related Works 31 3.1.1. Criteria used in L2 Speech 31 3.1.2. Criteria used in L2 Korean Speech 32 3.2. Proposed Human Evaluation Method 36 3.2.1. Reading Prompt Design 36 3.2.2. Evaluation Criteria Design 37 3.2.3. Raters and Agreement Rates 40 3.3. Linguistic Factors Affecting L2 Korean Accentedness 41 3.3.1. Pearsons Correlation Analysis 41 3.3.2. Discussions 42 3.3.3. Implications for Automatic Feedback Generation 44 3.4. Summary 45 Chapter 4. Corrective Feedback Generation for CAPT 46 4.1. Related Works 46 4.1.1. Prosody Transplantation 47 4.1.2. Recent Speech Conversion Methods 49 4.1.3. Evaluation of Corrective Feedback 50 4.2. Proposed Method: Corrective Feedback as a Style Transfer 51 4.2.1. Speech Analysis at Spectral Domain 53 4.2.2. Self-imitative Learning 55 4.2.3. An Analogy: CAPT System and GAN Architecture 57 4.3. Generative Adversarial Networks 59 4.3.1. Conditional GAN 61 4.3.2. CycleGAN 62 4.4. Experiment 63 4.4.1. Corpus 64 4.4.2. Baseline Implementation 65 4.4.3. Adversarial Training Implementation 65 4.4.4. Spectrogram-to-Spectrogram Training 66 4.5. Results and Evaluation 69 4.5.1. Spectrogram Generation Results 69 4.5.2. Perceptual Evaluation 70 4.5.3. Discussions 72 4.6. Summary 74 Chapter 5. Integration of Linguistic Knowledge in an Auxiliary Classifier CycleGAN for Feedback Generation 75 5.1. Linguistic Class Selection 75 5.2. Auxiliary Classifier CycleGAN Design 77 5.3. Experiment and Results 80 5.3.1. Corpus 80 5.3.2. Feature Annotations 81 5.3.3. Experiment Setup 81 5.3.4. Results 82 5.4. Summary 84 Chapter 6. Conclusion 86 6.1. Thesis Results 86 6.2. Thesis Contributions 88 6.3. Recommendations for Future Work 89 Bibliography 91 Appendix 107 Abstract in Korean 117 Acknowledgments 120Docto

Listener Background in L2 Speech Evaluation

Listeners are integral parts of second language (L2) oral performance assessment. However, evaluation of listeners is susceptible to listener background variables and biases. These variables and preexisting biases distort native speaker (NS) listeners’ perceptions of non-native speakers’ (NNSs) speech performance and contribute errors into their oral performance assessment. Among listener background variables, listeners’ first language status, the amount of exposure to different English varieties, listeners’ educational background, prior language teaching experience, NNSs’ linguistic stereotyping, and listener attitude have been investigated in the literature and assumed to exert sizable amount of variation in speakers’ oral proficiency true scores. To minimize listeners’ bias in the assessment context, listeners are provided with intensive training programs in which they are trained how to rate NNSs’ speech more objectively utilizing scoring rubrics. To mediate listeners’ bias in social contexts, the literature has provided strands of evidence in favor of structured intergroup contact programs, which are inoculations particularly devised to improve NSs’ attitude, thereby making them more receptive to NNSs’ English varieties. To enhance L2 listeners’ self-efficacy and foster their autonomy, L2 instructors are encouraged to emphasize explicit instruction of listening strategies