Yannick Estève


2022

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The Spoken Language Understanding MEDIA Benchmark Dataset in the Era of Deep Learning: data updates, training and evaluation tools
Gaëlle Laperrière | Valentin Pelloin | Antoine Caubrière | Salima Mdhaffar | Nathalie Camelin | Sahar Ghannay | Bassam Jabaian | Yannick Estève
Proceedings of the Thirteenth Language Resources and Evaluation Conference

With the emergence of neural end-to-end approaches for spoken language understanding (SLU), a growing number of studies have been presented during these last three years on this topic. The major part of these works addresses the spoken language understanding domain through a simple task like speech intent detection. In this context, new benchmark datasets have also been produced and shared with the community related to this task. In this paper, we focus on the French MEDIA SLU dataset, distributed since 2005 and used as a benchmark dataset for a large number of research works. This dataset has been shown as being the most challenging one among those accessible to the research community. Distributed by ELRA, this corpus is free for academic research since 2019. Unfortunately, the MEDIA dataset is not really used beyond the French research community. To facilitate its use, a complete recipe, including data preparation, training and evaluation scripts, has been built and integrated to SpeechBrain, an already popular open-source and all-in-one conversational AI toolkit based on PyTorch. This recipe is presented in this paper. In addition, based on the feedback of some researchers who have worked on this dataset for several years, some corrections have been brought to the initial manual annotation: the new version of the data will also be integrated into the ELRA catalogue, as the original one. More, a significant amount of data collected during the construction of the MEDIA corpus in the 2000s was never used until now: we present the first results reached on this subset — also included in the MEDIA SpeechBrain recipe — , that will be used for now as the MEDIA test2. Last, we discuss evaluation issues.

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Speech Resources in the Tamasheq Language
Marcely Zanon Boito | Fethi Bougares | Florentin Barbier | Souhir Gahbiche | Loïc Barrault | Mickael Rouvier | Yannick Estève
Proceedings of the Thirteenth Language Resources and Evaluation Conference

In this paper we present two datasets for Tamasheq, a developing language mainly spoken in Mali and Niger. These two datasets were made available for the IWSLT 2022 low-resource speech translation track, and they consist of collections of radio recordings from daily broadcast news in Niger (Studio Kalangou) and Mali (Studio Tamani). We share (i) a massive amount of unlabeled audio data (671 hours) in five languages: French from Niger, Fulfulde, Hausa, Tamasheq and Zarma, and (ii) a smaller 17 hours parallel corpus of audio recordings in Tamasheq, with utterance-level translations in the French language. All this data is shared under the Creative Commons BY-NC-ND 3.0 license. We hope these resources will inspire the speech community to develop and benchmark models using the Tamasheq language.

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Impact Analysis of the Use of Speech and Language Models Pretrained by Self-Supersivion for Spoken Language Understanding
Salima Mdhaffar | Valentin Pelloin | Antoine Caubrière | Gaëlle Laperriere | Sahar Ghannay | Bassam Jabaian | Nathalie Camelin | Yannick Estève
Proceedings of the Thirteenth Language Resources and Evaluation Conference

Pretrained models through self-supervised learning have been recently introduced for both acoustic and language modeling. Applied to spoken language understanding tasks, these models have shown their great potential by improving the state-of-the-art performances on challenging benchmark datasets. In this paper, we present an error analysis reached by the use of such models on the French MEDIA benchmark dataset, known as being one of the most challenging benchmarks for the slot filling task among all the benchmarks accessible to the entire research community. One year ago, the state-of-art system reached a Concept Error Rate (CER) of 13.6% through the use of a end-to-end neural architecture. Some months later, a cascade approach based on the sequential use of a fine-tuned wav2vec2.0 model and a fine-tuned BERT model reaches a CER of 11.2%. This significant improvement raises questions about the type of errors that remain difficult to treat, but also about those that have been corrected using these models pre-trained through self-supervision learning on a large amount of data. This study brings some answers in order to better understand the limits of such models and open new perspectives to continue improving the performance.

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Actes de la 29e Conférence sur le Traitement Automatique des Langues Naturelles. Volume 1 : conférence principale
Yannick Estève | Tania Jiménez | Titouan Parcollet | Marcely Zanon Boito
Actes de la 29e Conférence sur le Traitement Automatique des Langues Naturelles. Volume 1 : conférence principale

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Actes de la 29e Conférence sur le Traitement Automatique des Langues Naturelles. Volume 2 : 24e Rencontres Etudiants Chercheurs en Informatique pour le TAL (RECITAL)
Yannick Estève | Tania Jiménez | Titouan Parcollet | Marcely Zanon Boito
Actes de la 29e Conférence sur le Traitement Automatique des Langues Naturelles. Volume 2 : 24e Rencontres Etudiants Chercheurs en Informatique pour le TAL (RECITAL)

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Actes de la 29e Conférence sur le Traitement Automatique des Langues Naturelles. Volume 3 : Démonstrations
Yannick Estève | Tania Jiménez | Titouan Parcollet | Marcely Zanon Boito
Actes de la 29e Conférence sur le Traitement Automatique des Langues Naturelles. Volume 3 : Démonstrations

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Findings of the IWSLT 2022 Evaluation Campaign
Antonios Anastasopoulos | Loïc Barrault | Luisa Bentivogli | Marcely Zanon Boito | Ondřej Bojar | Roldano Cattoni | Anna Currey | Georgiana Dinu | Kevin Duh | Maha Elbayad | Clara Emmanuel | Yannick Estève | Marcello Federico | Christian Federmann | Souhir Gahbiche | Hongyu Gong | Roman Grundkiewicz | Barry Haddow | Benjamin Hsu | Dávid Javorský | Vĕra Kloudová | Surafel Lakew | Xutai Ma | Prashant Mathur | Paul McNamee | Kenton Murray | Maria Nǎdejde | Satoshi Nakamura | Matteo Negri | Jan Niehues | Xing Niu | John Ortega | Juan Pino | Elizabeth Salesky | Jiatong Shi | Matthias Sperber | Sebastian Stüker | Katsuhito Sudoh | Marco Turchi | Yogesh Virkar | Alexander Waibel | Changhan Wang | Shinji Watanabe
Proceedings of the 19th International Conference on Spoken Language Translation (IWSLT 2022)

The evaluation campaign of the 19th International Conference on Spoken Language Translation featured eight shared tasks: (i) Simultaneous speech translation, (ii) Offline speech translation, (iii) Speech to speech translation, (iv) Low-resource speech translation, (v) Multilingual speech translation, (vi) Dialect speech translation, (vii) Formality control for speech translation, (viii) Isometric speech translation. A total of 27 teams participated in at least one of the shared tasks. This paper details, for each shared task, the purpose of the task, the data that were released, the evaluation metrics that were applied, the submissions that were received and the results that were achieved.

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ON-TRAC Consortium Systems for the IWSLT 2022 Dialect and Low-resource Speech Translation Tasks
Marcely Zanon Boito | John Ortega | Hugo Riguidel | Antoine Laurent | Loïc Barrault | Fethi Bougares | Firas Chaabani | Ha Nguyen | Florentin Barbier | Souhir Gahbiche | Yannick Estève
Proceedings of the 19th International Conference on Spoken Language Translation (IWSLT 2022)

This paper describes the ON-TRAC Consortium translation systems developed for two challenge tracks featured in the Evaluation Campaign of IWSLT 2022: low-resource and dialect speech translation. For the Tunisian Arabic-English dataset (low-resource and dialect tracks), we build an end-to-end model as our joint primary submission, and compare it against cascaded models that leverage a large fine-tuned wav2vec 2.0 model for ASR. Our results show that in our settings pipeline approaches are still very competitive, and that with the use of transfer learning, they can outperform end-to-end models for speech translation (ST). For the Tamasheq-French dataset (low-resource track) our primary submission leverages intermediate representations from a wav2vec 2.0 model trained on 234 hours of Tamasheq audio, while our contrastive model uses a French phonetic transcription of the Tamasheq audio as input in a Conformer speech translation architecture jointly trained on automatic speech recognition, ST and machine translation losses. Our results highlight that self-supervised models trained on smaller sets of target data are more effective to low-resource end-to-end ST fine-tuning, compared to large off-the-shelf models. Results also illustrate that even approximate phonetic transcriptions can improve ST scores.

2021

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ON-TRAC’ systems for the IWSLT 2021 low-resource speech translation and multilingual speech translation shared tasks
Hang Le | Florentin Barbier | Ha Nguyen | Natalia Tomashenko | Salima Mdhaffar | Souhir Gabiche Gahbiche | Benjamin Lecouteux | Didier Schwab | Yannick Estève
Proceedings of the 18th International Conference on Spoken Language Translation (IWSLT 2021)

This paper describes the ON-TRAC Consortium translation systems developed for two challenge tracks featured in the Evaluation Campaign of IWSLT 2021, low-resource speech translation and multilingual speech translation. The ON-TRAC Consortium is composed of researchers from three French academic laboratories and an industrial partner: LIA (Avignon Université), LIG (Université Grenoble Alpes), LIUM (Le Mans Université), and researchers from Airbus. A pipeline approach was explored for the low-resource speech translation task, using a hybrid HMM/TDNN automatic speech recognition system fed by wav2vec features, coupled to an NMT system. For the multilingual speech translation task, we investigated the us of a dual-decoder Transformer that jointly transcribes and translates an input speech. This model was trained in order to translate from multiple source languages to multiple target ones.

2020

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ON-TRAC Consortium for End-to-End and Simultaneous Speech Translation Challenge Tasks at IWSLT 2020
Maha Elbayad | Ha Nguyen | Fethi Bougares | Natalia Tomashenko | Antoine Caubrière | Benjamin Lecouteux | Yannick Estève | Laurent Besacier
Proceedings of the 17th International Conference on Spoken Language Translation

This paper describes the ON-TRAC Consortium translation systems developed for two challenge tracks featured in the Evaluation Campaign of IWSLT 2020, offline speech translation and simultaneous speech translation. ON-TRAC Consortium is composed of researchers from three French academic laboratories: LIA (Avignon Université), LIG (Université Grenoble Alpes), and LIUM (Le Mans Université). Attention-based encoder-decoder models, trained end-to-end, were used for our submissions to the offline speech translation track. Our contributions focused on data augmentation and ensembling of multiple models. In the simultaneous speech translation track, we build on Transformer-based wait-k models for the text-to-text subtask. For speech-to-text simultaneous translation, we attach a wait-k MT system to a hybrid ASR system. We propose an algorithm to control the latency of the ASR+MT cascade and achieve a good latency-quality trade-off on both subtasks.

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Où en sommes-nous dans la reconnaissance des entités nommées structurées à partir de la parole ? (Where are we in Named Entity Recognition from speech ?)
Antoine Caubrière | Sophie Rosset | Yannick Estève | Antoine Laurent | Emmanuel Morin
Actes de la 6e conférence conjointe Journées d'Études sur la Parole (JEP, 33e édition), Traitement Automatique des Langues Naturelles (TALN, 27e édition), Rencontre des Étudiants Chercheurs en Informatique pour le Traitement Automatique des Langues (RÉCITAL, 22e édition). Volume 1 : Journées d'Études sur la Parole

La reconnaissance des entités nommées (REN) à partir de la parole est traditionnellement effectuée par l’intermédiaire d’une chaîne de composants, exploitant un système de reconnaissance de la parole (RAP), puis un système de REN appliqué sur les transcriptions automatiques. Les dernières données disponibles pour la REN structurées à partir de la parole en français proviennent de la campagne d’évaluation ETAPE en 2012. Depuis la publication des résultats, des améliorations majeures ont été réalisées pour les systèmes de REN et de RAP. Notamment avec le développement des systèmes neuronaux. De plus, certains travaux montrent l’intérêt des approches de bout en bout pour la tâche de REN dans la parole. Nous proposons une étude des améliorations en RAP et REN dans le cadre d’une chaîne de composants, ainsi qu’une nouvelle approche en trois étapes. Nous explorons aussi les capacités d’une approche bout en bout pour la REN structurées. Enfin, nous comparons ces deux types d’approches à l’état de l’art de la campagne ETAPE. Nos résultats montrent l’intérêt de l’approche bout en bout, qui reste toutefois en deçà d’une chaîne de composants entièrement mise à jour.

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Prédiction continue de la satisfaction et de la frustration dans des conversations de centre d’appels (AlloSat : A New Call Center French Corpus for Affect Analysis)
Manon Macary | Marie Tahon | Yannick Estève | Anthony Rousseau
Actes de la 6e conférence conjointe Journées d'Études sur la Parole (JEP, 33e édition), Traitement Automatique des Langues Naturelles (TALN, 27e édition), Rencontre des Étudiants Chercheurs en Informatique pour le Traitement Automatique des Langues (RÉCITAL, 22e édition). Volume 1 : Journées d'Études sur la Parole

Nous présentons un nouveau corpus, nommé AlloSat, composé de conversations en français extraites de centre d’appels, annotées de façon continue en frustration et satisfaction. Dans le contexte des centres d’appels, une conversation vise généralement à résoudre la demande de l’appelant. Ce corpus a été mis en place afin de développer de nouveaux systèmes capables de modéliser l’aspect continu de l’information sémantique et para-linguistique au niveau conversationnel. Nous nous concentrons sur le niveau para-linguistique, plus précisément sur l’expression des émotions. À notre connaissance, la plupart des corpus émotionnels contiennent des annotations en catégories discrètes ou dans des dimensions continues telles que l’activation ou la valence. Nous supposons que ces dimensions ne sont pas suffisamment liées à notre contexte. Pour résoudre ce problème, nous proposons un corpus permettant une connaissance en temps réel de l’axe frustration/satisfaction. AlloSat regroupe 303 conversations pour un total d’environ 37 heures d’audio, toutes enregistrées dans des environnements réels, collectées par Allo-Media (une société spécialisée dans l’analyse automatique d’appels). Les premières expériences de classification montrent que l’évolution de l’axe frustration/satisfaction peut être prédite automatiquement par conversation.

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AlloSat: A New Call Center French Corpus for Satisfaction and Frustration Analysis
Manon Macary | Marie Tahon | Yannick Estève | Anthony Rousseau
Proceedings of the Twelfth Language Resources and Evaluation Conference

We present a new corpus, named AlloSat, composed of real-life call center conversations in French that is continuously annotated in frustration and satisfaction. This corpus has been set up to develop new systems able to model the continuous aspect of semantic and paralinguistic information at the conversation level. The present work focuses on the paralinguistic level, more precisely on the expression of emotions. In the call center industry, the conversation usually aims at solving the caller’s request. As far as we know, most emotional databases contain static annotations in discrete categories or in dimensions such as activation or valence. We hypothesize that these dimensions are not task-related enough. Moreover, static annotations do not enable to explore the temporal evolution of emotional states. To solve this issue, we propose a corpus with a rich annotation scheme enabling a real-time investigation of the axis frustration / satisfaction. AlloSat regroups 303 conversations with a total of approximately 37 hours of audio, all recorded in real-life environments collected by Allo-Media (an intelligent call tracking company). First regression experiments, with audio features, show that the evolution of frustration / satisfaction axis can be retrieved automatically at the conversation level.

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A Multimodal Educational Corpus of Oral Courses: Annotation, Analysis and Case Study
Salima Mdhaffar | Yannick Estève | Antoine Laurent | Nicolas Hernandez | Richard Dufour | Delphine Charlet | Geraldine Damnati | Solen Quiniou | Nathalie Camelin
Proceedings of the Twelfth Language Resources and Evaluation Conference

This corpus is part of the PASTEL (Performing Automated Speech Transcription for Enhancing Learning) project aiming to explore the potential of synchronous speech transcription and application in specific teaching situations. It includes 10 hours of different lectures, manually transcribed and segmented. The main interest of this corpus lies in its multimodal aspect: in addition to speech, the courses were filmed and the written presentation supports (slides) are made available. The dataset may then serve researches in multiple fields, from speech and language to image and video processing. The dataset will be freely available to the research community. In this paper, we first describe in details the annotation protocol, including a detailed analysis of the manually labeled data. Then, we propose some possible use cases of the corpus with baseline results. The use cases concern scientific fields from both speech and text processing, with language model adaptation, thematic segmentation and transcription to slide alignment.

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Where are we in Named Entity Recognition from Speech?
Antoine Caubrière | Sophie Rosset | Yannick Estève | Antoine Laurent | Emmanuel Morin
Proceedings of the Twelfth Language Resources and Evaluation Conference

Named entity recognition (NER) from speech is usually made through a pipeline process that consists in (i) processing audio using an automatic speech recognition system (ASR) and (ii) applying a NER to the ASR outputs. The latest data available for named entity extraction from speech in French were produced during the ETAPE evaluation campaign in 2012. Since the publication of ETAPE’s campaign results, major improvements were done on NER and ASR systems, especially with the development of neural approaches for both of these components. In addition, recent studies have shown the capability of End-to-End (E2E) approach for NER / SLU tasks. In this paper, we propose a study of the improvements made in speech recognition and named entity recognition for pipeline approaches. For this type of systems, we propose an original 3-pass approach. We also explore the capability of an E2E system to do structured NER. Finally, we compare the performances of ETAPE’s systems (state-of-the-art systems in 2012) with the performances obtained using current technologies. The results show the interest of the E2E approach, which however remains below an updated pipeline approach.

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Toward Qualitative Evaluation of Embeddings for Arabic Sentiment Analysis
Amira Barhoumi | Nathalie Camelin | Chafik Aloulou | Yannick Estève | Lamia Hadrich Belguith
Proceedings of the Twelfth Language Resources and Evaluation Conference

In this paper, we propose several protocols to evaluate specific embeddings for Arabic sentiment analysis (SA) task. In fact, Arabic language is characterized by its agglutination and morphological richness contributing to great sparsity that could affect embedding quality. This work presents a study that compares embeddings based on words and lemmas in SA frame. We propose first to study the evolution of embedding models trained with different types of corpora (polar and non polar) and explore the variation between embeddings by observing the sentiment stability of neighbors in embedding spaces. Then, we evaluate embeddings with a neural architecture based on convolutional neural network (CNN). We make available our pre-trained embeddings to Arabic NLP research community with free to use. We provide also for free resources used to evaluate our embeddings. Experiments are done on the Large Arabic-Book Reviews (LABR) corpus in binary (positive/negative) classification frame. Our best result reaches 91.9%, that is higher than the best previous published one (91.5%).

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Align then Summarize: Automatic Alignment Methods for Summarization Corpus Creation
Paul Tardy | David Janiszek | Yannick Estève | Vincent Nguyen
Proceedings of the Twelfth Language Resources and Evaluation Conference

Summarizing texts is not a straightforward task. Before even considering text summarization, one should determine what kind of summary is expected. How much should the information be compressed? Is it relevant to reformulate or should the summary stick to the original phrasing? State-of-the-art on automatic text summarization mostly revolves around news articles. We suggest that considering a wider variety of tasks would lead to an improvement in the field, in terms of generalization and robustness. We explore meeting summarization: generating reports from automatic transcriptions. Our work consists in segmenting and aligning transcriptions with respect to reports, to get a suitable dataset for neural summarization. Using a bootstrapping approach, we provide pre-alignments that are corrected by human annotators, making a validation set against which we evaluate automatic models. This consistently reduces annotators’ efforts by providing iteratively better pre-alignment and maximizes the corpus size by using annotations from our automatic alignment models. Evaluation is conducted on publicmeetings, a novel corpus of aligned public meetings. We report automatic alignment and summarization performances on this corpus and show that automatic alignment is relevant for data annotation since it leads to large improvement of almost +4 on all ROUGE scores on the summarization task.

2019

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Curriculum d’apprentissage : reconnaissance d’entités nommées pour l’extraction de concepts sémantiques (Curriculum learning : named entity recognition for semantic concept extraction)
Antoine Caubrière | Natalia Tomashenko | Yannick Estève | Antoine Laurent | Emmanuel Morin
Actes de la Conférence sur le Traitement Automatique des Langues Naturelles (TALN) PFIA 2019. Volume I : Articles longs

Dans cet article, nous présentons une approche de bout en bout d’extraction de concepts sémantiques de la parole. En particulier, nous mettons en avant l’apport d’une chaîne d’apprentissage successif pilotée par une stratégie de curriculum d’apprentissage. Dans la chaîne d’apprentissage mise en place, nous exploitons des données françaises annotées en entités nommées que nous supposons être des concepts plus génériques que les concepts sémantiques liés à une application informatique spécifique. Dans cette étude, il s’agit d’extraire des concepts sémantiques dans le cadre de la tâche MEDIA. Pour renforcer le système proposé, nous exploitons aussi des stratégies d’augmentation de données, un modèle de langage 5-gramme, ainsi qu’un mode étoile aidant le système à se concentrer sur les concepts et leurs valeurs lors de l’apprentissage. Les résultats montrent un intérêt à l’utilisation des données d’entités nommées, permettant un gain relatif allant jusqu’à 6,5 %.

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Apport de l’adaptation automatique des modèles de langage pour la reconnaissance de la parole: évaluation qualitative extrinsèque dans un contexte de traitement de cours magistraux (Contribution of automatic adaptation of language models for speech recognition : extrinsic qualitative evaluation in a context of educational courses)
Salima Mdhaffar | Yannick Estève | Nicolas Hernandez | Antoine Laurent | Solen Quiniou
Actes de la Conférence sur le Traitement Automatique des Langues Naturelles (TALN) PFIA 2019. Volume II : Articles courts

Malgré les faiblesses connues de cette métrique, les performances de différents systèmes de reconnaissance automatique de la parole sont généralement comparées à l’aide du taux d’erreur sur les mots. Les transcriptions automatiques de ces systèmes sont de plus en plus exploitables et utilisées dans des systèmes complexes de traitement automatique du langage naturel, par exemple pour la traduction automatique, l’indexation, la recherche documentaire... Des études récentes ont proposé des métriques permettant de comparer la qualité des transcriptions automatiques de différents systèmes en fonction de la tâche visée. Dans cette étude nous souhaitons mesurer, qualitativement, l’apport de l’adaptation automatique des modèles de langage au domaine visé par un cours magistral. Les transcriptions du discours de l’enseignant peuvent servir de support à la navigation dans le document vidéo du cours magistral ou permettre l’enrichissement de son contenu pédagogique. C’est à-travers le prisme de ces deux tâches que nous évaluons l’apport de l’adaptation du modèle de langage. Les expériences ont été menées sur un corpus de cours magistraux et montrent combien le taux d’erreur sur les mots est une métrique insuffisante qui masque les apports effectifs de l’adaptation des modèles de langage.

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Plongements lexicaux spécifiques à la langue arabe : application à l’analyse d’opinions (Arabic-specific embedddings : application in Sentiment Analysis)
Amira Barhoumi | Nathalie Camelin | Chafik Aloulou | Yannick Estève | Lamia Hadrich Belguith
Actes de la Conférence sur le Traitement Automatique des Langues Naturelles (TALN) PFIA 2019. Volume II : Articles courts

Nous nous intéressons, dans cet article, à la tâche d’analyse d’opinions en arabe. Nous étudions la spécificité de la langue arabe pour la détection de polarité. Nous nous focalisons ici sur les caractéristiques d’agglutination et de richesse morphologique de cette langue. Nous avons particulièrement étudié différentes représentations d’unité lexicale : token, lemme et light stemme. Nous avons construit et testé des espaces continus de ces différentes représentations lexicales. Nous avons mesuré l’apport de tels types de representations vectorielles dans notre cadre spécifique. Les performances du réseau CNN montrent un gain significatif de 2% par rapport à l’état de l’art.

2018

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FrNewsLink : a corpus linking TV Broadcast News Segments and Press Articles
Nathalie Camelin | Géraldine Damnati | Abdessalam Bouchekif | Anais Landeau | Delphine Charlet | Yannick Estève
Proceedings of the Eleventh International Conference on Language Resources and Evaluation (LREC 2018)

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Simulating ASR errors for training SLU systems
Edwin Simonnet | Sahar Ghannay | Nathalie Camelin | Yannick Estève
Proceedings of the Eleventh International Conference on Language Resources and Evaluation (LREC 2018)

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Evaluation of Feature-Space Speaker Adaptation for End-to-End Acoustic Models
Natalia Tomashenko | Yannick Estève
Proceedings of the Eleventh International Conference on Language Resources and Evaluation (LREC 2018)

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Des représentations continues de mots pour l’analyse d’opinions en arabe: une étude qualitative (Word embeddings for Arabic sentiment analysis : a qualitative study)
Amira Barhoumi | Nathalie Camelin | Yannick Estève
Actes de la Conférence TALN. Volume 1 - Articles longs, articles courts de TALN

Nous nous intéressons, dans cet article, à la détection d’opinions dans la langue arabe. Ces dernières années, l’utilisation de l’apprentissage profond a amélioré des performances de nombreux systèmes automatiques dans une grande variété de domaines (analyse d’images, reconnaissance de la parole, traduction automatique, . . .) et également celui de l’analyse d’opinions en anglais. Ainsi, nous avons étudié l’apport de deux architectures (CNN et LSTM) dans notre cadre spécifique. Nous avons également testé et comparé plusieurs types de représentations continues de mots (embeddings) disponibles en langue arabe, qui ont permis d’obtenir de bons résultats. Nous avons analysé les erreurs de notre système et la pertinence de ces embeddings. Cette analyse mène à plusieurs perspectives intéressantes de travail, au sujet notamment de la constitution automatique de ressources expert et d’une construction pertinente des embeddings spécifiques à la tâche d’analyse d’opinions.

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Le corpus PASTEL pour le traitement automatique de cours magistraux (PASTEL corpus for automatic processing of lectures)
Salima Mdhaffar | Antoine Laurent | Yannick Estève
Actes de la Conférence TALN. Volume 1 - Articles longs, articles courts de TALN

Le projet PASTEL étudie l’acceptabilité et l’utilisabilité des transcriptions automatiques dans le cadre d’enseignements magistraux. Il s’agit d’outiller les apprenants pour enrichir de manière synchrone et automatique les informations auxquelles ils peuvent avoir accès durant la séance. Cet enrichissement s’appuie sur des traitements automatiques du langage naturel effectués sur les transcriptions automatiques. Nous présentons dans cet article un travail portant sur l’annotation d’enregistrements de cours magistraux enregistrés dans le cadre du projet CominOpenCourseware. Ces annotations visent à effectuer des expériences de transcription automatique, segmentation thématique, appariement automatique en temps réel avec des ressources externes... Ce corpus comprend plus de neuf heures de parole annotées. Nous présentons également des expériences préliminaires réalisées pour évaluer l’adaptation automatique de notre système de reconnaissance de la parole.

2017

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Sentiment Analysis of Tunisian Dialects: Linguistic Ressources and Experiments
Salima Medhaffar | Fethi Bougares | Yannick Estève | Lamia Hadrich-Belguith
Proceedings of the Third Arabic Natural Language Processing Workshop

Dialectal Arabic (DA) is significantly different from the Arabic language taught in schools and used in written communication and formal speech (broadcast news, religion, politics, etc.). There are many existing researches in the field of Arabic language Sentiment Analysis (SA); however, they are generally restricted to Modern Standard Arabic (MSA) or some dialects of economic or political interest. In this paper we are interested in the SA of the Tunisian Dialect. We utilize Machine Learning techniques to determine the polarity of comments written in Tunisian Dialect. First, we evaluate the SA systems performances with models trained using freely available MSA and Multi-dialectal data sets. We then collect and annotate a Tunisian Dialect corpus of 17.000 comments from Facebook. This corpus allows us a significant accuracy improvement compared to the best model trained on other Arabic dialects or MSA data. We believe that this first freely available corpus will be valuable to researchers working in the field of Tunisian Sentiment Analysis and similar areas.

2016

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Word Embedding Evaluation and Combination
Sahar Ghannay | Benoit Favre | Yannick Estève | Nathalie Camelin
Proceedings of the Tenth International Conference on Language Resources and Evaluation (LREC'16)

Word embeddings have been successfully used in several natural language processing tasks (NLP) and speech processing. Different approaches have been introduced to calculate word embeddings through neural networks. In the literature, many studies focused on word embedding evaluation, but for our knowledge, there are still some gaps. This paper presents a study focusing on a rigorous comparison of the performances of different kinds of word embeddings. These performances are evaluated on different NLP and linguistic tasks, while all the word embeddings are estimated on the same training data using the same vocabulary, the same number of dimensions, and other similar characteristics. The evaluation results reported in this paper match those in the literature, since they point out that the improvements achieved by a word embedding in one task are not consistently observed across all tasks. For that reason, this paper investigates and evaluates approaches to combine word embeddings in order to take advantage of their complementarity, and to look for the effective word embeddings that can achieve good performances on all tasks. As a conclusion, this paper provides new perceptions of intrinsic qualities of the famous word embedding families, which can be different from the ones provided by works previously published in the scientific literature.

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Enhancing The RATP-DECODA Corpus With Linguistic Annotations For Performing A Large Range Of NLP Tasks
Carole Lailler | Anaïs Landeau | Frédéric Béchet | Yannick Estève | Paul Deléglise
Proceedings of the Tenth International Conference on Language Resources and Evaluation (LREC'16)

In this article, we present the RATP-DECODA Corpus which is composed by a set of 67 hours of speech from telephone conversations of a Customer Care Service (CCS). This corpus is already available on line at http://sldr.org/sldr000847/fr in its first version. However, many enhancements have been made in order to allow the development of automatic techniques to transcript conversations and to capture their meaning. These enhancements fall into two categories: firstly, we have increased the size of the corpus with manual transcriptions from a new operational day; secondly we have added new linguistic annotations to the whole corpus (either manually or through an automatic processing) in order to perform various linguistic tasks from syntactic and semantic parsing to dialog act tagging and dialog summarization.

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Exploration de paramètres acoustiques dérivés de GMM pour l’adaptation non supervisée de modèles acoustiques à base de réseaux de neurones profonds (Exploring GMM-derived features for unsupervised adaptation of deep neural network acoustic models)
Natalia Tomashenko | Yuri Khokhlov | Anthony Larcher | Yannick Estève
Actes de la conférence conjointe JEP-TALN-RECITAL 2016. volume 1 : JEP

L’étude présentée dans cet article améliore une méthode récemment proposée pour l’adaptation de modèles acoustiques markoviens couplés à un réseau de neurones profond (DNN-HMM). Cette méthode d’adaptation utilise des paramètres acoustiques dérivés de mixtures de modèles Gaussiens (GMM-derived features, GMMD ). L’amélioration provient de l’emploi de scores et de mesures de confiance calculés à partir de graphes construits dans le cadre d’un algorithme d’adaptation conventionnel dit de maximum a posteriori (MAP). Une version modifiée de l’adaptation MAP est appliquée sur le modèle GMM auxiliaire utilisé dans une procédure d’apprentissage adaptatif au locuteur (speaker adaptative training, SAT) lors de l’apprentissage du DNN. Des expériences menées sur le corpus Wall Street Journal (WSJ0) montrent que la technique d’adaptation non supervisée proposée dans cet article permet une réduction relative de 8, 4% du taux d’erreurs sur les mots (WER), par rapport aux résultats obtenus avec des modèles DNN-HMM indépendants du locuteur utilisant des paramètres acoustiques plus conventionnels.

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Des Réseaux de Neurones avec Mécanisme d’Attention pour la Compréhension de la Parole (Exploring the use of Attention-Based Recurrent Neural Networks For Spoken Language Understanding )
Edwin Simonnet | Paul Deléglise | Nathalie Camelin | Yannick Estève
Actes de la conférence conjointe JEP-TALN-RECITAL 2016. volume 1 : JEP

L’étude porte sur l’apport d’un réseau de neurones récurrent (Recurrent Neural Network RNN) bidirectionnel encodeur/décodeur avec mécanisme d’attention pour une tâche de compréhension de la parole. Les premières expériences faites sur le corpus ATIS confirment la qualité du système RNN état de l’art utilisé pour cet article, en comparant les résultats obtenus à ceux récemment publiés dans la littérature. Des expériences supplémentaires montrent que les RNNs avec mécanisme d’attention obtiennent de meilleures performances que les RNNs récemment proposés pour la tâche d’étiquetage en concepts sémantiques. Sur le corpus MEDIA, un corpus français état de l’art pour la compréhension dédié à la réservation d’hôtel et aux informations touristiques, les expériences montrent qu’un RNN bidirectionnel atteint une f-mesure de 79,51 tandis que le même système intégrant le mécanisme d’attention permet d’atteindre une f-mesure de 80,27.

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Utilisation des représentations continues des mots et des paramètres prosodiques pour la détection d’erreurs dans les transcriptions automatiques de la parole (Combining continuous word representation and prosodic features for ASR error detection)
Sahar Ghannay | Yannick Estève | Nathalie Camelin | Camille Dutrey | Fabian Santiago | Martine Adda-Decker
Actes de la conférence conjointe JEP-TALN-RECITAL 2016. volume 1 : JEP

Récemment, l’utilisation des représentations continues de mots a connu beaucoup de succès dans plusieurs tâches de traitement du langage naturel. Dans cet article, nous proposons d’étudier leur utilisation dans une architecture neuronale pour la tâche de détection des erreurs au sein de transcriptions automatiques de la parole. Nous avons également expérimenté et évalué l’utilisation de paramètres prosodiques en suppléments des paramètres classiques (lexicaux, syntaxiques, . . .). La principale contribution de cet article porte sur la combinaison de différentes représentations continues de mots : plusieurs approches de combinaison sont proposées et évaluées afin de tirer profit de leurs complémentarités. Les expériences sont effectuées sur des transcriptions automatiques du corpus ETAPE générées par le système de reconnaissance automatique du LIUM. Les résultats obtenus sont meilleurs que ceux d’un système état de l’art basé sur les champs aléatoires conditionnels. Pour terminer, nous montrons que la mesure de confiance produite est particulièrement bien calibrée selon une évaluation en terme d’Entropie Croisée Normalisée (NCE).

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Evaluation of acoustic word embeddings
Sahar Ghannay | Yannick Estève | Nathalie Camelin | Paul Deleglise
Proceedings of the 1st Workshop on Evaluating Vector-Space Representations for NLP

2015

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Utilisation d’annotations sémantiques pour la validation automatique d’hypothèses dans des conversations téléphoniques
Carole Lailler | Yannick Estève | Renato De Mori | Mohamed Bouallègue | Mohamed Morchid
Actes de la 22e conférence sur le Traitement Automatique des Langues Naturelles. Articles courts

Les travaux présentés portent sur l’extraction automatique d’unités sémantiques et l’évaluation de leur pertinence pour des conversations téléphoniques. Le corpus utilisé est le corpus français DECODA. L’objectif de la tâche est de permettre l’étiquetage automatique en thème de chaque conversation. Compte tenu du caractère spontané de ce type de conversations et de la taille du corpus, nous proposons de recourir à une stratégie semi-supervisée fondée sur la construction d’une ontologie et d’un apprentissage actif simple : un annotateur humain analyse non seulement les listes d’unités sémantiques candidates menant au thème mais étudie également une petite quantité de conversations. La pertinence de la relation unissant les unités sémantiques conservées, le sous-thème issu de l’ontologie et le thème annoté est évaluée par un DNN, prenant en compte une représentation vectorielle du document. L’intégration des unités sémantiques retenues dans le processus de classification en thème améliore les performances.

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Segmentation et Titrage Automatique de Journaux Télévisés
Abdessalam Bouchekif | Géraldine Damnati | Nathalie Camelin | Yannick Estève | Delphine Charlet
Actes de la 22e conférence sur le Traitement Automatique des Langues Naturelles. Articles courts

Dans cet article, nous nous intéressons au titrage automatique des segments issus de la segmentation thématique de journaux télévisés. Nous proposons d’associer un segment à un article de presse écrite collecté le jour même de la diffusion du journal. La tâche consiste à apparier un segment à un article de presse à l’aide d’une mesure de similarité. Cette approche soulève plusieurs problèmes, comme la sélection des articles candidats, une bonne représentation du segment et des articles, le choix d’une mesure de similarité robuste aux imprécisions de la segmentation. Des expériences sont menées sur un corpus varié de journaux télévisés français collectés pendant une semaine, conjointement avec des articles aspirés à partir de la page d’accueil de Google Actualités. Nous introduisons une métrique d’évaluation reflétant la qualité de la segmentation, du titrage ainsi que la qualité conjointe de la segmentation et du titrage. L’approche donne de bonnes performances et se révèle robuste à la segmentation thématique.

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The LIUM ASR and SLT systems for IWSLT 2015
Mercedes Garcia Martínez | Loïc Barrault | Anthony Rousseau | Paul Deléglise | Yannick Estève
Proceedings of the 12th International Workshop on Spoken Language Translation: Evaluation Campaign

2014

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EUMSSI: a Platform for Multimodal Analysis and Recommendation using UIMA
Jens Grivolla | Maite Melero | Toni Badia | Cosmin Cabulea | Yannick Estève | Eelco Herder | Jean-Marc Odobez | Susanne Preuß | Raúl Marín
Proceedings of the Workshop on Open Infrastructures and Analysis Frameworks for HLT

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LIUM English-to-French spoken language translation system and the Vecsys/LIUM automatic speech recognition system for Italian language for IWSLT 2014
Anthony Rousseau | Loïc Barrault | Paul Deléglise | Yannick Estève | Holger Schwenk | Samir Bennacef | Armando Muscariello | Stephan Vanni
Proceedings of the 11th International Workshop on Spoken Language Translation: Evaluation Campaign

This paper describes the Spoken Language Translation system developed by the LIUM for the IWSLT 2014 evaluation campaign. We participated in two of the proposed tasks: (i) the Automatic Speech Recognition task (ASR) in two languages, Italian with the Vecsys company, and English alone, (ii) the English to French Spoken Language Translation task (SLT). We present the approaches and specificities found in our systems, as well as the results from the evaluation campaign.

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Enhancing the TED-LIUM Corpus with Selected Data for Language Modeling and More TED Talks
Anthony Rousseau | Paul Deléglise | Yannick Estève
Proceedings of the Ninth International Conference on Language Resources and Evaluation (LREC'14)

In this paper, we present improvements made to the TED-LIUM corpus we released in 2012. These enhancements fall into two categories. First, we describe how we filtered publicly available monolingual data and used it to estimate well-suited language models (LMs), using open-source tools. Then, we describe the process of selection we applied to new acoustic data from TED talks, providing additions to our previously released corpus. Finally, we report some experiments we made around these improvements.

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A Corpus and Phonetic Dictionary for Tunisian Arabic Speech Recognition
Abir Masmoudi | Mariem Ellouze Khmekhem | Yannick Estève | Lamia Hadrich Belguith | Nizar Habash
Proceedings of the Ninth International Conference on Language Resources and Evaluation (LREC'14)

In this paper we describe an effort to create a corpus and phonetic dictionary for Tunisian Arabic Automatic Speech Recognition (ASR). The corpus, named TARIC (Tunisian Arabic Railway Interaction Corpus) has a collection of audio recordings and transcriptions from dialogues in the Tunisian Railway Transport Network. The phonetic (or pronunciation) dictionary is an important ASR component that serves as an intermediary between acoustic models and language models in ASR systems. The method proposed in this paper, to automatically generate a phonetic dictionary, is rule based. For that reason, we define a set of pronunciation rules and a lexicon of exceptions. To determine the performance of our phonetic rules, we chose to evaluate our pronunciation dictionary on two types of corpora. The word error rate of word grapheme-to-phoneme mapping is around 9%.

2013

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Proceedings of TALN 2013 (Volume 1: Long Papers)
Emmanuel Morin | Yannick Estève
Proceedings of TALN 2013 (Volume 1: Long Papers)

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Proceedings of TALN 2013 (Volume 2: Short Papers)
Emmanuel Morin | Yannick Estève
Proceedings of TALN 2013 (Volume 2: Short Papers)

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Proceedings of TALN 2013 (Volume 3: System Demonstrations)
Emmanuel Morin | Yannick Estève
Proceedings of TALN 2013 (Volume 3: System Demonstrations)

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Proceedings of TALN 2013 (Volume 4: Invited Conferences)
Emmanuel Morin | Yannick Estève
Proceedings of TALN 2013 (Volume 4: Invited Conferences)

2012

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TED-LIUM: an Automatic Speech Recognition dedicated corpus
Anthony Rousseau | Paul Deléglise | Yannick Estève
Proceedings of the Eighth International Conference on Language Resources and Evaluation (LREC'12)

This paper presents the corpus developed by the LIUM for Automatic Speech Recognition (ASR), based on the TED Talks. This corpus was built during the IWSLT 2011 Evaluation Campaign, and is composed of 118 hours of speech with its accompanying automatically aligned transcripts. We describe the content of the corpus, how the data was collected and processed, how it will be publicly available and how we built an ASR system using this data leading to a WER score of 17.4 %. The official results we obtained at the IWSLT 2011 evaluation campaign are also discussed.

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Leveraging study of robustness and portability of spoken language understanding systems across languages and domains: the PORTMEDIA corpora
Fabrice Lefèvre | Djamel Mostefa | Laurent Besacier | Yannick Estève | Matthieu Quignard | Nathalie Camelin | Benoit Favre | Bassam Jabaian | Lina M. Rojas-Barahona
Proceedings of the Eighth International Conference on Language Resources and Evaluation (LREC'12)

The PORTMEDIA project is intended to develop new corpora for the evaluation of spoken language understanding systems. The newly collected data are in the field of human-machine dialogue systems for tourist information in French in line with the MEDIA corpus. Transcriptions and semantic annotations, obtained by low-cost procedures, are provided to allow a thorough evaluation of the systems' capabilities in terms of robustness and portability across languages and domains. A new test set with some adaptation data is prepared for each case: in Italian as an example of a new language, for ticket reservation as an example of a new domain. Finally the work is complemented by the proposition of a new high level semantic annotation scheme well-suited to dialogue data.

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Segmentation et Regroupement en Locuteurs d’une collection de documents audio (Cross-show speaker diarization) [in French]
Grégor Dupuy | Mickael Rouvier | Sylvain Meignier | Yannick Estève
Proceedings of the Joint Conference JEP-TALN-RECITAL 2012, volume 1: JEP

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Robustesse et portabilités multilingue et multi-domaines des systèmes de compréhension de la parole : les corpus du projet PortMedia (Robustness and portability of spoken language understanding systems among languages and domains : the PORTMEDIA project) [in French]
Fabrice Lefèvre | Djamel Mostefa | Laurent Besacier | Yannick Estève | Matthieu Quignard | Nathalie Camelin | Benoit Favre | Bassam Jabaian | Lina Rojas-Barahona
Proceedings of the Joint Conference JEP-TALN-RECITAL 2012, volume 1: JEP

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Avancées dans le domaine de la transcription automatique par décodage guidé (Improvements on driven decoding system combination) [in French]
Fethi Bougares | Yannick Estève | Paul Deléglise | Mickael Rouvier | Georges Linarès
Proceedings of the Joint Conference JEP-TALN-RECITAL 2012, volume 1: JEP

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Combinaison d’approches pour la reconnaissance du rôle des locuteurs (Combination of approaches for speaker role recognition) [in French]
Richard Dufour | Antoine Laurent | Yannick Estève
Proceedings of the Joint Conference JEP-TALN-RECITAL 2012, volume 1: JEP

2011

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LIUM’s systems for the IWSLT 2011 speech translation tasks
Anthony Rousseau | Fethi Bougares | Paul Deléglise | Holger Schwenk | Yannick Estève
Proceedings of the 8th International Workshop on Spoken Language Translation: Evaluation Campaign

This paper describes the three systems developed by the LIUM for the IWSLT 2011 evaluation campaign. We participated in three of the proposed tasks, namely the Automatic Speech Recognition task (ASR), the ASR system combination task (ASR_SC) and the Spoken Language Translation task (SLT), since these tasks are all related to speech translation. We present the approaches and specificities we developed on each task.

2010

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The EPAC Corpus: Manual and Automatic Annotations of Conversational Speech in French Broadcast News
Yannick Estève | Thierry Bazillon | Jean-Yves Antoine | Frédéric Béchet | Jérôme Farinas
Proceedings of the Seventh International Conference on Language Resources and Evaluation (LREC'10)

This paper presents the EPAC corpus which is composed by a set of 100 hours of conversational speech manually transcribed and by the outputs of automatic tools (automatic segmentation, transcription, POS tagging, etc.) applied on the entire French ESTER 1 audio corpus: this concerns about 1700 hours of audio recordings from radiophonic shows. This corpus was built during the EPAC project funded by the French Research Agency (ANR) from 2007 to 2010. This corpus increases significantly the amount of French manually transcribed audio recordings easily available and it is now included as a part of the ESTER 1 corpus in the ELRA catalog without additional cost. By providing a large set of automatic outputs of speech processing tools, the EPAC corpus should be useful to researchers who want to work on such data without having to develop and deal with such tools. These automatic annotations are various: segmentation and speaker diarization, one-best hypotheses from the LIUM automatic speech recognition system with confidence measures, but also word-lattices and confusion networks, named entities, part-of-speech tags, chunks, etc. The 100 hours of speech manually transcribed were split into three data sets in order to get an official training corpus, an official development corpus and an official test corpus. These data sets were used to develop and to evaluate some automatic tools which have been used to process the 1700 hours of audio recording. For example, on the EPAC test data set our ASR system yields a word error rate equals to 17.25%.

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LIUM’s statistical machine translation system for IWSLT 2010
Anthony Rousseau | Loïc Barrault | Paul Deléglise | Yannick Estève
Proceedings of the 7th International Workshop on Spoken Language Translation: Evaluation Campaign

This paper describes the two systems developed by the LIUM laboratory for the 2010 IWSLT evaluation campaign. We participated to the new English to French TALK task. We developed two systems, one for each evaluation condition, both being statistical phrase-based systems using the the Moses toolkit. Several approaches were investigated.

2009

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LIUM’s statistical machine translation system for IWSLT 2009
Holger Schwenk | Loïc Barrault | Yannick Estève | Patrik Lambert
Proceedings of the 6th International Workshop on Spoken Language Translation: Evaluation Campaign

This paper describes the systems developed by the LIUM laboratory for the 2009 IWSLT evaluation. We participated in the Arabic and Chinese to English BTEC tasks. We developed three different systems: a statistical phrase-based system using the Moses toolkit, an Statistical Post-Editing system and a hierarchical phrase-based system based on Joshua. A continuous space language model was deployed to improve the modeling of the target language. These systems are combined by a confusion network based approach.

2008

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Combined Systems for Automatic Phonetic Transcription of Proper Nouns
Antoine Laurent | Téva Merlin | Sylvain Meignier | Yannick Estève | Paul Deléglise
Proceedings of the Sixth International Conference on Language Resources and Evaluation (LREC'08)

Large vocabulary automatic speech recognition (ASR) technologies perform well in known, controlled contexts. However recognition of proper nouns is commonly considered as a difficult task. Accurate phonetic transcription of a proper noun is difficult to obtain, although it can be one of the most important resources for a recognition system. In this article, we propose methods of automatic phonetic transcription applied to proper nouns. The methods are based on combinations of the rule-based phonetic transcription generator LIA_PHON and an acoustic-phonetic decoding system. On the ESTER corpus, we observed that the combined systems obtain better results than our reference system (LIA_PHON). The WER (Word Error Rate) decreased on segments of speech containing proper nouns, without affecting negatively the results on the rest of the corpus. On the same corpus, the Proper Noun Error Rate (PNER, which is a WER computed on proper nouns only), decreased with our new system.

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Manual vs Assisted Transcription of Prepared and Spontaneous Speech
Thierry Bazillon | Yannick Estève | Daniel Luzzati
Proceedings of the Sixth International Conference on Language Resources and Evaluation (LREC'08)

Our paper focuses on the gain which can be achieved on human transcription of spontaneous and prepared speech, by using the assistance of an ASR system. This experiment has shown interesting results, first about the duration of the transcription task itself: even with the combination of prepared speech + ASR, an experimented annotator needs approximately 4 hours to transcribe 1 hours of audio data. Then, using an ASR system is mostly time-saving, although this gain is much more significant on prepared speech: assisted transcriptions are up to 4 times faster than manual ones. This ratio falls to 2 with spontaneous speech, because of ASR limits for these data. Detailed results reveal interesting correlations between the transcription task and phenomena such as Word Error Rate, telephonic or non-native speech turns, the number of fillers or propers nouns. The latter make spelling correction very time-consuming with prepared speech because of their frequency. As a consequence, watching for low averages of proper nouns may be a way to detect spontaneous speech.

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The LIUM Arabic/English statistical machine translation system for IWSLT 2008.
Holger Schwenk | Yannick Estève | Sadaf Abdul Rauf
Proceedings of the 5th International Workshop on Spoken Language Translation: Evaluation Campaign

This paper describes the system developed by the LIUM laboratory for the 2008 IWSLT evaluation. We only participated in the Arabic/English BTEC task. We developed a statistical phrase-based system using the Moses toolkit and SYSTRAN’s rule-based translation system to perform a morphological decomposition of the Arabic words. A continuous space language model was deployed to improve the modeling of the target language. Both approaches achieved significant improvements in the BLEU score. The system achieves a score of 49.4 on the test set of the 2008 IWSLT evaluation.

2006

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Automatic Detection of Well Recognized Words in Automatic Speech Transcriptions
Julie Mauclair | Yannick Estève | Simon Petit-Renaud | Paul Deléglise
Proceedings of the Fifth International Conference on Language Resources and Evaluation (LREC’06)

This work adresses the use of confidence measures for extracting well recognized words with very low error rate from automatically transcribed segments in a unsupervised way. We present and compare several confidence measures and propose a method to merge them into a new one. We study its capabilities on extracting correct recognized word-segments compared to the amount of rejected words. We apply this fusion measure to select audio segments composed of words with a high confidence score. These segments come from an automatic transcription of french broadcast news given by our speech recognition system based on the CMU Sphinx3.3 decoder. Injecting new data resulting from unsupervised treatments of raw audio recordings in the training corpus of acoustic models gives statistically significant improvement (95% confident interval) in terms of word error rate. Experiments have been carried out on the corpus used during ESTER, the french evaluation campaign.

2001

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Modèles de langage hiérarchiques pour les applications de dialogue en parole spontanée
Frédéric Béchet | Yannick Estève | Renato De Mori
Actes de la 8ème conférence sur le Traitement Automatique des Langues Naturelles. Posters

Le cadre de cette étude concerne les systèmes de dialogue via le téléphone entre un serveur de données et un utilisateur. Nous nous intéresserons au cas de dialogues non contraints où l’utilisateur à toute liberté pour formuler ses requêtes. Généralement, le module de Reconnaissance Automatique de la Parole (RAP) de tels serveurs utilise un seul Modèle de Langage (ML) de type bigramme ou trigramme pour modéliser l’ensemble des interventions possibles de l’utilisateur. Ces ML sont appris sur des corpus de phrases retranscrites à partir de sessions entre le serveur et plusieurs utilisateurs. Nous proposons dans cette étude une méthode de segmentation de corpus d’apprentissage de dialogue utilisant une stratégie mixte basée à la fois sur des connaissances explicites mais aussi sur l’optimisation d’un critère statistique. Nous montrons qu’un gain en terme de perplexité et de taux d’erreurs/mot peut être constaté en utilisant un ensemble de sous modèles de langage issus de la segmentation plutôt qu’un modèle unique appris sur l’ensemble du corpus.
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