LeBenchmark: A Reproducible Framework for Assessing Self-Supervised Representation Learning from Speech

Self-Supervised Learning (SSL) using huge unlabeled data has been successfully explored for image and natural language processing. Recent works also investigated SSL from speech. They were notably successful to improve performance on downstream tasks such as automatic speech recognition (ASR). While these works suggest it is possible to reduce dependence on labeled data for building efficient speech systems, their evaluation was mostly made on ASR and using multiple and heterogeneous experimental settings (most of them for English). This questions the objective comparison of SSL approaches and the evaluation of their impact on building speech systems. In this paper, we propose LeBenchmark: a reproducible framework for assessing SSL from speech. It not only includes ASR (high and low resource) tasks but also spoken language understanding, speech translation and emotion recognition. We also focus on speech technologies in a language different than English: French. SSL models of different sizes are trained from carefully sourced and documented datasets. Experiments show that SSL is beneficial for most but not all tasks which confirms the need for exhaustive and reliable benchmarks to evaluate its real impact. LeBenchmark is shared with the scientific community for reproducible research in SSL from speech.Comment: Will be presented at Interspeech 202

Continuous Emotion Prediction from Speech: Modelling Ambiguity in Emotion

There is growing interest in emotion research to model perceived emotion labelled as intensities along the affect dimensions such as arousal and valence. These labels are typically obtained from multiple annotators who would have their individualistic perceptions of emotional speech. Consequently, emotion prediction models that incorporate variation in individual perceptions as ambiguity in the emotional state would be more realistic. This thesis develops the modelling framework necessary to achieve continuous prediction of ambiguous emotional states from speech. Besides, emotion labels, feature space distribution and encoding are an integral part of the prediction system. The first part of this thesis examines the limitations of current low-level feature distributions and their minimalistic statistical descriptions. Specifically, front-end paralinguistic acoustic features are reflective of speech production mechanisms. However, discriminatively learnt features have frequently outperformed acoustic features in emotion prediction tasks, but provide no insights into the physical significance of these features. One of the contributions of this thesis is the development of a framework that can modify the acoustic feature representation based on emotion label information. Another investigation in this thesis indicates that emotion perception is language-dependent and in turn, helped develop a framework for cross-language emotion prediction. Furthermore, this investigation supported the hypothesis that emotion perception is highly individualistic and is better modelled as a distribution rather than a point estimate to encode information about the ambiguity in the perceived emotion. Following this observation, the thesis proposes measures to quantify the appropriateness of distribution types in modelling ambiguity in dimensional emotion labels which are then employed to compare well-known bounded parametric distributions. These analyses led to the conclusion that the beta distribution was the most appropriate parametric model of ambiguity in emotion labels. Finally, the thesis focuses on developing a deep learning framework for continuous emotion prediction as a temporal series of beta distributions, examining various parameterizations of the beta distributions as well as loss functions. Furthermore, distribution over the parameter spaces is examined and priors from kernel density estimation are employed to shape the posteriors over the parameter space which significantly improved valence ambiguity predictions. The proposed frameworks and methods have been extensively evaluated on multiple state of-the-art databases and the results demonstrate both the viability of predicting ambiguous emotion states and the validity of the proposed systems

Robust Methods for the Automatic Quantification and Prediction of Affect in Spoken Interactions

Emotional expression plays a key role in interactions as it communicates the necessary context needed for understanding the behaviors and intentions of individuals. Therefore, a speech-based Artificial Intelligence (AI) system that can recognize and interpret emotional expression has many potential applications with measurable impact to a variety of areas, including human-computer interaction (HCI) and healthcare. However, there are several factors that make speech emotion recognition (SER) a difficult task; these factors include: variability in speech data, variability in emotion annotations, and data sparsity. This dissertation explores methodologies for improving the robustness of the automatic recognition of emotional expression from speech by addressing the impacts of these factors on various aspects of the SER system pipeline. For addressing speech data variability in SER, we propose modeling techniques that improve SER performance by leveraging short-term dynamical properties of speech. Furthermore, we demonstrate how data augmentation improves SER robustness to speaker variations. Lastly, we discover that we can make more accurate predictions of emotion by considering the fine-grained interactions between the acoustic and lexical components of speech. For addressing the variability in emotion annotations, we propose SER modeling techniques that account for the behaviors of annotators (i.e., annotators' reaction delay) to improve time-continuous SER robustness. For addressing data sparsity, we investigate two methods that enable us to learn robust embeddings, which highlight the differences that exist between neutral speech and emotionally expressive speech, without requiring emotion annotations. In the first method, we demonstrate how emotionally charged vocal expressions change speaker characteristics as captured by embeddings extracted from a speaker identification model, and we propose the use of these embeddings in SER applications. In the second method, we propose a framework for learning emotion embeddings using audio-textual data that is not annotated for emotion. The unification of the methods and results presented in this thesis helps enable the development of more robust SER systems, making key advancements toward an interactive speech-based AI system that is capable of recognizing and interpreting human behaviors.PHDComputer Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/166106/1/aldeneh_1.pd

Deep Learning for Environmentally Robust Speech Recognition: An Overview of Recent Developments

Eliminating the negative effect of non-stationary environmental noise is a long-standing research topic for automatic speech recognition that stills remains an important challenge. Data-driven supervised approaches, including ones based on deep neural networks, have recently emerged as potential alternatives to traditional unsupervised approaches and with sufficient training, can alleviate the shortcomings of the unsupervised methods in various real-life acoustic environments. In this light, we review recently developed, representative deep learning approaches for tackling non-stationary additive and convolutional degradation of speech with the aim of providing guidelines for those involved in the development of environmentally robust speech recognition systems. We separately discuss single- and multi-channel techniques developed for the front-end and back-end of speech recognition systems, as well as joint front-end and back-end training frameworks

Speech-based recognition of self-reported and observed emotion in a dimensional space

The differences between self-reported and observed emotion have only marginally been investigated in the context of speech-based automatic emotion recognition. We address this issue by comparing self-reported emotion ratings to observed emotion ratings and look at how differences between these two types of ratings affect the development and performance of automatic emotion recognizers developed with these ratings. A dimensional approach to emotion modeling is adopted: the ratings are based on continuous arousal and valence scales. We describe the TNO-Gaming Corpus that contains spontaneous vocal and facial expressions elicited via a multiplayer videogame and that includes emotion annotations obtained via self-report and observation by outside observers. Comparisons show that there are discrepancies between self-reported and observed emotion ratings which are also reflected in the performance of the emotion recognizers developed. Using Support Vector Regression in combination with acoustic and textual features, recognizers of arousal and valence are developed that can predict points in a 2-dimensional arousal-valence space. The results of these recognizers show that the self-reported emotion is much harder to recognize than the observed emotion, and that averaging ratings from multiple observers improves performance