Research
Mutual Correlation Attentive Factors in Dyadic Fusion Networks for Speech Emotion Recognition
Emotion recognition in dyadic communication is challenging because: 1. Extracting informative modality-specific representations requires disparate feature extractor designs due to the heterogenous input data formats. 2. How to effectively and efficiently fuse unimodal features and learn associations between dyadic utterances are critical to the model generalization in actual scenario. 3. Disagreeing annotations prevent previous approaches from precisely predicting emotions in context. To address the above issues, we propose an efficient dyadic fusion network that only relies on an attention mechanism to select representative vectors, fuse modality-specific features, and learn the sequence information. Our approach has three distinct characteristics: 1. Instead of using a recurrent neural network to extract temporal associations as in most previous research, we introduce multiple sub-view attention layers to compute the relevant dependencies among sequential utterances; this significantly improves model efficiency. 2. To improve fusion performance, we design a learnable mutual correlation factor inside each attention layer to compute associations across different modalities. 3. To overcome the label disagreement issue, we embed the labels from all annotators into a k-dimensional vector and transform the categorical problem into a regression problem; this method provides more accurate annotation information and fully uses the entire dataset. We evaluate the proposed model on two published multimodal emotion recognition datasets: IEMOCAP and MELD. Our model significantly outperforms previous state-of-the-art research by 3.8%-7.5% accuracy, using a more efficient model. [paper]
Multimodal Attention Network for Trauma Activity Recognition
Trauma activity recognition aims to detect, recognize, and predict the activities (or tasks) during trauma resuscitation. Previous work has mainly focused on using various sensor data including image, RFID, and vital signals to generate the trauma event log. However, spoken language and environmental sound, which contain rich communication and contextual information necessary for trauma team cooperation, are still largely ignored. In this paper, we propose a multimodal attention network (MAN) that uses both verbal transcripts and environmental audio stream as input; the model extracts textual and acoustic features using a multi-level multi-head attention module, and forms a final shared representation for trauma activity classification. We evaluated the proposed architecture on 75 actual trauma resuscitation cases collected from a hospital. We achieved 71.8% accuracy with 0.702 F1 score, demonstrating that our proposed architecture is useful and efficient. These results also show that using spoken language and environmental audio indeed helps identify hard-to-recognize activities, compared to previous approaches. We also provide a detailed analysis of the performance and generalization of the proposed multimodal attention network. [paper coming soon]
Human Conversation Analysis Using Attentive Multimodal Networks with Hierarchical Encoder-Decoder
Human conversation analysis is challenging because meaning can be expressed through words, intonation, even body language and facial expression. We introduce a hierarchical encoder-decoder structure with attention mechanism for conversation analysis. The hierarchical encoder learns word-level features from video, audio, and text data that are then formulated into conversation-level features. The corresponding hierarchical decoder is able to predict different attributes at given time instances. To integrate multiple sensory inputs, we introduce a novel fusion strategy with modality attention. We evaluated our system on published emotion recognition, sentiment analysis, and speaker trait analysis datasets. Our system outperformed previous state-of-the-art approaches on classification and regressions tasks using three datasets. We also outperformed previous approaches at generalization tests on two commonly used datasets. We achieved comparable performance using the proposed model instead of multiple individual models for co-existing labels. In addition, the easily-visualized modality and temporal attention demonstrate that the proposed attention mechanisms help feature selection and improve model interpretability. [paper]
Multimodal Affective Analysis Using Hierarchical Attention Strategy with Word-Level Alignment
Multimodal affective computing, learning to recognize and interpret human affects and subjective information from multiple data sources, is still challenge because: (i) it is hard to extract informative features to represent human affects from heterogeneous inputs; (ii) current fusion strategies only fuse different modalities at abstract level, ignoring time-dependent interactions between modalities. Addressing such issues, we introduce a hierarchical multimodal architecture with attention and word-level fusion to classify utterance-level sentiment and emotion from text and audio data. We propose three fusion strategies: horizontal fusion, vertical fusion, and fine-tuning attention fusion. These methods allow easy synchronization between modalities, taking advantage of the attentive associations across text and audio, creating a shared high-level representation. Our introduced model outperforms the state-of-the-art approaches on published datasets and we demonstrated that our model is able to visualize and interpret the synchronized attention over modalities. [paper]
Hybrid Attention based Multimodal Network for Spoken Language Classification
We examine the utility of linguistic content and vocal characteristics for multimodal deep learning in human spoken language understanding. We present a deep multimodal network with both feature attention and modality attention to classify utterance-level speech data. The proposed hybrid attention architecture helps the system focus on learning informative representations for both modality-specific feature extraction and model fusion. The experimental results show that our system achieves state-of-the-art or competitive results on three published multimodal datasets. We also demonstrated the effectiveness and generalization of our system on a medical speech dataset from an actual trauma scenario. Furthermore, we provided a detailed comparison and analysis of traditional approaches and deep learning methods on both feature extraction and fusion. [paper]
Deep Multimodal Learning for Emotion recognition in Spoken language
We present a novel deep multimodal framework to predict human emotions based on sentence-level spoken language. Our architecture has two distinctive characteristics. First, it extracts the high-level features from both text and audio via a hybrid deep multimodal structure, which considers the spatial information from text, temporal information from audio, and high-level associations from low-level handcrafted features. Second, we fuse all features by using a three-layer deep neural network to learn the correlations across modalities and train the feature extraction and fusion modules together, allowing optimal global fine-tuning of the entire structure. We evaluated the proposed framework on the IEMOCAP dataset. Our result shows promising performance, achieving 60.4% in weighted accuracy for five emotion categories. [paper]
Language-Based Process Phase Detection in the Trauma Resuscitation
Process phase detection has been widely used in surgical process modeling (SPM) to track process progression. We present a long-short term memory (LSTM) deep learning model to predict trauma resuscitation phases using verbal communication logs. We first use an LSTM to extract the sentence meaning representations, and then sequentially feed them into another LSTM to extract the meaning of a sentence group within a time window. This information is ultimately used for phase prediction. We used 24 manually-transcribed trauma resuscitation cases to train, and the remaining 6 cases to test our model. We achieved 79.12% accuracy, and showed performance advantages over existing visual-audio systems for critical phases of the process. In addition to language information, we evaluated a multimodal phase prediction structure that also uses audio input. We finally identified the challenges of substituting manual transcription with automatic speech recognition in trauma resuscitation. [paper]
Speech Intention Classification with Multimodal Deep Learning
We present a novel multimodal deep learning structure that automatically extracts features from textual-acoustic data for sentence-level speech classification. Textual and acoustic features were first extracted using two independent convolutional neural network structures, then combined into a joint representation, and finally fed into a decision softmax layer. We tested the proposed model in an actual medical setting, using speech recording and its transcribed log. Our model achieved 83.10% average accuracy in detecting 6 different intentions. We also found that our model using automatically extracted features for intention classification outperformed existing models that use manufactured features. [paper]