Spoken Language Understanding Models Research Articles

Position-aware Interactive Attention Network for multi-intent spoken language understanding

Spoken Language Understanding (SLU) is a crucial component of task-oriented dialog systems. In recent years, there has been increasing attention on multi-intent SLU due to its relevance to complex real-world applications. Most existing joint models only utilize multi-intent information to guide the slot filling, with only a small number of models achieving bidirectional interaction. Additionally, unlike traditional single-intent SLU, multi-intent SLU is scope-dependent, where each intent in a sentence has its specific dependency range. However, current bidirectional joint models often employ a pipeline approach to implement interaction between the two sub-tasks, which fails to fully leverage the semantic information between them and can lead to error propagation. Moreover, attention-based multi-intent joint models do not adequately model the positional relationships between words, resulting in suboptimal overall performance. In this paper, we propose a novel multi-intent SLU model called Position-aware Interactive Attention Network (PIAN), which consists of interactive attention and rotary position embedding. The aim of PIAN is to fully exploit the correlation between the two sub-tasks and capturing the positional dependencies between words. This facilitates mutual guidance and enhancement between the two sub-tasks. Additionally, to address the issue of uncoordinated slot problem generated by traditional slot filling decoders, we employ an MCRF slot filling decoder to constrain the slot labels. We evaluate our model on two public multi-intent SLU datasets, and the experimental results demonstrate that our model achieves state-of-the-art performance on key metrics. Code for this paper is publicly available at https://github.com/puhahahahahaha/SLU_with_Co_PRoE.

Benefits of pre-trained mono- and cross-lingual speech representations for spoken language understanding of Dutch dysarthric speech

With the rise of deep learning, spoken language understanding (SLU) for command-and-control applications such as a voice-controlled virtual assistant can offer reliable hands-free operation to physically disabled individuals. However, due to data scarcity, it is still a challenge to process dysarthric speech. Pre-training (part of) the SLU model with supervised automatic speech recognition (ASR) targets or with self-supervised learning (SSL) may help to overcome a lack of data, but no research has shown which pre-training strategy performs better for SLU on dysarthric speech and to which extent the SLU task benefits from knowledge transfer from pre-training with dysarthric acoustic tasks. This work aims to compare different mono- or cross-lingual pre-training (supervised and unsupervised) methodologies and quantitatively investigates the benefits of pre-training for SLU tasks on Dutch dysarthric speech. The designed SLU systems consist of a pre-trained speech representations encoder and a SLU decoder to map encoded features to intents. Four types of pre-trained encoders, a mono-lingual time-delay neural network (TDNN) acoustic model, a mono-lingual transformer acoustic model, a cross-lingual transformer acoustic model (Whisper), and a cross-lingual SSL Wav2Vec2.0 model (XLSR-53), are evaluated complemented with three types of SLU decoders: non-negative matrix factorization (NMF), capsule networks, and long short-term memory (LSTM) networks. The acoustic analysis of the four pre-trained encoders are tested on Dutch dysarthric home-automation data with word error rate (WER) results to investigate the correlations of the dysarthric acoustic task (ASR) and the semantic task (SLU). By introducing the intelligibility score (IS) as a metric of the impairment severity, this paper further quantitatively analyzes dysarthria-severity-dependent models for SLU tasks.

Adaptive Global-Local Context Fusion for Multi-Turn Spoken Language Understanding

Recent years have seen significant advances in multi-turn Spoken Language Understanding (SLU), where dialogue contexts are used to guide intent classification and slot filling. However, how to selectively incorporate dialogue contexts, such as previous utterances and dialogue acts, into multi-turn SLU still remains a substantial challenge. In this work, we propose a novel contextual SLU model for multi-turn intent classification and slot filling tasks. We introduce an adaptive global-local context fusion mechanism to selectively integrate dialogue contexts into our model. The local context fusion aligns each dialogue context using multi-head attention, while the global context fusion measures overall context contribution to intent classification and slot filling tasks. Experiments show that on two benchmark datasets, our model achieves absolute F1 score improvements of 2.73% and 2.57% for the slot filling task on Sim-R and Sim M datasets, respectively. Additional experiments on a large-scale, de-identified, in-house dataset further verify the measurable accuracy gains of our proposed model.

Text Is No More Enough! A Benchmark for Profile-Based Spoken Language Understanding

Current researches on spoken language understanding (SLU) heavily are limited to a simple setting: the plain text-based SLU that takes the user utterance as input and generates its corresponding semantic frames (e.g., intent and slots). Unfortunately, such a simple setting may fail to work in complex real-world scenarios when an utterance is semantically ambiguous, which cannot be achieved by the text-based SLU models. In this paper, we first introduce a new and important task, Profile-based Spoken Language Understanding (ProSLU), which requires the model that not only relies on the plain text but also the supporting profile information to predict the correct intents and slots. To this end, we further introduce a large-scale human-annotated Chinese dataset with over 5K utterances and their corresponding supporting profile information (Knowledge Graph (KG), User Profile (UP), Context Awareness (CA)). In addition, we evaluate several state-of-the-art baseline models and explore a multi-level knowledge adapter to effectively incorporate profile information. Experimental results reveal that all existing text-based SLU models fail to work when the utterances are semantically ambiguous and our proposed framework can effectively fuse the supporting information for sentence-level intent detection and token-level slot filling. Finally, we summarize key challenges and provide new points for future directions, which hopes to facilitate the research.

ARoBERT: An ASR Robust Pre-Trained Language Model for Spoken Language Understanding

Spoken Language Understanding (SLU) aims to interpret the meanings of human speeches in order to support various human-machine interaction systems. A key technique for SLU is Automatic Speech Recognition (ASR), which transcribes speech signals into text contents. As the output texts of modern ASR systems unavoidably contain errors, mainstream SLU models either trained or tested on texts transcribed by ASR systems would not be sufficiently error robust. We present ARoBERT, an ASR Robust BERT model, which can be fine-tuned to solve a variety of SLU tasks with noisy inputs. To guarantee the robustness of ARoBERT, during pretraining, we decrease the fluctuations of language representations when some parts of the input texts are replaced by homophones or synophones. Specifically, we propose two novel self-supervised pre-training tasks for ARoBERT, namely Phonetically-aware Masked Language Modeling (PMLM) and ASR Model-adaptive Masked Language Modeling (AMMLM). The PMLM task explicitly fuses the knowledge of word phonetic similarities into the pre-training process, which forces homophones and synophones to share similar representations. In AMMLM, a data-driven algorithm is further introduced to mine typical ASR errors such that ARoBERT can tolerate ASR model errors. In the experiments, we evaluate ARoBERT over multiple datasets. The results show the superiority of ARoBERT, which consistently outperforms strong baselines. We have also shown that ARoBERT outperforms state-of-the-arts on a public benchmark. Currently, ARoBERT has been deployed in an online production system with significant improvements.

Data Augmentation for Spoken Language Understanding via Joint Variational Generation

Data scarcity is one of the main obstacles of domain adaptation in spoken language understanding (SLU) due to the high cost of creating manually tagged SLU datasets. Recent works in neural text generative models, particularly latent variable models such as variational autoencoder (VAE), have shown promising results in regards to generating plausible and natural sentences. In this paper, we propose a novel generative architecture which leverages the generative power of latent variable models to jointly synthesize fully annotated utterances. Our experiments show that existing SLU models trained on the additional synthetic examples achieve performance gains. Our approach not only helps alleviate the data scarcity issue in the SLU task for many datasets but also indiscriminately improves language understanding performances for various SLU models, supported by extensive experiments and rigorous statistical testing.

Active learning process for spoken dialog systems

A large amount of human labor is required to transcribe and annotate a training corpus that is needed to create and update models for automatic speech recognition (ASR) and spoken language understanding (SLU). Active learning enables a reduction in the amount of transcribed and annotated data required to train ASR and SLU models. In one aspect of the present invention, an active learning ASR process and active learning SLU process are coupled, thereby enabling further efficiencies to be gained relative to a process that maintains an isolation of data in both the ASR and SLU domains.

A multi-stage approach for Thai spoken language understanding

This article investigates a novel multi-stage approach for spoken language understanding (SLU), with an application to a pioneering Thai spoken dialogue system in a hotel reservation domain. Given an input word string, the system determines a goal and concept-values by three-stage processing; concept extraction, goal identification, and concept-value recognition. The concept extraction utilizes weighted finite state transducers (WFST) to extract concepts from the word string. Given the extracted concepts, a goal of the utterance is identified using a pattern classifier. Within a particular goal, the necessary concept-values are recognized from the WFST outputs produced in the concept extraction stage. A new logical N-gram model, which strategically combines the conventional N-gram parser with a regular grammar, is evaluated for concept extraction and concept-value recognition. Several classifiers are optimized and compared for goal identification. An advantage of the proposed SLU model is that it can be trained by a partially annotated corpus, where only the relevant keywords and the goal of each training utterance are required. Although the proposed model is evaluated only on the Thai hotel reservation system, the SLU itself is general and it is expected to be applicable for other languages once training data is available.