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RESEARCH PAPER / 2025-12-16

Joint Multimodal Contrastive Learning for Robust Spoken Term Detection and Keyword Spotting

Ramesh Gundluru, Shubham Gupta, Sri Rama Murty K

Indian Institute of Technology Hyderabad · arXiv

Affiliations: Indian Institute of Technology Hyderabad

Abstract

Acoustic Word Embeddings (AWEs) improve the efficiency of speech retrieval tasks such as Spoken Term Detection (STD) and Keyword Spotting (KWS). However, existing approaches suffer from limitations, including unimodal supervision, disjoint optimization of audio-audio and audio-text alignment, and the need for task-specific models. To address these shortcomings, we propose a joint multimodal contrastive learning framework that unifies both acoustic and cross-modal supervision in a shared embedding space. Our approach simultaneously optimizes: (i) audio-text contrastive learning, inspired by the CLAP loss, to align audio and text representations and (ii) audio-audio contrastive learning, via Deep Word Discrimination (DWD) loss, to enhance intra-class compactness and inter-class separation. The proposed method outperforms existing AWE baselines on word discrimination task while flexibly supporting both STD and KWS. To our knowledge, this is the first comprehensive approach of its kind.

The following analysis is generated by AI and may contain errors. It is separate from the authors’ abstract and is not peer review.

Research summary

The paper introduces a novel joint multimodal contrastive learning framework for robust spoken term detection and keyword spotting, demonstrating significant improvements over existing methods. The comprehensive methodology and rigorous experimental evaluation highlight its potential impact on the field of audio processing and machine learning.

Methodology

The proposed joint multimodal contrastive learning framework effectively integrates audio and text modalities into a unified embedding space, addressing significant limitations of existing Acoustic Word Embedding (AWE) methods. The dual optimization of audio-text and audio-audio contrastive learning is innovative, leveraging the strengths of both modalities while enhancing intra-class compactness and inter-class separation. The methodology is well-structured, with clear explanations of the loss functions and training regime, although further details on hyperparameter tuning could enhance clarity.

Results & evaluation

The experiments are robust, utilizing the LibriSpeech corpus to evaluate the proposed model against multiple baselines. The performance metrics, including Average Precision (AP) and Equal Error Rates (EER), provide a comprehensive view of the model's capabilities in both Spoken Term Detection (STD) and Keyword Spotting (KWS). The results demonstrate consistent improvements over existing methods, particularly in challenging conditions, which underscores the effectiveness of the proposed approach.

Reproducibility

The authors emphasize reproducibility by releasing a standardized evaluation framework and the trial generation recipe alongside their codebase. This commitment to transparency is commendable and facilitates further research in the field. However, more detailed documentation on the training process and hyperparameter settings would be beneficial for full reproducibility.

Limitations

While the paper presents a significant advancement, it does not extensively discuss the potential computational costs associated with the proposed model, particularly in real-time applications. Additionally, the reliance on the LibriSpeech dataset may limit the generalizability of the findings to other languages or dialects.

Broader impact

The proposed framework has the potential to significantly improve spoken content retrieval systems, making them more robust to variations in speaker and background noise. This advancement could enhance accessibility in various applications, such as voice-activated systems and automated transcription services, thereby contributing to the broader adoption of speech technologies. The paper introduces a novel joint multimodal contrastive learning framework for robust spoken term detection and keyword spotting, demonstrating significant improvements over existing methods. The comprehensive methodology and rigorous experimental evaluation highlight its potential impact on the field of audio processing and machine learning.

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