Tapabrata Mondal


2026

Spontaneous speech in multilingual communities such as India frequently combines code-switching (CS) and disfluencies, yet existing Bengali–English and Hindi–English speech corpora largely consist of fluent or scripted utterances. This limits their suitability for developing and evaluating automatic speech recognition (ASR) systems intended for real conversational settings, particularly in micro-resource scenarios. We introduce BEHE-CMDisfl, a synthetic speech corpus that explicitly integrates disfluency phenomena within Bengali–English and Hindi–English code-mixed (CM) utterances. The textual content was generated using prompting strategies with large language models (LLMs) to encourage controlled switching and varied disfluency patterns, including filled pauses, repetitions, and restarts. The utterances were subsequently synthesized using Indic Parler text-to-speech (TTS) system. To demonstrate usability, we establish a reproducible GMM–HMM baseline for Bengali–English ASR using Kaldi on a 1.3-hour subset of the corpus. In our experiments, improvements were mainly observed after ensuring consistency in the pronunciation lexicon and applying phonetic normalization, with the best setup reaching a word error rate (WER) of 37.74%. A closer look at the decoded transcripts suggests that filled pauses and repetitions are not automatically collapsed, but appear in the output, indicating that the disfluency cues present in the synthetic speech are captured during recognition.
Spontaneous speech in multilingual communities often involves rapid code-mixing (CM) and natural disfluencies, yet such patterns are rarely reflected in available training data for under-resourced languages. This gap limits the development of robust automatic speech recognition (ASR) systems. To address this, we introduce BEHE-CMDisfl, a fully synthetic Bengali–English and Hindi–English disfluent code-mixed speech corpus generated through a controlled Large Language Model (LLM) and Text-to-Speech (TTS) pipeline. The dataset explicitly incorporates conversational phenomena such as filled pauses, repetitions, and restarts. We evaluate its usefulness under two ASR settings. In a micro-resource scenario (∼1.3 hours), a GMM-HMM Kaldi baseline achieved a 37.74% Word Error Rate (WER) after phonetic normalization to reduce transliteration inconsistencies, and successfully retained disfluency markers in decoding. We also examined adaptation of a modern foundation model. In zero-shot testing, openai/whisper-small failed on the code-mixed speech due to severe hallucinations and looping behavior. After applying parameter-efficient fine-tuning (LoRA) for 1,000 steps, the model stabilized, reduced insertion errors, captured rapid language switching more reliably, and achieved a WER of 21.37%. These findings show that synthetic data combined with efficient fine-tuning offers a practical path for ASR development in complex low-resource disfluent CM settings.

2025

This work explores the intersection of code-mixing and disfluency in bilingual speech and text, with a focus on understanding how large language models (LLMs) handle code-mixed disfluent utterances. One of the primary objectives is to explore LLMs’ ability to generate code-mixed disfluent sentences and to address the lack of high-quality code-mixed disfluent corpora, particularly for Indic languages. We aim to compare the performance of LLM-based approaches with traditional disfluency detection methods and to develop novel metrics for quantitatively assessing disfluency phenomena. Additionally, we investigate the relationship between code-mixing and disfluency, exploring how factors such as switching frequency and direction influence the occurrence of disfluencies. By analyzing these intriguing dynamics, we seek to gain a deeper understanding of the mutual influence between code-mixing and disfluency in multilingual speech.
We propose a compact hybrid quantum–classical extension of OpenAI’s Whisper in which classical components are replaced by Quantum Convolutional Neural Networks (QCNN), Quantum LSTMs (QLSTM), and optional Quantum Adaptive Self-Attention (QASA). Log-mel spectrograms are angle encoded and processed by QCNN kernels, whose outputs feed a Transformer encoder, while QLSTM-based decoding introduces quantum-enhanced temporal modeling. The design incorporates pretrained acoustic embeddings and is constrained to NISQ-feasible circuit depths and qubit counts. Although this work is primarily architectural, we provide a fully specified, reproducible evaluation plan using Speech Commands, LibriSpeech, and Common Voice, along with strong classical baselines and measurable hypotheses for assessing noise robustness, efficiency, and parameter sparsity. To our knowledge, this is the first hardware-aware, module-wise quantum replacement framework for Whisper.
This paper presents the submission of the Jadavpur University Computer Science and Engineering Natural Language Processing (JU-CSENLP) Laboratory to the International Conference on Spoken Language Translation (IWSLT) 2025 Indic track, addressing the speech-to-text translation task in both English-to-Indic (Bengali, Hindi, Tamil) and Indic-to-English directions. To tackle the challenges posed by low resource Indian languages, we adopt a cascaded approach leveraging state-of-the-art pre-trained models. For English-to-Indic translation, we utilize OpenAI’s Whisper model for Automatic Speech Recognition (ASR), followed by the Meta’s No Language Left Behind (NLLB)-200-distilled-600M model finetuned for Machine Translation (MT). For the reverse direction, we employ the AI4Bharat’s IndicConformer model for ASR and IndicTrans2 finetuned for MT. Our models are fine-tuned on the provided benchmark dataset to better handle the linguistic diversity and domain-specific variations inherent in the data. Evaluation results demonstrate that our cascaded systems achieve competitive performance, with notable BLEU and chrF++ scores across all language pairs. Our findings highlight the effectiveness of combining robust ASR and MT components in a cascaded pipeline, particularly for low-resource and morphologically rich Indian languages.

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