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Bhuvana Ramabhadran

40 accepted papers

2025

Audio Diffusion with Large Language Models

ICASSP 2025accepted

In this paper, we explore an alternate approach to the popular method of using large language models (LLMs) as a second decoder for Automated Speech Recognition (ASR) and speech understanding tasks. We propose to employ diffusion networks to generate a correction signal that can be applied on the or…

Cited by 0SourceScholar
2025

Identifying and Mitigating Mismatched Language Code in Multilingual ASR

ICASSP 2025accepted

Multilingual speech recognition systems often use an input language code in order to prompt the transcription in the target language. However, the spoken language in the input audio may not always match the language code, as often prevalent in multilingual societies. This language mismatch can signi…

Cited by 0SourceScholar
2025

LegoSLM: Connecting LLM with Speech Encoder using CTC Posteriors

EMNLP 2025

Recently, large-scale pre-trained speech encoders and Large Language Models (LLMs) have been released, which show state-of-the-art performance on a range of spoken language processing tasks, including Automatic Speech Recognition (ASR). To effectively combine both models for better performance, cont

Cited by 0SourcePDFScholar
2025

Speech Re-Painting for Robust ASR

ICASSP 2025accepted

Synthetic speech is a useful source for augmentation of automatic speech recognition (ASR) systems, but there is a "sim-to-real" gap between synthetic and real speech that can limit generalization. The natural variability of real speech is essential to the training of robust ASR systems. While synth…

Cited by 0SourceScholar
2025

Weak-to-Strong Generalization in Speech Recognition

ICASSP 2025accepted

To surpass human-level accuracy, speech recognition models must go beyond relying solely on human labels. To this end, we must build stronger models from weaker supervisors and this is the main goal in weak-to-strong generalization (WSG). WSG methods normally incorporate additional information into…

Cited by 0SourceScholar
2024

Extending Multilingual Speech Synthesis to 100+ Languages without Transcribed Data

ICASSP 2024accepted

Collecting high-quality studio recordings of audio is challenging, which limits the language coverage of text-to-speech (TTS) systems. This paper proposes a framework for scaling a multilingual TTS model to 100+ languages using found data without supervision. The proposed framework combines speech-t…

Cited by 0SourceScholar
2023

JEIT: Joint End-to-End Model and Internal Language Model Training for Speech Recognition

ICASSP 2023accepted

We propose JEIT, a joint end-to-end (E2E) model and internal language model (ILM) training method to inject large-scale unpaired text into ILM during E2E training which improves rare-word speech recognition. With JEIT, the E2E model computes an E2E loss on audio-transcript pairs while its ILM estima…

Cited by 0SourceScholar
2023

Large-Scale Language Model Rescoring on Long-Form Data

ICASSP 2023accepted

In this work, we study the impact of Large-scale Language Models (LLM) on Automated Speech Recognition (ASR) of YouTube videos, which we use as a source for long-form ASR. We demonstrate up to 8% relative reduction in Word Error Eate (WER) on US English (en-us) and code-switched Indian English (en-i…

Cited by 0SourceScholar
2023

Modular Conformer Training for Flexible End-to-End ASR

ICASSP 2023accepted

The state-of-the-art conformer used in automatic speech recognition combines feed-forward, convolution and multi-headed self-attention layers in a single model that is trained end-to-end with a decoder network. While this end-to-end training is simple and beneficial for word error rate, it restricts…

Cited by 0SourceScholar
2023

Robust Knowledge Distillation from RNN-T Models with Noisy Training Labels Using Full-Sum Loss

ICASSP 2023accepted

This work studies knowledge distillation (KD) and addresses its constraints for recurrent neural network transducer (RNN-T) models. In hard distillation, a teacher model transcribes large amounts of unlabelled speech to train a student model. Soft distillation is another popular KD method that disti…

Cited by 0SourceScholar
2023

Understanding Shared Speech-Text Representations

ICASSP 2023accepted

Recently, a number of approaches to train speech models by incorporating text into end-to-end models have been developed, with Maestro advancing state-of-the-art automatic speech recognition (ASR) and Speech Translation (ST) performance. In this paper, we expand our understanding of the resulting sh…

Cited by 0SourceScholar
2023

Virtuoso: Massive Multilingual Speech-Text Joint Semi-Supervised Learning for Text-to-Speech

ICASSP 2023accepted

This paper proposes Virtuoso, a massively multilingual speech–text joint semi-supervised learning framework for text-to-speech synthesis (TTS) models. Existing multilingual TTS typically supports tens of languages, which are a small fraction of the thousands of languages in the world. One difficulty…

Cited by 0SourceScholar
2022

Multilingual Second-Pass Rescoring for Automatic Speech Recognition Systems

ICASSP 2022accepted

Second-pass rescoring is a well known technique to improve the performance of Automatic Speech Recognition (ASR) systems. Neural Oracle Search (NOS), which selects the most likely hypothesis from an N-best hypothesis list by integrating information from multiple sources, such as the input acoustic r…

Cited by 0SourceScholar
2022

Tts4pretrain 2.0: Advancing the use of Text and Speech in ASR Pretraining with Consistency and Contrastive Losses

ICASSP 2022accepted

An effective way to learn representations from untranscribed speech and unspoken text with linguistic/lexical representations derived from synthesized speech was introduced in tts4pretrain [1]. However, the representations learned from synthesized and real speech are likely to be different, potentia…

Cited by 0SourceScholar
2021

Convolutional Dropout and Wordpiece Augmentation for End-to-End Speech Recognition

ICASSP 2021accepted

Regularization and data augmentation are crucial to training end-to-end automatic speech recognition systems. Dropout is a popular regularization technique, which operates on each neuron independently by multiplying it with a Bernoulli random variable. We propose a generalization of dropout, called…

Cited by 0SourceScholar
2021

Extending Parrotron: An End-to-End, Speech Conversion and Speech Recognition Model for Atypical Speech

ICASSP 2021accepted

We present an extended Parrotron model: a single, end-to-end network that enables voice conversion and recognition simultaneously. Input spectrograms are transformed to output spectrograms in the voice of a predetermined target speaker while also generating hypotheses in a target vocabulary. We stud…

Cited by 0SourceScholar
2021

Mixture of Informed Experts for Multilingual Speech Recognition

ICASSP 2021accepted

When trained on related or low-resource languages, multilingual speech recognition models often outperform their monolingual counterparts. However, these models can suffer from loss in performance for high resource or unrelated languages. We investigate the use of a mixture-of-experts approach to as…

Cited by 0SourceScholar
2020

Generating Diverse and Natural Text-to-Speech Samples Using a Quantized Fine-Grained VAE and Autoregressive Prosody Prior

ICASSP 2020accepted

Recent neural text-to-speech (TTS) models with fine-grained latent features enable precise control of the prosody of synthesized speech. Such models typically incorporate a fine-grained variational autoencoder (VAE) structure, extracting latent features at each input token (e.g., phonemes). However,…

Cited by 0SourceScholar
2020

Improving Speech Recognition Using Consistent Predictions on Synthesized Speech

ICASSP 2020accepted

Speech synthesis has advanced to the point of being close to indistinguishable from human speech. However, efforts to train speech recognition systems on synthesized utterances have not been able to show that synthesized data can be effectively used to augment or replace human speech. In this work,…

Cited by 0SourceScholar
2020

Language-Agnostic Multilingual Modeling

ICASSP 2020accepted

Multilingual Automated Speech Recognition (ASR) systems allow for the joint training of data-rich and data-scarce languages in a single model. This enables data and parameter sharing across languages, which is especially beneficial for the data-scarce languages. However, most state-of-the-art multil…

Cited by 0SourceScholar
2020

Neural Oracle Search on N-BEST Hypotheses

ICASSP 2020accepted

In this paper, we propose a neural search algorithm to select the most likely hypothesis using a sequence of acoustic representations and multiple hypotheses as input. The algorithm provides a sequence level score for each audio-hypothesis pair that is obtained by integrating information from multip…

Cited by 0SourceScholar
2019

Comparison of Data Augmentation and Adaptation Strategies for Code-switched Automatic Speech Recognition

ICASSP 2019accepted

Code-switching occurs when the speaker alternates between two or more languages or dialects. It is a pervasive phenomenon in most Indic spoken languages. Code-switching poses a challenge in language modeling as it complicates the orthographic realization of text, and generally, there is a shortage o…

Cited by 0SourceScholar
2018

Building Competitive Direct Acoustics-to-Word Models for English Conversational Speech Recognition

ICASSP 2018accepted

Direct acoustics-to-word (A2W) models in the end-to-end paradigm have received increasing attention compared to conventional subword based automatic speech recognition models using phones, characters, or context-dependent hidden Markov model states. This is because A2W models recognize words from sp…

Cited by 0SourceScholar
2018

Joint Modeling of Accents and Acoustics for Multi-Accent Speech Recognition

ICASSP 2018accepted

The performance of automatic speech recognition systems degrades with increasing mismatch between the training and testing scenarios. Differences in speaker accents are a significant source of such mismatch. The traditional approach to deal with multiple accents involves pooling data from several ac…

Cited by 0SourceScholar
2018

Measuring the Effect of Linguistic Resources on Prosody Modeling for Speech Synthesis

ICASSP 2018accepted

The generation of natural and expressive prosodic contours is an important component of a text-to-speech (TTS) system which, in most classical architectures, relies on the existence of a text-analysis processor that can extract prosody-predictive features and pass them to a statistical learning mode…

Cited by 0SourceScholar
2017

Effective joint training of denoising feature space transforms and Neural Network based acoustic models

ICASSP 2017accepted

Neural Network (NN) based acoustic frontends, such as denoising autoencoders, are actively being investigated to improve the robustness of NN based acoustic models to various noise conditions. In recent work the joint training of such frontends with backend NNs has been shown to significantly improv…

Cited by 0SourceScholar
2017

End-to-end ASR-free keyword search from speech

ICASSP 2017accepted

End-to-end (E2E) systems have achieved competitive results compared to conventional hybrid hidden Markov model (HMM)-deep neural network based automatic speech recognition (ASR) systems. Such E2E systems are attractive due to the lack of dependence on alignments between input acoustic and output gra…

Cited by 0SourceScholar
2017

End-to-end speech recognition and keyword search on low-resource languages

ICASSP 2017accepted

In recent years, so-called, “end-to-end” speech recognition systems have emerged as viable alternatives to traditional ASR frameworks. Keyword search, localizing an orthographic query in a speech corpus, is typically performed by using automatic speech recognition (ASR) to generate an index. Previou…

Cited by 0SourceScholar
2017

Harmonic feature fusion for robust neural network-based acoustic modeling

ICASSP 2017accepted

Acoustic modeling with deep learning has drastically improved the performance of automatic speech recognition (ASR) where the main stream of the acoustic feature is still log-Mel filtered one. While the log-Mel filtered features lose harmonic-structure information, they still include useful informat…

Cited by 0SourceScholar
2017

Knowledge distillation across ensembles of multilingual models for low-resource languages

ICASSP 2017accepted

This paper investigates the effectiveness of knowledge distillation in the context of multilingual models. We show that with knowledge distillation, Long Short-Term Memory(LSTM) models can be used to train standard feed-forward Deep Neural Network (DNN) models for a variety of low-resource languages…

Cited by 0SourceScholar
2017

Network architectures for multilingual speech representation learning

ICASSP 2017accepted

Multilingual (ML) representations play a key role in building speech recognition systems for low resource languages. The IARPA sponsored BABEL program focuses on building speech recognition (ASR) and keyword search (KWS) systems in over 24 languages with limited training data. The most common mechan…

Cited by 0SourceScholar
2017

Training variance and performance evaluation of neural networks in speech

ICASSP 2017accepted

In this work we study variance in the results of neural network training on a wide variety of configurations in automatic speech recognition. Although this variance itself is well known, this is, to the best of our knowledge, the first paper that performs an extensive empirical study on its effects…

Cited by 0SourceScholar
2017

Voice-transformation-based data augmentation for prosodic classification

ICASSP 2017accepted

In this work we explore data-augmentation techniques for the task of improving the performance of a supervised recurrent-neural-network classifier tasked with predicting prosodic-boundary and pitch-accent labels. The technique is based on applying voice transformations to the training data that modi…

Cited by 0SourceScholar
2016

Efficient one-vs-one kernel ridge regression for speech recognition

ICASSP 2016accepted

Recent evidences suggest that the performance of kernel methods may match that of deep neural networks (DNNs), which have been the state-of-the-art approach for speech recognition. In this work, we present an improvement of the kernel ridge regression studied in Huang et al., ICASSP 2014, and show t…

Cited by 0SourceScholar
2016

Semantic word embedding neural network language models for automatic speech recognition

ICASSP 2016accepted

Semantic word embeddings have become increasingly important in natural language processing tasks over the last few years. This popularity is due to their ability to easily capture rich semantic information through a distributed representation and the availability of fast and scalable algorithms for…

Cited by 0SourceScholar
2016

Using continuous lexical embeddings to improve symbolic-prosody prediction in a text-to-speech front-end

ICASSP 2016accepted

The prediction of symbolic prosodic categories from text is an important, but challenging, natural-language processing task given the various ways in which an input can be realized, and the fact that knowledge about what features determine this realization is incomplete or inaccessible to the model.…

Cited by 0SourceScholar
2015

Bidirectional recurrent neural network language models for automatic speech recognition

ICASSP 2015accepted

Recurrent neural network language models have enjoyed great success in speech recognition, partially due to their ability to model longer-distance context than word n-gram models. In recurrent neural networks (RNNs), contextual information from past inputs is modeled with the help of recurrent conne…

Cited by 0SourceScholar
2015

Unnormalized exponential and neural network language models

ICASSP 2015accepted

Model M, an exponential class-based language model, and neural network language models (NNLM's) have outperformed word n-gram language models over a wide range of tasks. However, these gains come at the cost of vastly increased computation when calculating word probabilities. For both models, the bu…

Cited by 0SourceScholar