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Barry-John Theobald

19 accepted papers

2026

DSO: Direct Steering Optimization for Bias Mitigation

CVPR 2026

Generative models are often deployed to make decisions on behalf of users, such as vision-language models (VLMs) identifying which person in a room is a doctor to help visually impaired individuals. Yet, VLM decisions are influenced by the perceived demographic attributes of people in the input, whi

Cited by 0SourceScholar
2026

Normalized Rewards for Preference Optimization

ICML 2026poster

Direct Alignment Algorithms (DAAs) such as DPO have become a common way to post-train and align LLMs with human preferences. However, DAAs have been observed to over-optimize their implicit reward model and decrease the likelihood of preferred responses. This results in a decrease in the total likel…

Cited by 0SourceScholar
2025

Aligning LLMs by Predicting Preferences from User Writing Samples

ICML 2025poster

Accommodating human preferences is essential for creating aligned LLM agents that deliver personalized and effective interactions. Recent work has shown the potential for LLMs acting as writing agents to infer a description of user preferences. Agent alignment then comes from conditioning on the inf…

2025

Bias after Prompting: Persistent Discrimination in Large Language Models

EMNLP 2025

A dangerous assumption that can be made from prior work on the bias transfer hypothesis (BTH) is that biases do not transfer from pre-trained large language models (LLMs) to adapted models. We invalidate this assumption by studying the BTH in causal models under prompt adaptations, as prompting is a

Cited by 0SourcePDFScholar
2025

Exploring Prediction Targets in Masked Pre-Training for Speech Foundation Models

ICASSP 2025accepted

Speech foundation models, such as HuBERT and its variants, are pre-trained on large amounts of unlabeled speech data and then used for a range of downstream tasks. These models use a masked prediction objective, where the model learns to predict information about masked input segments from the unmas…

Cited by 0SourceScholar
2025

Is Your Model Fairly Certain? Uncertainty-Aware Fairness Evaluation for LLMs

ICML 2025poster

The recent rapid adoption of large language models (LLMs) highlights the critical need for benchmarking their fairness. Conventional fairness metrics, which focus on discrete accuracy-based evaluations (i.e., prediction correctness), fail to capture the implicit impact of model uncertainty (e.g., hi…

2025

Proxy-FDA: Proxy-based Feature Distribution Alignment for Fine-tuning Vision Foundation Models without Forgetting

ICML 2025poster

Vision foundation models pre-trained on massive data encode rich representations of real-world concepts, which can be adapted to downstream tasks by fine-tuning. However, fine-tuning foundation models on one task often leads to the issue of *concept forgetting* on other tasks. Recent methods of robu…

Cited by 0SourcePDFScholar
2025

Speaker-IPL: Unsupervised Learning of Speaker Characteristics with i-Vector based Pseudo-Labels

ICASSP 2025accepted

Iterative self-training, or iterative pseudo-labeling (IPL)—using an improved model from the current iteration to provide pseudo-labels for the next iteration—has proven to be a powerful approach to enhance the quality of speaker representations. Recent applications of IPL in unsupervised speaker re…

Cited by 0SourceScholar
2025

Steering into New Embedding Spaces: Analyzing Cross-Lingual Alignment Induced by Model Interventions in Multilingual Language Models

ACL 2025long

Aligned representations across languages is a desired property in multilingual large language models (mLLMs), as alignment can improve performance in cross-lingual tasks. Typically alignment requires fine-tuning a model, which is computationally expensive, and sizable language data, which often may…

Cited by 0SourcePDFScholar
2025

Towards Automatic Assessment of Self-Supervised Speech Models using Rank

ICASSP 2025accepted

This study explores using embedding rank as an unsupervised evaluation metric for general-purpose speech encoders trained via self-supervised learning (SSL). Traditionally, assessing the performance of these encoders is resource-intensive and requires labeled data from the downstream tasks. Inspired…

Cited by 0SourceScholar
2024

Can You Rely on Synthetic Labellers in Preference-Based Reinforcement Learning? It’s Complicated

AAAI 2024technical

Preference-based Reinforcement Learning (PbRL) enables non-experts to train Reinforcement Learning models using preference feedback. However, the effort required to collect preference labels from real humans means that PbRL research primarily relies on synthetic labellers. We validate the most commo…

Cited by 2SourcePDFScholar
2024

Learning Spatially-Aware Language and Audio Embeddings

NeurIPS 2024poster

Humans can picture a sound scene given an imprecise natural language description. For example, it is easy to imagine an acoustic environment given a phrase like "the lion roar came from right behind me!". For a machine to have the same degree of comprehension, the machine must know what a lion is (…

Cited by 1SourcePDFScholar
2024

On the Limited Generalization Capability of the Implicit Reward Model Induced by Direct Preference Optimization

EMNLP 2024finding

Reinforcement Learning from Human Feedback (RLHF) is an effective approach for aligning language models to human preferences. Central to RLHF is learning a reward function for scoring human preferences. Two main approaches for learning a reward model are 1) training an EXplicit Reward Model (EXRM) a…

2023

Naturalistic Head Motion Generation from Speech

ICASSP 2023accepted

Synthesizing natural head motion to accompany speech for an embodied conversational agent is necessary for pro-viding a rich interactive experience. Most prior works assess the quality of generated head motion by comparing them against a single ground-truth using an objective metric. Yet there are m…

Cited by 0SourceScholar
2023

On the Role of LIP Articulation in Visual Speech Perception

ICASSP 2023accepted

Generating realistic lip motion from audio to simulate speech production is critical for driving natural character animation. Previous research has shown that traditional metrics used to optimize and assess models for generating lip motion from speech are not a good indicator of subjective opinion o…

Cited by 0SourceScholar
2023

Sample-Efficient Preference-based Reinforcement Learning with Dynamics Aware Rewards

CoRL 2023poster

Preference-based reinforcement learning (PbRL) aligns a robot behavior with human preferences via a reward function learned from binary feedback over agent behaviors. We show that encoding environment dynamics in the reward function improves the sample efficiency of PbRL by an order of magnitude. In…

Cited by 7SourcecodeScholar
2021

On The Role of Visual Cues in Audiovisual Speech Enhancement

ICASSP 2021accepted

We present an introspection of an audiovisual speech enhancement model. In particular, we focus on interpreting how a neural audiovisual speech enhancement model uses visual cues to improve the quality of the target speech signal. We show that visual cues provide not only high-level information abou…

Cited by 0SourceScholar
2015

A mouth full of words: Visually consistent acoustic redubbing

ICASSP 2015accepted

This paper introduces a method for automatic redubbing of video that exploits the many-to-many mapping of phoneme sequences to lip movements modelled as dynamic visemes (Taylor et al., 2012). For a given utterance, the corresponding dynamic viseme sequence is sampled to construct a graph of possible…

Cited by 0SourceScholar