Kai-Wei Chang
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2026
MP-Bench: Evaluating Voice Agents as a Multiparty Conversation Participant
Yi-Jen Shih | Shih-Yun Shan Kuan | Guan-Ting Lin | Kai-Wei Chang | Siddhant Arora | Shu-wen Yang | Abdelrahman Mohamed | Shinji Watanabe | Hung-yi Lee | David Harwath
Findings of the Association for Computational Linguistics: EMNLP 2026
Yi-Jen Shih | Shih-Yun Shan Kuan | Guan-Ting Lin | Kai-Wei Chang | Siddhant Arora | Shu-wen Yang | Abdelrahman Mohamed | Shinji Watanabe | Hung-yi Lee | David Harwath
Findings of the Association for Computational Linguistics: EMNLP 2026
Conversational voice agents have advanced significantly, offering increasingly natural human-machine interactions through both cascaded and end-to-end architectures. However, while recent benchmarks extensively evaluate dyadic interactions and passive audio comprehension, they largely overlook a prevalent real-world scenario: multi-party conversations. Evaluating agents in these settings is fundamentally more challenging than in dyadic interactions due to the exponentially greater conversational complexity. For voice agents to integrate seamlessly into human group dynamics, they must not only generate contextually appropriate responses but also demonstrate a nuanced understanding of open turn-taking. To address this gap, we introduce Multiparty Bench (MP-Bench), the first benchmark specifically designed to objectively evaluate conversational speech systems as active participants within multi-party contexts. MP-Bench assesses agent behavior along two primary dimensions: turn-taking awareness and response appropriateness. Additionally, we incorporate comprehension-based question-answering tasks as a complementary evaluation. By benchmarking 12 voice agents, we find that real-time voice agents stay at or below 22% on multiparty comprehension and remain near chance on multiparty turn-taking, exposing an open challenge for real-time voice agents under multiparty scenario.
On the Fallacy of Global Token Perplexity in Spoken Language Model Evaluation
Chan-Jan Hsu | Liang-Hsuan Tseng | Yi-Cheng Lin | Yen-Chun Kuo | Ju-Chieh Chou | Kai-Wei Chang | Hung-yi Lee | Carlos Busso
Findings of the Association for Computational Linguistics: ACL 2026
Chan-Jan Hsu | Liang-Hsuan Tseng | Yi-Cheng Lin | Yen-Chun Kuo | Ju-Chieh Chou | Kai-Wei Chang | Hung-yi Lee | Carlos Busso
Findings of the Association for Computational Linguistics: ACL 2026
Generative spoken language models pretrained on large-scale raw audio can continue a speech prompt with appropriate content while preserving attributes like speaker and emotion, serving as foundation models for spoken dialogue. In prior literature, these models are often evaluated using “global token perplexity”, which directly applies the text perplexity formulation to speech tokens. However, this practice overlooks fundamental differences between speech and text modalities, possibly leading to an underestimation of the speech characteristics. In this work, we propose a variety of likelihood- and generative-based evaluation methods that serve in place of naive global token perplexity. We demonstrate that the proposed evaluations more faithfully reflect perceived generation quality, as evidenced by stronger correlations with human-rated mean opinion scores (MOS). When assessed under the new metrics, the relative performance landscape of spoken language models is reshaped, revealing a significantly reduced gap between the best-performing model and the human topline. Together, these results suggest that appropriate evaluation is critical for accurately assessing progress in spoken language modeling.
Unsupervised Speech Recognition at the Syllable Level
Liming Wang | Kai-Wei Chang | Kunio Kashino | David Harwath | Mark A. Hasegawa-Johnson | James R. Glass
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Liming Wang | Kai-Wei Chang | Kunio Kashino | David Harwath | Mark A. Hasegawa-Johnson | James R. Glass
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Training speech recognizers with unpaired speech and text – known as unsupervised speech recognition (UASR) – is a crucial step toward extending ASR to low-resource languages in the long-tail distribution and enabling multimodal learning from non-parallel data. However, existing approaches based on phones often rely on costly resources such as grapheme-to-phoneme converters (G2Ps) and struggle to generalize to languages with ambiguous phoneme boundaries due to training instability. In this paper, we address both challenges by introducing a syllable-level UASR framework based on masked language modeling, which avoids the need for G2P and the instability of GAN-based methods. Our approach achieves up to a 40% relative reduction in character error rate (CER) on LibriSpeech and generalizes effectively to low-resource languages that have remained particularly difficult for prior methods. Code will be released upon acceptance.
BILLY: Steering Large Language Models via Merging Persona Vectors for Creative Generation
Tsung-Min Pai | Jui-I Wang | Li-Chun Lu | Shao-Hua Sun | Hung-yi Lee | Kai-Wei Chang
Proceedings of the 19th Conference of the European Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)
Tsung-Min Pai | Jui-I Wang | Li-Chun Lu | Shao-Hua Sun | Hung-yi Lee | Kai-Wei Chang
Proceedings of the 19th Conference of the European Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)
Multi-LLM systems enhance the creativity of large language models by simulating human collective intelligence but suffer from significant drawbacks, such as high computational costs and inference latency. To address these limitations, we propose BILLY (BlendIng persona vectors for Large Language model creativitY), a training-free framework that captures the benefits of multi-LLM collaboration, i.e. inducing diverse perspectives and specialized expertise, within a single model. BILLY operates by extracting and blending multiple distinct persona vectors directly in the model’s activation space. We steer the model’s generation process with this merged vector while inference, enabling multi-perspective output without explicit multi-LLM communication. Our experiments across creativity-oriented benchmarks demonstrate that BILLY surpasses single model prompting and traditional multi-LLM approaches, while substantially reducing inference time and computational costs. Our analyses further reveal that distinct persona vectors can be blended to achieve both effective control over complementary aspects of generation and greater interpretability.
Full-Duplex-Bench-v2: A Multi-Turn Evaluation Framework for Duplex Dialogue Systems with an Automated Examiner
Guan-Ting Lin | Shih-Yun Shan Kuan | Jiatong Shi | Kai-Wei Chang | Siddhant Arora | Shinji Watanabe | Hung-yi Lee
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 2: Short Papers)
Guan-Ting Lin | Shih-Yun Shan Kuan | Jiatong Shi | Kai-Wei Chang | Siddhant Arora | Shinji Watanabe | Hung-yi Lee
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 2: Short Papers)
While full-duplex speech agents enable natural, low-latency interaction by speaking and listening simultaneously, their consistency and task performance in multi-turn settings remain underexplored. We introduce Full-Duplex-Bench-v2 (FDB-v2), a streaming framework that integrates with an automated examiner that enforces staged goals under two pacing setups (Fast vs. Slow). FDB-v2 covers four task families—Daily, Correction, Entity Tracking, and Safety—and reports turn-taking fluency, multi-turn instruction following, and task-specific competence. The framework is extensible, supporting both commercial APIs and open-source models. When we test full-duplex systems with FDB-v2, they often get confused when people talk at the same time, struggle to handle corrections smoothly, and sometimes lose track of who or what is being talked about. Through an open-source, standardized streaming protocol and a task set, FDB-v2 makes it easy to extend to new task families, allowing the community to tailor and accelerate evaluation of multi-turn full-duplex systems.