Zhihao Du


2025

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OmniFlatten: An End-to-end GPT Model for Seamless Voice Conversation
Qinglin Zhang | Luyao Cheng | Chong Deng | Qian Chen | Wen Wang | Siqi Zheng | Jiaqing Liu | Hai Yu | Chao-Hong Tan | Zhihao Du | ShiLiang Zhang
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)

Full-duplex spoken dialogue systems significantly surpass traditional turn-based dialogue systems, as they allow simultaneous bidirectional communication, closely mirroring human-human interactions. However, achieving low latency and natural interactions in full-duplex dialogue systems remains a significant challenge, especially considering human conversation dynamics such as interruptions, backchannels, and overlapping speech. In this paper, we introduce a novel End-to-End GPT-based model OmniFlatten for full-duplex conversation, capable of effectively modeling the complex behaviors inherent to natural conversations with low latency. To achieve full-duplex conversation capabilities, we propose a multi-stage post-training scheme that progressively adapts a text large language model (LLM) backbone into a speech-text dialogue LLM, capable of generating text and speech in real time, without modifying the architecture of the backbone LLM. The training process comprises three stages: modality alignment, half-duplex dialogue learning, and full-duplex dialogue learning. In all training stages, we standardize the data using a flattening operation, which enables unifying the training methods and the GPT backbone across different modalities and tasks. Our approach offers a simple modeling technique and a promising research direction for developing efficient and natural end-to-end full-duplex spoken dialogue systems.

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UniSpeaker: A Unified Approach for Multimodality-driven Speaker Generation
Zhengyan Sheng | Zhihao Du | Heng Lu | ShiLiang Zhang | Zhen-Hua Ling
Findings of the Association for Computational Linguistics: EMNLP 2025

While recent advances in reference-based speaker cloning have significantly improved the authenticity of synthetic speech, speaker generation driven by multimodal cues such as visual appearance, textual descriptions, and other biometric signals remains in its early stages. To pioneer truly multimodal-controllable speaker generation, we propose UniSpeaker, the first framework supporting unified voice synthesis from arbitrary modality combinations. Specifically, self-distillation is firstly applied to a large-scale speech generation model for speaker disentanglement. To overcome data sparsity and one-to-many mapping challenges, a novel KV-Former based unified voice aggregator is introduced, where multiple modalities are projected into a shared latent space through soft contrastive learning to ensure accurate alignment with user-specified vocal characteristics. Additionally, to advance the field, the first Multimodal Voice Control (MVC) benchmark is established to evaluate voice suitability, diversity, and quality. When tested across five MVC tasks, UniSpeaker is shown to surpass existing modality-specific models. Speech samples and the MVC benchmark are available at https://UniSpeaker.github.io.

2022

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Speaker Overlap-aware Neural Diarization for Multi-party Meeting Analysis
Zhihao Du | ShiLiang Zhang | Siqi Zheng | Zhi-Jie Yan
Proceedings of the 2022 Conference on Empirical Methods in Natural Language Processing

Recently, hybrid systems of clustering and neural diarization models have been successfully applied in multi-party meeting analysis. However, current models always treat overlapped speaker diarization as a multi-label classification problem, where speaker dependency and overlaps are not well considered. To overcome the disadvantages, we reformulate overlapped speaker diarization task as a single-label prediction problem via the proposed power set encoding (PSE). Through this formulation, speaker dependency and overlaps can be explicitly modeled. To fully leverage this formulation, we further propose the speaker overlap-aware neural diarization (SOND) model, which consists of a context-independent (CI) scorer to model global speaker discriminability, a context-dependent scorer (CD) to model local discriminability, and a speaker combining network (SCN) to combine and reassign speaker activities. Experimental results show that using the proposed formulation can outperform the state-of-the-art methods based on target speaker voice activity detection, and the performance can be further improved with SOND, resulting in a 6.30% relative diarization error reduction.