Three-stage modular speaker diarization collaborating with front-end techniques in the CHiME-8 NOTSOFAR-1 challenge

Shutong Niu, RuoYu Wang, Jun Du, Gaobin Yang, Tian Gao, Jia Pan, Qingfeng Liu

Abstract: We propose a modular speaker diarization framework that collaborates with front-end techniques in a three-stage process, designed for the challenging CHiME-8 NOTSOFAR-1 acoustic environment. The framework leverages the strengths of deep learning based speech separation systems and traditional speech signal processing techniques to provide more accurate initializations for the Neural Speaker Diarization (NSD) system at each stage, thereby enhancing the performance of a single-channel NSD system. Firstly, speaker overlap detection and Continuous Speech Separation (CSS) are applied to the multichannel speech to obtain clearer single-speaker speech segments for the Clustering-based Speaker Diarization (CSD), followed by the first NSD decoding. Next, the binary speaker masks from the first decoding are used to initialize a complex Angular Center Gaussian Mixture Model (cACGMM) to estimate speaker masks on the multi-channel speech. Using Mask-to-VAD post-processing techniques, we achieve per-speaker speech activity with reduced speaker error (SpkErr), followed by a second NSD decoding. Finally, the second decoding results are used to Guide Source Separation (GSS) to produce per-speaker speech segments. Short utterances containing one word or fewer are filtered, and the remaining speech segments are re-clustered for the final NSD decoding. We present evaluation results progressively explored from the CHiME-8 NOTSOFAR-1 challenge, demonstrating the effectiveness of our modular diarization system and its contribution to improving speech recognition performance.