Toward fast meeting transcription: NAIST system for CHiME-8 NOTSOFAR-1 task and its analysis

Abstract

This paper reports on the NAIST system submitted to the CHIME-8 challenge’s NOTSOFAR-1 (Natural Office Talkers in Settings of Far-field Audio Recordings) task, including results and analyses from several additional experiments. While fast processing is crucial for real-world applications, the CHIME-7 challenge focused solely on reducing error rate, neglecting the practical aspects of system performance such as inference speed. Therefore, this research aims to develop a practical system by improving recognition accuracy while simultaneously reducing inference speed. To address this challenge, we propose enhancing the baseline module architecture by modifying both the CSS and ASR modules. Specifically, the ASR module was built based on a WavLM large feature extractor and a Zipformer transducer. Furthermore, we employed reverberation removal using block-wise weighted prediction error (WPE) as preprocessing for the speech separation module. The proposed system achieved a relative reduction in tcpWER of 11.6% for single-channel tracks and 18.7% for multi-channel tracks compared to the baseline system. Moreover, the proposed system operates up to six times faster than the baseline system while achieving superior tcpWER results. We also report on the observed changes in system performance due to variations in the amount of training data for the ASR model, as well the impact of the maximum word-length setting in the transducer-based ASR module on the subsequent diarization system, based on findings from our system development.