  In a speech recognition system, voice activity detection (VAD) is a crucial
frontend module. Addressing the issues of poor noise robustness in traditional
binary VAD systems based on DFSMN, the paper further proposes semantic VAD
based on multi-task learning with improved models for real-time and offline
systems, to meet specific application requirements. Evaluations on internal
datasets show that, compared to the real-time VAD system based on DFSMN, the
real-time semantic VAD system based on RWKV achieves relative decreases in CER
of 7.0\%, DCF of 26.1\% and relative improvement in NRR of 19.2\%. Similarly,
when compared to the offline VAD system based on DFSMN, the offline VAD system
based on SAN-M demonstrates relative decreases in CER of 4.4\%, DCF of 18.6\%
and relative improvement in NRR of 3.5\%.
