Thanos: Energy-Efficient Keyword Spotting Processor with Hybrid Time-Feature-Frequency-Domain Zero-Skipping

In recent years, the keyword spotting algorithm has gained significant attention for applications such as personalized virtual assistants. However, the keyword spotting system must be always turned on to listen to the input voice for the recognition, which worsens the battery constraint problem in the edge devices. In this paper, we first analyze the sparsities in the keyword spotting computation. Based on the characteristic, we introduce the keyword spotting processor called Thanos to enable the zero-skipping scheme in the multiple keyword spotting domains to mitigate the burdensome energy consumption. Experimental results show that our hybrid-domain zero-skipping scheme reduces the latency by 80.3-87.3% and energy consumption by 48.1-79.8% on average, respectively, over the baseline architecture.