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When interacting with smart devices such as mobile- phones or wearables, the user typically invokes a virtual assistant (VA) by saying a keyword or by pressing a but- ton on the device. However, in many cases, the VA can accidentally be invoked by the keyword-like speech or ac- cidental button press, which may have implications on user experience and privacy. To this end, we propose an acous- tic false-trigger-mitigation (FTM) approach for on-device device-directed speech detection that simultaneously handles the voice-trigger and touch-based invocation. To facilitate the model deployment on-device, we introduce a new streaming decision layer, derived using the notion of temporal convo- lutional networks (TCN) [1], known for their computational efficiency. To the best of our knowledge, this is the first ap- proach that can detect device-directed speech from more than one invocation type in a streaming fashion. We compare this approach with streaming alternatives based on vanilla Average layer, and canonical LSTMs, and show: (i) that all the models show only a small degradation in accuracy compared with the invocation-specific models, and (ii) that the newly introduced streaming TCN consistently performs better or comparable with the alternatives, while mitigating device- undirected speech faster in time, and with (relative) reduction in runtime peak-memory over the LSTM-based approach of 33% vs. 7%, when compared to a non-streaming counterpart.

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