| Step | Process | Description | |------|---------|-------------| | 1 | | A low-power, always-listening circuit detects a specific phrase (e.g., "Hey Siri," "Alexa"). This is often done on-device for privacy. | | 2 | Voice Activity Detection (VAD) | Separates human speech from background noise to know when a command starts/ends. | | 3 | Feature Extraction | Converts audio into digital signals (MFCCs—Mel-frequency cepstral coefficients). | | 4 | Automatic Speech Recognition (ASR) | Transforms speech to text using deep learning models (e.g., RNNs, Transformers). | | 5 | Natural Language Understanding (NLU) | Parses intent and extracts entities (e.g., "turn on" = intent; "lights" = entity). | | 6 | Command Execution | Triggers an action via API calls, device drivers, or automation rules. |
Unlike continuous speech recognition (dictation), VAC focuses on action-oriented phrases (e.g., "turn on lights," "call Mom," "volume up"). 2. How VAC Works: The Technical Stack VAC systems rely on a multi-layered process, typically executed locally or via cloud: VAC -Voice Activated Commands-
1. Definition & Core Concept Voice Activated Commands (VAC) refer to a technology that enables a device or system to recognize and execute specific spoken instructions without requiring physical input (like a keyboard, mouse, or touchscreen). The "activated" aspect implies a trigger mechanism—often a wake word—followed by a command. | | 3 | Feature Extraction | Converts
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