“One prevalent use of ML on microcontrollers (TinyML) includes wake word detection, which is also known as keyword spotting. For example, if you say “Alexa” or “Hey Siri,” your phone or nearby smart speaker may come to life, waiting for further instructions. The smart speaker uses two types of machine learning. The first kind is TinyML, where inference is performed locally in the speaker’s microcontroller to listen for that wake word. Once the speaker hears the wake word, it begins streaming the subsequent audio to an internet-connected server, which performs a much more complex machine learning process known as natural language processing (NLP) to figure out what you’re asking.”
https://makezine.com/2022/05/16/level-up-your-ai-skillset-and-dive-iinto-the-deep-eend-of-tinyml/