A smart microphone integrates a traditional microphone with ultra-low-power digital signal processing technology for extracting command information from a human voice. When an application only needs a small set of commands, the DSP capability within the smart microphone can do all the computing locally without waking up the main system or connecting to a server. This capability is the key to interfacing with the human voice interface in smart appliances, TVs, robots and other digital assistants for both consumer and industrial applications.
Source: Texas Instruments
How do smart microphones actually work? Well, a microphone converts a sound wave into an electric signal. The electric signal is amplified and low pass-filtered by the analog amplifier for proper sampling by an analog-to-digital converter. The acoustic feature extraction block pulls the acoustic feature vectors from the microphone data and presents the results to the command decoder block. In order to recognize short commands, the command decoder block checks the accumulated acoustic feature vector (maybe for 1second) against information from acoustic models and the command list table to see if there is a valid command. If a valid command is found, the smart microphone then sends it to the main system.
To learn more about smart microphone design including the unique acoustic feature extraction, click here.