How do microphone sensors fit into a smart home?

A quick search for “sensors in the smart home” can easily identify dozens of sensors – primarily for sensing physical properties. The results could be one of many specific sensing technologies or specific products. For example, one search showed:

Fire/CO detection
Leak/moisture detection
Window & door open and close
Video doorbell
Smart thermostat
Motion sensors

Multi-sensor products combines several sensors (and sensing technologies) into one device, for example: motion, temperature, light, humidity, vibration and ultraviolet (UV) sensing.

However, using a voice assistant like Alexa, Siri or Google Assistant definitely involves a microphone. Voice assistants can activate and control specific functions in connected smart home devices. In a remote control, voice assistance allows the user to quickly find a desired station or content on a smart TV. Microphones are also necessary for sound detection in burglar detection systems, baby and even pet monitoring. For these security applications, standalone voice assistant use microphones to alert users to the sound of alarms and broken glass. Baby monitors have both video (camera) and audio (microphone) inputs to provide safety.

Either digital or analog microelectromechanical systems (MEMS) microphones are used to provide the voice and/or sound detection in these types of sensing applications. For these end products, Infineon Technologies’ XENSIV MEMS microphones were designed to add audio input to an ever-expanding number of applications.

For example, Infineon’s IM69D130 is designed for applications where low self-noise (high signal to noise ratio (SNR)), wide dynamic range, low distortions and a high acoustic overload point are required. Using the company’s Dual Backplate MEMS technology, the microphone can deliver 105 dB dynamic range and high output linearity up to 130 dBSPL. The recently released analog IM73A135 microphone pushes the level of audio performance even further. It offers an SNR of 73 dB(A) and sensitivity tolerances of ± 1 dB.