Google Assistant devices listen for a wake word so they can respond quickly. This means the microphone is on, but they are designed to process the wake word locally. After the wake word is detected, the device sends audio to Google servers to answer your request. You can review and delete voice history in your account settings.
Most devices have a physical mute switch that stops the microphones. If you use the assistant on a phone, you can turn off the hotword feature or limit microphone access. Privacy controls are worth reviewing to match your comfort level. If privacy is critical, choose devices that support on device processing and use the mute switch when not needed during downtime at home.
