https://www.cnet.com/news/use-google-home-as-your-family-dinner-bell-with-broadcast/

Google Assistant's newest feature wants to help you save your voice when you make family announcements. Instead of shouting up the stairs when it's time for a meal or a meeting, just issue a command to Google's digital helper and it can broadcast your announcement for you.

First announced in October, Google's Broadcast feature starts rolling out Monday. Say, "OK Google, broadcast 'it's time for school'" to any device equipped with Google Assistant, and that message will play on any other Assistant-enabled speakers in your home. Certain messages, such as, "OK Google, broadcast 'it's dinner time'" will even include custom sound effects. The dinner time example will ring a dinner bell.