Apple engineers and scientists from Carnegie Mellon University taught HomePod to recognize various characteristic sounds. See the video.
The system was called Listen Learner. As you can see in the video below, when HomePod hears a sound like a knock on the door or the sound of the microwave ending will ask a simple question. What is that sound? Just answer, for example. it’s a microwave oven for HomePod to remember the sound.
What do you need it for? In the video above you can see that when HomePod hears the sound recorded earlier, information is sent to our iPhone, for example about the end of the microwave oven or about someone knocking on our door.