> Furthermore, the listening approach can be expanded to listen for other things besides smoke detectors just be changing software. You could add listening for your doorbell, or your telephone, or your dog barking, or glass breaking.

Or a whistling gas kettle, which is an actual use case for me.

Generally, I very like the approach of listening and trying to recognize sounds. It's much more flexible than trying to put a brain in every other thing you have at home.