I saw a gadget once where they used a motion sensor to sense when the washer and dryer were done.

I have a baby monitor for my kids (1 way audio because I wanted to limit the privacy risk and I suspect more than that can lead to some bad habits) and it clearly filters for sounds at roughly the frequency of kids voices because you can’t consistently say something over it and hear it on the other side, but my kid can go up to it and dictate a 500 word essay that summarizes down to “there’s a bug on the window” and we’ll hear every breath and word